JP2009253785A - Multiband high-frequency power amplifier - Google Patents

Abstract

[PROBLEMS] To eliminate unnecessary signal frequencies in a frequency band lower than the fundamental wave with a simple configuration using a bypass capacitor, suppress noise sources and unnecessary spurious, and supply power with a simple circuit of an output matching circuit and a bypass capacitor. Collect lines and reduce power supply terminals.
From a fundamental wave, a low frequency rejection circuit 7 is connected between a power supply line 5 and a power terminal 6 of a high frequency power amplifier, and an inductor (or microwave transmission line) 72 is connected in series to a plurality of bypass capacitors 71. Remove unwanted signals at lower frequencies. It eliminates and suppresses unnecessary signal frequencies such as reception band noise and oscillation spurious in a frequency band lower than the fundamental frequency, thereby improving wireless communication quality. Further, the power source terminals of a plurality of high frequency power amplifiers are shared by the low frequency elimination circuit 7 to reduce the power source terminals. Thereby, size reduction, weight reduction, and cost reduction of a circuit part can be achieved.
[Selection] Figure 1

Description

  The present invention relates to a multiband high-frequency power amplifier used in the field of wireless communication, and in particular, in a high-frequency power amplification transistor included in a plurality of high-frequency power amplifiers, one power supply line for each of the plurality of high-frequency power amplification transistors is provided. The noise and spurious generated in the low-frequency band of the high-frequency power amplifier are removed by the low-frequency rejection circuit consisting of the power supply common line and multiple bypass capacitors connected in series with the inductive reactance component. The present invention relates to a technology that makes it possible to reduce the number of power supply terminals for supplying power to an amplifier.

  In recent years, there has been a growing demand for mobile phone terminals such as multi-mode to support international roaming that can be used overseas and multi-band to ensure more stable communication quality while expanding communication capacity. It is coming. In multi-mode and multi-band, the third generation (3G) system such as CDMA (Code Division Multiple Access) system and UMTS (Universal Mobile Telecommunications System) system uses 800 MHz band, 1.7 GHz band, and 2 GHz band in Japan. Overseas, the 850 MHz band, 900 MHz band, 1.8 GHz band, and 1.9 GHz band of the GSM (Global System for Mobile Communications) system that is widely used overseas are used in each region.

  In order to cope with such multi-mode and multi-band, a mobile phone terminal needs to be equipped with a plurality of high-frequency power amplifiers, which is a problem in miniaturization of the RF circuit section.

  In addition, these high-frequency reception bands, including the addition of functions such as digital TV to mobile phone terminals: 470 to 770 MHz and GPS (Global Positioning System): 1.57 GHz, and mobile phone use frequency bands associated with multimode / multibanding. Noise and unwanted spurious drops in the signal cause degradation in reception performance, and therefore a high-frequency power amplifier that suppresses noise and unwanted spurious levels over a wider frequency range is required.

  Therefore, Patent Document 1 proposes a technique for removing noise in a wide band by connecting two bypass capacitors in parallel to the power supply line. Further, Patent Document 2 proposes a technique for removing noise in a wide range by a band rejection filter circuit using a choke coil (coil filter) in a power supply line.

  In Patent Document 1, by connecting two bypass capacitors having different self-resonance frequencies to the power supply terminal in parallel, the AC grounding effect obtained in a wider range than when using the self-resonance frequency of one bypass capacitor, This technology removes noise over a wide band.

  In Patent Document 2, a choke coil is connected in series to a power supply line, and a capacitor is grounded at the end of the choke coil. It is a technology to remove.

  FIG. 10A shows a circuit example of a T-type filter disclosed in Patent Document 2, and FIG. 10B shows a circuit of a π-type filter. In the T-type filter shown in FIG. 10A, inductors L1 and L2 having different inductor values are connected in series to the power supply line, and a capacitor C1 is connected between the inductors and grounded. Considering high-density mounting with less electromagnetic coupling between inductors by using a choke coil (coil filter) for at least one of L2. The π-type filter circuit shown in FIG. 10B is constituted by a choke coil (coil filter) L3 and capacitors C2 and C3, and meets desired characteristics with a combination of T-type and π-type according to the application. I advocate.

Furthermore, in order to reduce the size of the multiband, in Patent Document 3, in a plurality of high-frequency power amplifiers, a part of the components in each power supply circuit is shared with a plurality of amplifying elements, so that a power supply terminal is provided. It proposes a miniaturization technology by reducing the number of power terminals by making it common.
JP 2006-080806 A JP 2003-198305 A Japanese Patent No. 3899826

  However, each of these high-frequency power amplifiers has the following problems.

  In Patent Document 1, as an example, two bypass capacitors having different self-resonance frequencies are grounded to each power supply terminal of the voltage controlled oscillator, and an AC grounding effect is obtained that removes noise and the like in a frequency range of 0.5 GHz to 4 GHz. ing.

  However, as shown in the circuit configuration of a general high-frequency power amplifier shown in FIG. 11, the power supply line 5 connected to the output terminal 4 of the high-frequency power amplification transistor 3 is connected to the output terminal 4 of the high-frequency power amplification transistor 3. The electrical length of the power supply line 5 is set to the λ / 4 length of the fundamental wave in order to design the impedance as viewed from the power source to be sufficiently large, preferably open. When the λ / 4 length cannot be secured, the parallel capacitor used in the output matching circuit 8 is adjusted so that the impedance viewed from the power supply side from the output terminal 4 of the high frequency power amplification transistor 3 can be seen as open.

  A graph A (solid line) in FIG. 12 shows pass characteristics of only a circuit in which two types of bypass capacitors 7A and 7B having different capacities are connected to the power supply terminal 6. In the example, a capacity of 100,000 pF having a self-resonance frequency of about 30 MHz and a capacity of 220 pF having a self-resonance frequency of about 550 MHz are used for the bypass capacitor 7A.

  A graph B (broken line) in FIG. 12 shows the circuit from the high frequency power amplification transistor 3 to the output matching circuit 8 when the power supply line 5 set to the λ / 4 length of the fundamental wave is added to the circuit of the graph A in FIG. The pass characteristic S21 (dB) is shown. In this circuit, the fundamental wave is 800 MHz.

  In graph B of FIG. 12, the self-resonant frequency of 220 pF moves to the lower frequency side due to the power supply line length set to the λ / 4 length of the fundamental wave, and a notch due to resonance cannot be confirmed near 400 MHz. This is because the influence of the power supply line length set to the λ / 4 length of the fundamental wave that shows the fundamental impedance open is visible even in the frequency band near the fundamental wave, and the self-resonance of the bypass capacitor installed at the power supply terminal The AC grounding effect using only the frequency becomes weaker as the band is closer to the fundamental frequency, and the effect does not appear. In particular, it is difficult to effectively remove noise and spurious generated from the vicinity of 1/5 of the fundamental frequency to the fundamental frequency.

  In Patent Literature 2, a T-type filter using a choke coil (coil filter) or a broadband blocking filter such as a π-type filter is used for the inductor L shown in FIGS. 10A and 10B connected in series to the power supply line. Although noise is removed in a wide band, the coil connected in series with the power supply line is required to have a low resistance in order to avoid a loss due to a voltage drop that affects the efficiency of the high-frequency power amplifier. For this reason, the choke coil (coil filter) generally employs a winding structure, and the wideband blocking filter using such an expensive choke coil (coil filter) that is difficult to reduce in size is used as a multiband high-frequency filter. There are limitations in terms of size and price to use for each power supply terminal of the power amplifier.

  In Patent Document 3, in a plurality of high-frequency power amplifiers, the fundamental impedance on the power source side viewed from the output terminal of one high-frequency power amplifier transistor shares the power source terminal in addition to its own power supply line and bypass capacitor. By combining and designing all other impedances of other high-frequency power amplification transistors and power supply lines connected to their output terminals, bypass capacitors and output matching circuits, it is larger than the real part of the impedance of its own output matching circuit It is set to be. In this method, since the fundamental impedance on the power source side seen from the output terminal of one high frequency power amplification transistor depends on various parameters including the counterpart transistor, output matching circuit, power supply line, and bypass capacitor, In addition to increasing the difficulty of development design, production problems such as deterioration of characteristic variations occur.

  The present invention is directed to solving the problems of the prior art, and by removing unnecessary signal frequencies in a frequency band lower than the fundamental frequency by a simple circuit configuration using a bypass capacitor, It is possible to obtain effects such as suppression of noise sources from the inside and unwanted spurious generated inside, and the power supply of the multiband high-frequency power amplifier by a simple circuit configuration using the output matching circuit of each transistor and a bypass capacitor The supply lines are combined into one to enable miniaturization by reducing the number of power supply terminals.

To achieve the above object, the multi-band high-frequency power amplifier of the present invention comprises N high-frequency power amplifiers that amplify different high-frequency signals,
Further, each high frequency power amplifier includes a plurality of (K stage) high frequency power amplifying transistors and an input matching circuit on the input side for fundamental wave impedance matching between the high frequency power amplifying transistors or external devices existing before and after this. And an output matching circuit on the output side,
Furthermore, a power supply line that supplies a power supply voltage between the output terminal and the power supply terminal of the high-frequency power amplification transistor, and a power supply so that the impedance viewed from the high-frequency power amplification transistor output terminal of the power supply line is almost open Adjusted by the electrical length of the supply line or output matching circuit, and connected in series with an inductor (or microwave transmission line) with the function of removing unnecessary signal frequencies in the frequency band lower than the fundamental wave on the power supply terminal side of the power supply line A low-frequency rejection circuit including M bypass capacitors,
Each power supply line of the N high frequency power amplifiers is connected corresponding to each of the M bypass capacitors included in the low frequency elimination circuit, and the N high frequency power amplifiers are connected to one low frequency elimination circuit and 1 Share two power terminals.

  According to the above configuration, unnecessary signal frequencies in a frequency band lower than the fundamental frequency are removed by a simple circuit configuration using a bypass capacitor, and noise sources from the outside and inside and unwanted spurious generated internally are removed. In addition, the power supply terminals of the multiband high-frequency power amplifier can be combined into one with a simple configuration of the output matching circuit of each transistor and the bypass capacitor, and the power supply terminals can be reduced.

  According to the present invention, each high-frequency power amplifier of the multiband high-frequency power amplifier is composed of a plurality of stages of high-frequency power amplification transistors, and all of the power supply lines of the K-th high-frequency power amplification transistors in each high-frequency power amplifier. The low-frequency rejection circuit connected to the low-frequency rejection circuit removes the low frequency band below the lowest frequency among the fundamental frequencies amplified by the high-frequency power amplifiers, so that Each high frequency power amplifier is more stable and improves noise performance by eliminating frequency noise, suppressing reception band noise close to the fundamental frequency generated by itself, and suppressing unnecessary spurious such as 1/2 oscillation generated by itself. In addition, all power supply lines of the K-stage high frequency power amplification transistors in each high frequency power amplifier are bundled. By connecting to a low-frequency rejection circuit, power supply terminals can be reduced, ensuring stable communication quality, and reducing the size, weight, and cost of the RF circuit, which are issues for multiband high-frequency power amplifiers There is an effect that can be solved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking as an example a multiband high-frequency power amplifier that amplifies frequencies from the 800 MHz band to the 2 GHz band used in domestic mobile phones as a fundamental frequency.

(First embodiment)
FIG. 1 is a diagram showing a low frequency elimination circuit installed at the power supply terminal of the high frequency power amplifier according to the first embodiment of the present invention. Also, components having the same functions corresponding to the components described in FIG. 11 showing the conventional example are given the same reference numerals, and the same applies to the following drawings.

  As shown in FIG. 1, a basic configuration of a high-frequency power amplifier 10 having a low-frequency elimination circuit 7 is a high-frequency power amplifier 10 composed of a single-stage high-frequency power amplifier transistor 3. The input side has an input matching circuit 2 for matching the impedance of the fundamental frequency between the outside of the input terminal 1 of the high-frequency power amplifier 10 and the high-frequency power amplification transistor 3, and the output of the high-frequency power amplification transistor 3 On the side, an output matching circuit 8 for matching the impedance of the fundamental frequency between the outside of the output terminal 9 of the high frequency power amplifier 10 and the high frequency power amplification transistor 3 is provided.

  The power supply line 5 has an electrical length of λ / 4 of the fundamental wave and a characteristic impedance of 20Ω or more so that the impedance of the fundamental frequency seen from the transistor output terminal 4 when viewed from the power supply line 5 appears open. The other end of the power supply line 5 is provided with a power terminal 6 and a low frequency removal circuit 7 having a function of removing an unnecessary signal frequency in a frequency band lower than the fundamental frequency.

In the low frequency elimination circuit 7, a plurality of GND capacitors 71 connected to the ground are connected between the power supply line 5 and the power supply terminal 6, and an inductor (or microwave transmission line) 72 is connected in series to each bypass capacitor 71. It is connected. Now, the inductive reactance L of the inductor (or microwave transmission line) 72, the inductive reactance L of the power supply line 5, and the capacitance C of the Mth (M is an integer from 2 to m) bypass capacitor 71. When the resonance frequency determined by F (m) and the fundamental frequency is f0,
F (m) <f0
The inductive reactance L of the inductor (or microwave transmission line) 72 connected in series with the capacitance C of the bypass capacitor 71 is adjusted so that the resonance frequency F (m) matches the unnecessary signal frequency to be removed under the condition satisfying Circuit configuration.

  Further, the bypass capacitor 71 and the inductor (or microwave transmission line) 72 directly connected to the bypass capacitor 71 have the same function even if the order of connection is reversed.

  Next, the effect of the low frequency removing circuit 7 in the first embodiment will be described. In FIG. 2, the fundamental frequency of the high-frequency power amplifier 10 of FIG. 1 shown in the first embodiment is set to 800 MHz, and the conventional low-frequency elimination circuit 7 includes only a conventional bypass capacitor (see FIG. 11) and the first embodiment. Comparison with a circuit in which an inductor 72 is connected in series to a bypass capacitor 71 is shown.

  In graph A of FIG. 2, only a general bypass capacitor of 1000 pF is connected, in graph B, 1000 pF + 30 pF is connected as a bypass capacitor, and in graph C, a bypass capacitor of 1000 pF and 6 nH and a series connection circuit of an inductor and a bypass capacitor of 30 pF are connected. A transmission characteristic S21 to the output terminal 9 of the output matching circuit 8 viewed from the transistor output terminal 4 when grounded is shown.

  In graph B of FIG. 2, the capacitance of the bypass capacitor is set to 30 pF so that the resonance frequency is about 400 MHz, but in graph B, a change due to the resonance frequency cannot be confirmed. This is because the power supply line 5 set to the λ / 4 length of the fundamental wave opens the impedance of the fundamental frequency viewed from the transistor output terminal 4, so that the impedance near the fundamental frequency is also raised, thereby bypassing It is difficult to obtain the effect by using the self-resonance of the capacitor.

  Graph C in FIG. 2 shows that by connecting an inductor of 6 nH in series with a 1000 pF bypass capacitor, the inductor is added to the self-resonance of the 1000 pF bypass capacitor, and the resonance frequency shifts to a lower frequency. The Q value of this resonance As a result of this improvement, the parallel resonance by the 6 nH inductor and the 30 pF bypass capacitor and the resonance effect of the power supply line 5, a notch that attenuates a gain of about 5 dB at about 400 MHz can be confirmed.

Thus, in the graph C of FIG. 2 shown in the first embodiment, two bypass capacitors are grounded to the low frequency elimination circuit 7, and an inductor is connected in series to one of the bypass capacitors.
F (m) <f0
The low frequency noise is removed by adjusting one resonance frequency F (1) to several tens of MHz under the condition that satisfies the above condition, and the fundamental wave is generated by adjusting another resonance frequency F (2) to 400 MHz. Suppression of 1/2 oscillation spurious is realized.

  In the description of FIG. 2, an inductor is shown as the inductor (or microwave transmission line) 72 directly connected to the bypass capacitor 71. However, the same effect can be obtained even with a microwave transmission line having a similar inductive reactance component. It is done.

  Next, in FIG. 3, the fundamental frequency of the high-frequency power amplifier 10 of FIG. 1 shown in the first embodiment is 800 MHz, the electrical length of the power supply line 5 is λ / 24 length, the characteristic impedance is 53Ω, and the power supply line 5 In the circuit configuration in which the impedance on the power supply terminal 6 side viewed from the high frequency power amplification transistor 3 is adjusted to a high impedance, preferably open, by the parallel capacitor of the output matching circuit 8, a comparison similar to FIG. 2 is shown.

  3, only a general 1000 pF bypass capacitor is connected to the graph A, 1000 pF + 270 pF is connected to the graph B as a bypass capacitor, and a 1000 pF and 3 nH bypass capacitor and a series connection circuit of inductors +82 pF are connected to the graph C. A transmission characteristic S21 to the output terminal 9 of the output matching circuit 8 viewed from the transistor output terminal 4 when grounded is shown.

  In the graph B of FIG. 3, the capacitance of the bypass capacitor is set to 270 pF so that the resonance frequency is about 400 MHz. In the graph B, the change due to the resonance frequency is a power supply line compared to the graph B of FIG. From the influence of the short electrical length of 5, it is possible to confirm the attenuation that seems to be a little notch. However, as with graph B in FIG. 2, it is difficult to obtain an effect of removing and suppressing unnecessary signals by using the self-resonance of the bypass capacitor.

  Graph C in FIG. 3 shows that by connecting a 3 nH inductor in series with a 1000 pF bypass capacitor, the inductor is added to the self-resonance of the 1000 pF bypass capacitor, and the resonance frequency shifts to a lower frequency. The notch that attenuates the gain of about 18 dB at about 400 MHz can be confirmed by the improvement of the above and the parallel resonance by the 3 nH inductor and the 82 pF bypass capacitor and the resonance effect of the power supply line 5.

Thus, in the graph C of FIG. 3 shown in the first embodiment, two bypass capacitors are grounded to the low frequency elimination circuit 7, and an inductor is connected in series to one of the bypass capacitors.
F (m) <f0
Low frequency noise removal is performed by adjusting one resonance frequency F (1) to several tens of MHz under the condition that satisfies the above condition, and high frequency power amplification is performed by adjusting another resonance frequency F (2) to 400 MHz. It is possible to suppress the 1/2 oscillation spurious of the fundamental wave, which is one of the main problems.

  Further, in FIG. 4, the fundamental frequency of the high-frequency power amplifier 10 of FIG. 1 shown in the first embodiment is set to 800 MHz, the electrical length of the power supply line 5 is set to λ / 4 length, and unnecessary 3 by the low-frequency removing circuit 7 is used. An example of removing two low frequency signals is shown.

  In graph A of FIG. 4, only a general 1000 pF as a bypass capacitor is connected, and in graph B, three series connection circuits of 1000 pF, 10 nH, 82 pF, 9 nH, 30 pF and 1 nH are connected and grounded as a bypass capacitor and an inductor. The transmission characteristic S21 from the transistor output terminal 4 to the output terminal 9 of the output matching circuit 8 is shown.

  Graph B in FIG. 4 adjusts the value of the inductor connected in series with each bypass capacitor in order to adjust the resonance frequency to 30 MHz for 1000 pF, 200 MHz for 82 pF, and 400 MHz for 30 pF. With this circuit configuration, the notch due to the resonance of 1000 pF has a shift of the resonance frequency to a lower frequency due to the influence of the inductor and the Q value compared to the case where only one bypass capacitor of 1000 pF in the graph A shown in FIG. 4 is mounted. The notch due to the resonance of 82 pF can confirm the attenuation of the gain of about 5 dB at 200 MHz, and the notch due to the resonance of 30 pF can confirm the attenuation of the gain of about 2 dB at 400 MHz.

Thus, in the graph B of FIG. 4 shown in the first embodiment, the inductor is connected in series to the three bypass capacitors to the low frequency elimination circuit 7 and grounded.
F (m) <f0
The low frequency noise is removed by adjusting one resonance frequency F (1) to 30 MHz under the condition that satisfies the above conditions, and the other two resonance frequencies F (2) and F (3) are adjusted to 200 MHz and 400 MHz. Thus, it is possible to suppress the 1/4 wave and 1/2 oscillation spurious of the fundamental wave, which is one of the main problems of the high frequency power amplifier 10.

  As described above, the low frequency elimination circuit 7 having a plurality of bypass capacitors 71 connected in series with the inductors 72 shown in FIG. 1 enables a plurality of unnecessary frequencies such as a reception band noise frequency and unnecessary oscillation spurious at a frequency lower than the fundamental wave. It is possible to remove low frequency signals.

  In FIG. 1, the inductor 72 is selected as the inductive reactance connected in series with the bypass capacitor 71. However, the same effect can be obtained by using a microwave transmission line having a distributed constant. Furthermore, in a series connection circuit of a plurality of bypass capacitors 71 and inductors (or microwave transmission lines) 72, when the inductor becomes large, the Q of parallel resonance is improved, and the low frequency band between the resonance frequencies of the plurality of bypass capacitors 71 is improved. There is a problem that the gain increases. In this case, improvement can be made by adding a resistance component to the inductor (or microwave transmission line) 72 connected in series to the bypass capacitor 71.

  For example, as shown in FIG. 5A, when a resistor 73 is connected in series to an inductor 72 connected in series to a bypass capacitor 71, if the resistance value is increased beyond the limit, the resonance Q value is reduced. Since the effect of low frequency removal according to the present invention cannot be obtained, 10Ω or less is desirable.

  Further, as shown in FIG. 5B, when the resistor 74 is connected in parallel to the inductor 72 connected in series to the bypass capacitor 71, if the resistance value is reduced below the limit, the resonance Q value is decreased. Since the low frequency removal effect of the present invention cannot be obtained, 5Ω or more is desirable.

  As described above, by using the low-frequency elimination circuit 7 shown in the first embodiment, in a high-frequency amplifier used in the field of wireless communication where multimode / multibanding is progressing, reception in a frequency band lower than the fundamental frequency is possible. Unnecessary signal frequencies such as band noise and oscillation spurious can be removed and suppressed, and communication quality can be improved.

(Second Embodiment)
FIG. 6 is a diagram showing a low frequency elimination circuit installed at the power supply terminal of the high frequency power amplifier according to the second embodiment of the present invention. The second embodiment will be described with reference to the drawings.

  In the low frequency rejection circuit 7 shown in FIG. 6, a series connection circuit of a plurality of inductors (or microwave transmission lines) 72 and a bypass capacitor 71 is connected by a microwave transmission line 75 (consisting of a plurality of microwave transmission lines). It is a configuration.

  In FIG. 1 shown in the first embodiment described above, a series connection circuit of a plurality of inductors (or microwave transmission lines) 72 and a bypass capacitor 71 included in the low frequency elimination circuit 7 includes a power supply line 5 and a power terminal 6. Although all the circuits are short-circuited in terms of high frequency at the connection point, the low-frequency elimination circuit 7 shown in FIG. 6 connects the series connection circuits of the bypass capacitors 71 with the microwave transmission line 75. The power supply line 5 and the power supply terminal 6 can be connected anywhere as long as they are on the micro transmission line 75 (between a plurality of microwave transmission lines) of the low-frequency elimination circuit 7, and the degree of freedom in layout in circuit design can be increased. It is possible to raise. Further, the effect as the low frequency elimination circuit 7 is the same as that of the first embodiment, and only the microwave transmission line 75 is added to the parameter of the resonance frequency of each bypass capacitor.

  Furthermore, as shown in the bypass capacitor 71A of FIG. 6, when the inductive reactance L component of the inductor (or microwave transmission line) 72 and the microwave transmission line 75A connected in series is equivalent, the inductor (or It is possible to obtain the same effect as the low frequency elimination circuit only by the microwave transmission line 75A without mounting the microwave transmission line 72).

  As described above, in the high-frequency amplifier used in the wireless communication field in which multimode and multiband advancement is performed while increasing the degree of freedom in circuit design by using the low frequency elimination circuit 7 shown in the second embodiment, Unnecessary signal frequencies such as reception band noise and oscillation spurious in a frequency band lower than the fundamental frequency can be removed and suppressed, and communication quality can be improved.

(Third embodiment)
FIG. 7 is a diagram showing a low frequency elimination circuit installed at the power supply terminal of the multiband high frequency power amplifier according to the third embodiment of the present invention. The third embodiment will be described with reference to the drawings.

  FIG. 7 is a diagram showing a basic configuration of a multiband high-frequency power amplifier equipped with a plurality of high-frequency power amplifiers in the first embodiment sharing the low-frequency elimination circuit 7 and the power supply terminal 6. A plurality of high frequency power amplifiers 10 (10A, 10B,..., 10N) shown in FIG. 7 are amplified by each device at each output terminal 4 (4A, 4B,..., 4N) of the high frequency power amplification transistor 3 included therein. The power supply line 5 (5A, 5B,..., 5N) has a λ / 4 length of the fundamental wave frequency and a characteristic impedance of 20Ω or more, and each power supply line 5 shares one power supply terminal 6 It is a structure to do. The power supply terminal 6 is provided with a low frequency removal circuit 7 having the same function as that shown in the first embodiment. The low frequency rejection circuit 7 is provided with at least one GND grounded bypass capacitor 71 with respect to one power supply line 5, and the bypass capacitor 71 connects an inductor (or microwave transmission line) 72 in series as necessary. It becomes the composition which did.

However, the resonance frequency determined by the inductive reactance L of the inductor (or the microwave transmission line) 72, the inductive reactance L of the power supply line 5, and the capacitance C of the plurality of bypass capacitors 71 is F (m), When the lowest frequency among the fundamental frequencies amplified by the high-frequency power amplifier is f0,
F (m) <f0
The inductive reactance L of the inductor (or microwave transmission line) 72 connected in series with the capacitance C of the bypass capacitor 71 is adjusted so that the resonance frequency F (m) matches the unnecessary signal frequency to be removed. Take circuit configuration.

  In the multiband high-frequency power amplifier shown in FIG. 7, the impedance on the power supply terminal 6 side viewed from each high-frequency power amplification transistor 3 is open at the fundamental frequency amplified by the plurality of high-frequency power amplifiers 10 by such a configuration. Therefore, the impedance of each other does not affect each other through the commonly connected low frequency elimination circuit 7, and the power source terminal 6 is shared, and the lowest frequency among the fundamental frequencies that are amplified by the plurality of high frequency power amplifiers 10 mounted therein. It has a function of removing unnecessary signal frequencies in a lower frequency band.

  In addition, since the influences of impedance when they are connected in common do not affect each other, the plurality of high frequency power amplification transistors 3 sharing the low frequency elimination circuit 7 and the power supply terminal 6 are transistors of different stages of each high frequency power amplifier. Or the thing of the same step may be sufficient.

  In the third embodiment, an effect equivalent to that of the graph C in FIG. 2, the graph C in FIG. 3, and the graph B in FIG. 4 shown in the first embodiment can be obtained. This is because each power supply line 5 shown in FIG. 7 is designed to have a λ / 4 length of each fundamental frequency amplified by each high frequency power amplifier 10 so that the impedance on the power source side is high impedance at each fundamental frequency. Therefore, the transmission characteristic S21 of the signal line viewed from the output terminal 4 of each high frequency power amplification transistor 3 is designed to take a peak at each fundamental frequency.

Further, the bypass capacitors 71 connected corresponding to the respective power supply lines 5 are resonance frequencies of inductors (or microwave transmission lines) 72 connected in series with the respective bypass capacitors 71 and inductive reactance components of the power supply lines 5. Is
F (m) <f0
Therefore, the influence of the resonance frequency of each bypass capacitor 71 does not appear in the fundamental frequency band of the above-described pass characteristic S21. As in the first embodiment, the effect of resonance of the bypass capacitor 71 can be obtained only in a frequency band lower than the fundamental frequency.

  However, if the characteristic impedance of each power supply line 5 is smaller than 20Ω, it becomes difficult to bring the fundamental wave impedance to a high impedance even if the desired length of the fundamental wave is λ / 4 as the electrical length. It is difficult to provide a stable multiband high-frequency power amplifier according to the third embodiment in which the impedances of the amplifiers influence each other and the power supply terminals are shared. Therefore, the characteristic impedance of each power supply line 5 is desirably designed with 20Ω or more secured.

  Further, when the electrical length of each power supply line 5 cannot secure the λ / 4 length of the desired fundamental frequency, a capacitor connected in parallel in the output matching circuit 8 of each high frequency power transistor 3 is used. Thus, the fundamental impedance on the power source side viewed from the output terminal 4 of the high frequency power amplification transistor 3 can be designed to be high impedance, preferably open. However, if the electrical length of each power supply line 5 becomes shorter than the desired fundamental frequency λ / 28 length, it becomes difficult to increase the fundamental impedance on the power source side as viewed from the transistor output terminal 4 to 50Ω or more. The impedance between the power amplifiers affects each other, and it is difficult to provide a stable multiband high-frequency power amplifier according to the third embodiment in which the power supply terminals are shared. Therefore, the electrical length of each power supply line 5 is preferably designed with a length of λ / 28 or more secured.

  In addition, when a large number of bypass capacitors and inductive reactance series-connected circuits of the low frequency rejection circuit 7 are included, gain may increase due to parallel resonance. However, as shown in the first embodiment, resistance to inductive reactance is increased. It can be improved by connecting the components in series or in parallel.

  Furthermore, in the configuration example of the low-frequency rejection circuit 7 of the multiband high-frequency power amplifier shown in FIG. 7, at least one bypass capacitor 71 grounded to one power supply line 5 is installed. When the bypass capacitor 71 can be strongly grounded to GND in terms of high frequency, even if one bypass capacitor 71 is shared with respect to two or more power supply lines 5, the load impedance of the mutual high frequency power amplification transistor 3 is increased. Therefore, the low frequency removal circuit 7 need only have the minimum number of bypass capacitors 71 necessary for removing a desired low frequency signal.

  In this way, the impedance on the power source side seen from the output terminal 4 of the high frequency power amplification transistor 3 shown in the third embodiment is a high impedance of 50Ω or more, preferably the power supply line 5 is designed to be open, the bypass capacitor, In the multi-band high-frequency amplifier used in the field of wireless communication where multimode / multi-band conversion is advanced by using the low-frequency elimination circuit 7 in which the resonance frequency with the inductive reactance component is lower than the fundamental frequency, each high-frequency power amplifier By sharing the power supply terminal 6 of the ten high frequency power amplification transistors 3, it is possible to reduce the power supply terminals of the multiband high frequency amplifier, and further, the reception band noise in a frequency band lower than the fundamental frequency, Unnecessary signal frequency such as oscillation spurious can be removed and suppressed, and communication quality It is possible to realize an improvement.

(Fourth embodiment)
FIG. 8 is a diagram showing a low frequency elimination circuit installed at the power supply terminal of the multiband high frequency power amplifier according to the fourth embodiment of the present invention. The fourth embodiment will be described with reference to the drawings.

  FIG. 8 shows a multiband high-frequency power amplifier equipped with a plurality of high-frequency power amplifiers according to the third embodiment sharing the low-frequency rejection circuit 7 and the power supply terminal 6, and a plurality of low-frequency rejection circuits 7 according to the second embodiment. FIG. 2 is a diagram showing a configuration of a dual-type multiband high-frequency power amplifier that has a configuration in which bypass capacitors 71 are connected by a microwave transmission line 75 and amplifies two different frequencies.

  As shown in FIG. 8, the high frequency power amplification transistor 3 has a fundamental frequency of 800 MHz, and the high frequency power amplification transistor 13 has a fundamental frequency of 2 GHz. As in the high frequency amplifier described in the first embodiment, an input matching circuit is provided. 2 and 12, power supply lines 5 and 15, and output matching circuits 8 and 18 are designed.

  The power supply line 5 is designed so that the fundamental wave impedance viewed from the output terminal 4 of the high frequency power amplification transistor 3 is a high impedance of 50Ω or more, preferably open, and similarly, the power supply line 15 is the high frequency power amplification transistor 13. The fundamental impedance viewed from the output terminal 14 is designed to be a high impedance of 50Ω or higher, preferably open, and the two power supply lines 5 and 15 are a power supply common line (microwave transmission line 75) of the low frequency elimination circuit 7. And a common power supply terminal 6 is commonly connected to this connection point.

  A connection point between the power common line (microwave transmission line 75) and the power supply line 5 has a bypass capacitor 71B of the high-frequency power amplification transistor 3, and the power common line (microwave transmission line 75) and the power supply line. The connection point 15 has a bypass capacitor 71C of the high frequency power amplification transistor 13, and is a dual type multiband high frequency power amplifier that amplifies two different frequencies.

  When the bypass capacitors 71B and 71C of the low frequency rejection circuit 7 of FIG. 8 are applied to the configuration shown in FIG. 6 of the second embodiment, one of the bypass capacitors 71 is the bypass capacitor 71B and is grounded to the power supply terminal 6 side. The bypass capacitor 71A becomes the bypass capacitor 71C.

  In FIG. 9, when 120 pF is installed in the bypass capacitor 71B and 1000 pF is installed in the bypass capacitor 71C, the power common line (microwave transmission line 75) is a microwave transmission line having characteristic impedance of 66Ω and the line width is 100 μm and the line length is 4000 μm. , The pass characteristic S21 from the output terminal 4 of the 800 MHz high frequency power amplification transistor 3 to the output terminal of the high frequency power amplifier is shown in graph A of FIG. 9 from the output terminal 14 of the 2 GHz high frequency power amplification transistor 13 to the high frequency power amplifier. The pass characteristic S21 to the output terminal is shown in graph B of FIG.

  When the low frequency elimination circuit 7 is seen from the high frequency power amplification transistor 3 side, a notch is formed at 400 MHz due to the parallel resonance of the bypass capacitor 71B and the power common line (microwave transmission line 75) and the series resonance of the power supply line 5. The bypass capacitor 71C has a self-resonant frequency of 1000 pF of the bypass capacitor 71C due to the series resonance of the power supply common line (microwave transmission line 75) and the power supply line 5. Since it is moving to a low frequency, it is possible to remove noise at a lower frequency.

  Further, when the low frequency elimination circuit 7 is viewed from the high frequency power amplification transistor 13 side, the resonance circuit of the bypass capacitor 71C, the power supply common line (microwave transmission line 75) and the bypass capacitor 71B, and the power supply line 15 are connected in series. A notch is created at 100 MHz by resonance, and the bypass capacitor 71B resonates due to series resonance with the power supply common line (microwave transmission line 75) and the power supply line 15, but not so much as to create a notch with pass characteristics.

  In the circuit example shown in FIG. 8, the effect of removing unnecessary spurious at a low frequency is obtained with respect to 800 MHz, but in order to show the effect with respect to 2 GHz, the power supply line 15 and the bypass capacitor 71C are further connected. This is possible by adding a power supply common line and adding a bypass capacitor at the contact point between the line and the power supply line 15.

  As described above, the power supply common line connecting the plurality of bypass capacitors of the low frequency rejection circuit 7 shown in the fourth embodiment can increase the degree of freedom of the board design layout. By making the resonance between the inductive reactance component and the bypass capacitor function as a low-frequency rejection circuit, it is possible to reduce the number of inductors necessary to create the resonance, and wireless communication is progressing in multimode and multiband. In a high frequency amplifier used in the field, unnecessary signal frequencies such as reception band noise and oscillation spurious in a frequency band lower than the fundamental frequency can be removed and suppressed, and communication quality can be improved.

  As described above, according to the present invention, in addition to the output matching circuit and the power supply line which are designed to have a fundamental impedance viewed from the output terminal of the high frequency power amplifying transistor as viewed from the power supply side to a high impedance of 50Ω or more, the power supply terminal has 2 Used in high-frequency power amplifiers with one or more stages having a low-frequency rejection circuit having one or more bypass capacitors, and further used in the wireless communication field by sharing a low-frequency rejection circuit and a power supply terminal by a plurality of high-frequency power amplifiers It is useful as a technique for performing stable and high-quality communication of a multiband high-frequency power amplifier, particularly a transmitter.

The figure which shows the low frequency removal circuit installed in the power supply terminal of the high frequency power amplifier which concerns on 1st Embodiment of this invention. The figure which shows the effect of the low frequency removal circuit (electrical length is (lambda) / 4 length) in this 1st Embodiment, and graph A, B, C The figure which shows the effect of the low frequency removal circuit (electrical length is (lambda) / 24 length), graph A, B, C in this 1st Embodiment. The figure which shows the effect (three types of notches) and graph A, B of the low frequency removal circuit (electrical length is (lambda) / 4 length) in this 1st Embodiment. (A) is added in series to the conductive reactance induced by the low frequency elimination circuit in the first embodiment, and (b) is a parallel resistor connection example. The figure which shows the low frequency removal circuit installed in the power supply terminal of the high frequency power amplifier which concerns on 2nd Embodiment of this invention. The figure which shows the low frequency removal circuit installed in the power supply terminal of the multiband high frequency power amplifier which concerns on 3rd Embodiment of this invention. The figure which shows the low frequency removal circuit installed in the power supply terminal of the multiband high frequency power amplifier which concerns on 4th Embodiment of this invention. The figure which shows the effect of the low frequency removal circuit (electrical length is (lambda) / 24 length) in this 4th Embodiment, graph A, B A conventional (a) is a T-type filter, and (b) is a circuit example of a π-type filter. Diagram showing the circuit configuration of a conventional high-frequency power amplifier Diagram showing pass characteristics and graphs A and B of a conventional bypass capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Input terminal 2,12 of high frequency power amplifier Input matching circuit 3,13 Transistor 4 for high frequency power amplification 4,14 Transistor output terminal 5,15 Power supply line 6, Power supply terminal 7, Low frequency elimination circuit 8,18 Output matching circuit 9 19 High frequency power amplifier output terminal 10 High frequency power amplifier 71 Low frequency rejection circuit bypass capacitor 72 Low frequency rejection circuit inductor (or microwave transmission line)
73 Series resistor 74 Parallel resistor 75 Microwave power transmission line (Common power line)

Claims (6)

A high frequency power amplifier composed of a plurality of high frequency power amplification transistors for amplifying a desired high frequency signal,
A power supply line connected to the output terminal of the high-frequency power amplification transistor at the K-th stage (K is an integer from 1 to k);
A low-frequency elimination circuit connected between the power supply line and the power terminal,
The low-frequency rejection circuit includes M (M is an integer from 2 to m) bypass capacitors having one end connected between the power supply line and the power supply terminal and the other end grounded, and the M An inductor (or microwave transmission line) connected in series with at least one of the bypass capacitors,
M resonance frequencies determined by the inductive reactance of the inductor (or the microwave transmission line), the inductive reactance of the power supply line, and the capacities of the M bypass capacitors are lower than the desired high-frequency signal. A high-frequency power amplifier having a function of removing an unnecessary signal frequency in a frequency band lower than the desired high-frequency signal band by the low-frequency elimination circuit.   The low frequency rejection circuit connects one ends of M (M is an integer of 2 to m) bypass capacitors connected to a power supply line by a microwave transmission line, and is connected to the microwave transmission line. 2. The high frequency power amplifier according to claim 1, further comprising a configuration in which the power supply line and the power supply terminal are connected to any one of them. 2. The multi-frequency power amplifier according to claim 1, comprising N (N is an integer from 1 to n), wherein each of the N high-frequency power amplifiers has a function of amplifying desired high-frequency signals having different frequencies. A band high frequency power amplifier,
In the N high-frequency power amplifiers, a power supply line connected to the output terminal of one high-frequency power amplification transistor among a plurality of stages constituting each high-frequency power amplifier;
The N power supply lines are connected to each other, and a low frequency elimination circuit sharing one power supply terminal,
The low-frequency removing circuit supplies power to the plurality of high-frequency power amplification transistors from the one power supply terminal, and further removes an unnecessary signal frequency in a frequency band lower than the desired high-frequency signal band. A multi-band high-frequency power amplifier comprising: 2. The multi-frequency power amplifier according to claim 1, comprising N (N is an integer from 1 to n), wherein each of the N high-frequency power amplifiers has a function of amplifying desired high-frequency signals having different frequencies. A band high frequency power amplifier,
In the N high-frequency power amplifiers, a power supply line connected to the output terminal of one high-frequency power amplification transistor among a plurality of stages constituting each high-frequency power amplifier;
A power common line that includes at least one bypass capacitor at a connection point with each of the N power supply lines, and one end of each of the N bypass capacitors is configured by a microwave transmission line; A low frequency rejection circuit having one power supply terminal connected to any of the common lines,
The low-frequency removing circuit supplies power to the plurality of high-frequency power amplification transistors from the one power supply terminal, and further removes an unnecessary signal frequency in a frequency band lower than the desired high-frequency signal band. A multi-band high-frequency power amplifier comprising: Each power supply line connected to the power terminal has an electrical length of λ / 4 for a desired high frequency signal amplified by each high frequency power amplifier, a characteristic impedance of 20Ω or more,
By means of a bypass capacitor connected to the other end of each power supply line, the impedance on the power supply line side viewed from the output terminal of each high frequency power amplification transistor in the desired high frequency signal is opened, and each high frequency power amplification transistor 5. The multiband high-frequency power amplifier according to claim 3, wherein the multi-band high-frequency power amplifier is configured not to be affected by an external impedance from the bypass capacitor. Each power supply line connected to the power supply terminal has an electrical length of λ / 28 length or more and λ / 4 length or less with respect to a desired high frequency signal amplified by each high frequency power amplifier, a characteristic impedance of 20Ω or more,
An output matching circuit having a grounded parallel capacitor at the output terminal of each high-frequency power amplification transistor connected to each power supply line;
With the capacitor of the output matching circuit and a bypass capacitor connected to the other end of the power supply line, the impedance on the power supply line side viewed from the output terminal of each high frequency power amplification transistor in the desired high frequency signal is opened, 5. The multiband high-frequency power amplifier according to claim 3, wherein each of the high-frequency power amplification transistors is configured not to be affected by an external impedance from the bypass capacitor.

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