CN107222183A - A kind of wide-band microwave switch duplicate circuitry of low video feedthrough leakage - Google Patents

Abstract

The present invention relates to a kind of microwave switch duplicate circuitry, and in particular to a kind of wide-band microwave switch duplicate circuitry of low video feedthrough leakage, including high band port, high band biasing circuit, low band port, low band biasing circuit and public port；High band PIN diode uses cascaded structure, low band PIN diode uses parallel-connection structure, the PIN diode control for switching duplicate circuitry powers up mode using positive negative balance, prior art is solved in switch changes state, the change of bias voltage fast step can produce the video feed-through signal of low frequency, the technical problem that the normal transmission to signal is interfered.

Description

A Broadband Microwave Switching Duplex Circuit with Low Video Feedthrough Leakage

technical field

The invention relates to a microwave switch duplex circuit, in particular to a broadband microwave switch duplex circuit with low video feedthrough leakage.

Background technique

The operating bandwidth of microwave test instruments is getting wider and wider, because of the use of component bandwidth limitations and different processing methods for high and low band signals. In most cases, the transmitting channels of broadband microwave testing instruments are divided into high and low bands for signal generation and processing respectively. In the receiving channel of the signal, it is also necessary to convert and distribute the broadband microwave input signal to channels of different high and low bands for analysis and processing. Now, the minimum operating frequency of microwave and millimeter wave test instruments is getting lower and lower, and the minimum operating frequency of general test instruments is several kilohertz (kHz). In this way, a circuit needs to be implemented in the transmitting and receiving channels of the broadband microwave test instrument, which can convert and synthesize the low-band signal containing the low frequency of several kilohertz (kHz) and the high-band signal of the microwave frequency into one channel for transmission. For output, on the contrary, it is necessary to convert and distribute the wideband received signal including low frequency of several kilohertz (kHz) to channels of different bands of high and low frequencies for analysis and processing respectively. At the same time, due to the requirements of the instrument test speed, this circuit is required to have a faster switching speed.

For converting microwave signals of different channels, there are mainly microwave coaxial electromechanical switches, microwave electronic switches, and microwave switch duplex circuits.

Although the microwave coaxial electromechanical switch has advantages in insertion loss, standing wave at the port, and withstand power, etc., its slow switching speed and limited service life are insurmountable shortcomings. used less and less.

Microwave electronic switches mainly include PIN diode switches and FET switches. Among them, due to the inherent characteristics of the PIN diode, the PIN diode switch has a cut-off frequency limit at low frequency, which limits its use in the low frequency band. Although the FET switch does not have a cut-off frequency limit, there is a problem that the input power compression point decreases when the FET switch transmits low-frequency signals. The lower the frequency, the lower the input power compression point, which also limits its use at low frequencies. Because of the above reasons, when there are low-frequency signals lower than 1MHz-10MHz in the working frequency band in the conversion path, the use of microwave electronic switches is limited.

The microwave switch duplex circuit is suitable for the conversion of signals of different frequency bands in the high and low bands. Generally, the microwave switch duplex circuit uses inductance and capacitance elements to realize the duplex circuit. It is very difficult to achieve when the segmentation point frequency of is high. At the same time, because the segmentation point of the duplex circuit is determined by the capacitance and the inductance, the accuracy error of the capacitance and the inductance will cause the segmentation point of the microwave switch duplexer to shift, and the implementation consistency is poor. At the same time, the microwave switch duplex circuit needs to use a switch control element to achieve high isolation. Generally, a PIN diode is used. The switching of the PIN diode switch in the microwave switch duplex circuit needs to provide a DC bias for positive and negative voltage conversion. During switching transitions, a fast step change in the bias voltage produces a low frequency video feedthrough signal (typically a signal spectrum from DC to several hundred MHZ depending on the drive speed). Because microwave switch duplexers generally need to work at low frequencies or even to direct current (DC), the generated video feedthrough interference will interfere with the normal transmission of signals within the operating frequency of the switch duplex circuit, especially in applications that require fast agility. In instruments and equipment, it has a great impact on the normal use and processing of subsequent signals.

Contents of the invention

The invention provides a broadband microwave switch duplex circuit with low video feedthrough leakage, which solves the problem of low-frequency video feedthrough signal generated by rapid step change of bias voltage in the state of switch conversion in the prior art, and the normal transmission of the signal Interfering technical issues.

The wideband microwave switch duplex circuit with low video feedthrough leakage of the present invention comprises a high-band port, a high-band bias circuit, a low-band port, a low-band bias circuit and a common port, and the high-band bias circuit is arranged at the Between the high-band port and the common port, the low-band bias circuit is arranged between the low-band port and the common port;

The high-band bias circuit includes a first DC-blocking capacitor connected in series with the high-band port, a first PIN diode, and a high-band bias connected in parallel with the high-band port, and the high-band bias passes through the first current limiting A resistor and a choke inductor are connected between the first DC blocking capacitor and the first PIN diode;

The low-band bias circuit includes a low-band coupling inductor connected in series with the low-band port, and a plurality of low-band PIN diodes connected in parallel with the low-band port, the other end of the low-band coupling inductor is connected to a common port, the The low-band PIN diodes are grounded respectively through the low-band DC blocking capacitors, and connected to the low-band bias through the second current-limiting resistor.

Preferably, the resistance values of the first current limiting resistor and the second current limiting resistor are the same. The bias control of the high and low bands has the same absolute value of the bias voltage and opposite polarity, which can offset the influence of the drive control on the microwave channel and reduce the leakage of the video feedthrough.

Preferably, the low-band PIN diode includes a second PIN diode and a third PIN diode, the second PIN diode is grounded through a second DC blocking capacitor, and the third PIN diode is grounded through a third DC blocking capacitor. In order to improve the low-band isolation, the number of low-band PIN diodes connected in parallel can be increased.

Preferably, the low-band coupling inductor is realized by using a microstrip circuit. The coupled inductor operating frequency of the microstrip circuit can be very high, which can increase the operating frequency of the switching duplex circuit.

Preferably, the choke inductance is realized by powered gold wire to achieve a smaller inductance value to adapt to the higher operating frequency of the high-band bias circuit.

Preferably, the first DC blocking capacitor adopts a beam-type lead capacitor, which is suitable for assembly.

Preferably, the low-band DC blocking capacitor is a flat capacitor, and the ground terminal is grounded through a microstrip circuit via hole.

Preferably, the first current limiting resistor and the second current limiting resistor are realized by thin film resistors.

The wideband microwave switch duplex circuit with low video feedthrough leakage of the present invention can realize high and low band conversion synthesis or conversion distribution of broadband signals including extremely low frequency, and the working frequency reaches DC-50GHz, and has a faster switching speed, high and low band The frequency segmentation point can be realized at a higher frequency band point, and the frequency segmentation point can be selected from any frequency in the 5GHz-20GHz frequency band according to the design of the microstrip coupling inductor.

Compared with the prior art, the broadband microwave switch duplex circuit with low video feedthrough leakage of the present invention has the following advantages:

1) Realization of high- and low-band segmentation points at higher frequencies: High-band PIN diodes adopt a series structure to avoid the limitation that small-capacity capacitors are difficult to realize at high-frequency segmentation points, and realize higher-frequency segmentation point frequencies.

2) The circuit structure is simple and the control establishment is small: the high and low band PIN diodes adopt a series-parallel structure, and one bias path realizes full control of the high and low band diodes, the circuit is simple, and the control bias is small.

3) Low video feedthrough leakage: The PIN diode control of the switch duplex circuit adopts the positive and negative balance power supply method, which greatly reduces the video feedthrough leakage generated by the switch drive control, and reduces the impact of video feedthrough on the signal transmission channel signal. influences.

4) Wide frequency band, low insertion loss: The low-band coupling inductor adopts microstrip matching design, and the working frequency is high; the high-band adopts microstrip matching design, which reduces the parasitic parameters generated by series PIN diodes, reduces insertion loss, and improves operating frequency.

5) Good production consistency: The low-band coupling inductance that determines the frequency of the segmentation point is realized by a microstrip circuit, with high processing accuracy and production consistency; the high-band does not use small-capacity capacitors to realize duplex circuits, eliminating the impact of capacitance accuracy on duplex impact on circuit consistency.

Description of drawings

Fig. 1 is the principle diagram of the broadband microwave switch duplex circuit of low video feedthrough leakage of the present invention;

Figure 2 is a schematic diagram of a simplified microwave switch duplex circuit;

Figure 3 is an assembly structure diagram of a DC-50GHz microwave switch duplex circuit (6GHz segment point).

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1:

As shown in Figure 1, the broadband microwave switch duplex circuit with low video feedthrough leakage in this embodiment includes a high-band port 1, a high-band bias circuit, a low-band port 2, a low-band bias circuit and a common port 3, The high-band bias circuit is set between the high-band port 1 and the common port 3, and the low-band bias circuit is set between the low-band port 2 and the common port 3;

The high-band bias circuit includes a first DC blocking capacitor C1 connected in series with the high-band port 1, a first PIN diode D1, and a high-band bias 4 connected in parallel with the high-band port 1, the high-band bias 4 connected between the first DC blocking capacitor C1 and the first PIN diode D1 through the first current limiting resistor R1 and the choke inductor L1;

The low-band bias circuit includes a low-band coupling inductor L2 connected in series with the low-band port 2, and a second PIN diode D2 and a third PIN diode D3 connected in parallel with the low-band port 2, in order to improve the isolation of the low-band , can increase the number of low-band PIN diodes connected in parallel. The other end of the low-band coupling inductor L2 is connected to the common port 3, the second PIN diode D2 and the third PIN diode D3 are grounded through the second DC blocking capacitor C2 and the third DC blocking capacitor C3 respectively, and are grounded through the second limiting capacitor C3. Flow resistor R2 connects to low band bias 5. It can not only ensure the radio frequency grounding, but also add low-band bias voltage.

Further, the resistance values of the first current limiting resistor R1 and the second current limiting resistor R2 in this embodiment are the same. The bias control of the high and low bands has the same absolute value of the bias voltage and opposite polarity, which can offset the influence of the drive control on the microwave channel and reduce the leakage of the video feedthrough.

Further, the low-band coupling inductor L2 in this embodiment is realized by using a microstrip circuit. The coupled inductor operating frequency of the microstrip circuit can be very high, which can increase the operating frequency of the switching duplex circuit.

Further, the choke inductor L1 in this embodiment is realized by a powered gold wire to achieve a smaller inductance value to adapt to the higher operating frequency of the high-band bias circuit.

Example 2:

As shown in Figure 1, the specific working state of the broadband microwave switch duplex circuit with low video feedthrough leakage in this embodiment is: when the high-band bias 4 is applied with a positive voltage, and the low-band bias 5 is added with the same negative voltage, The PIN diodes connected in series with the high-band bias circuit and the PIN diodes connected in parallel with the low-band bias circuit are all turned on, so that the high-band port 1 realizes straight-through, and the low-band port 2 realizes isolation. At the same time, because the voltages of the two control terminals are the same, the potential on the path from the low-band port 2 to the common port 3 remains at zero potential. When the high-band bias 4 is applied with a negative voltage, and the low-band bias 5 is applied with the same positive voltage, the PIN diodes connected in series with the high-band bias circuit and the PIN diodes connected in parallel with the low-band bias circuit are all cut off, so that the high-band port 1 is isolated. Low-band port 2 enables passthrough. At the same time, because the series-parallel PIN diodes are all in the cut-off state, the potential on the path from the low-band port 2 to the common port 3 is also kept at zero potential. In the driving state of the switch, the potential on the path from the low-band port 2 to the common port 3 is kept at zero potential, so the video feedthrough generated by the switch driving can be greatly reduced, and the path from the low-band port 2 to the common port 3 It is possible not to use a DC blocking capacitor to make the switching duplex circuit work to DC.

Example 3:

As shown in FIG. 2 , this embodiment is a schematic diagram of a simplified microwave switch duplex circuit. The PIN diodes are also connected in series and parallel, but the parallel PIN diodes in the low-band bias circuit are directly grounded, so that a relatively simple microwave switch duplex circuit can also be realized.

The specific working principle is: when the switch duplex circuit is biased, there is a DC voltage in the channel of the low-band port 2 and the common port 3, and a DC blocking capacitor needs to be added to the channel. At the same time, the rapid change of the driving voltage will generate a video signal on the channel. Feedthrough leakage. The circuit in Figure 2 can control the microwave switch duplex circuit only through one power-on bias terminal of the high-band bias circuit, and the drive is simple. This circuit is suitable for applications where the influence of video feedthrough leakage is not required or the minimum operating frequency is relatively low. high use.

Example 4:

As shown in Figure 3, this implementation discloses a specific implementation of a broadband microwave switch duplex circuit with low video feedthrough leakage, that is, an assembly structure diagram of a DC-50GHz microwave switch duplex circuit (6GHz segmentation point), wherein The first PIN diode D1, the second PIN diode D2, and the third PIN diode D3 all use beam-type lead PIN diode cores. The capacitor C2 and the third DC-blocking capacitor C3 are planar capacitors, and the ground terminal is grounded through a microstrip circuit via. The first current-limiting resistor R1 and the second current-limiting resistor R2 in the high and low bands are realized by thin-film resistors. The circuit between the first DC blocking capacitor C1 and the first PIN diode D1 is a matching circuit designed by simulation, and its main function is to offset the influence of the first PIN diode D1 connected in series, reduce insertion loss, and increase the operating frequency. The low-band microstrip coupling inductor L2 determines the segmentation point of the high and low bands, and the segmentation point of the high and low bands in Figure 3 is 6GHz. When the microstrip coupling inductance L2 changes, the segmentation points of the high and low bands can be changed.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the application, some modifications can also be made. Improvement and retouching, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention shall be deemed to be included in the protection scope of the present invention.

Claims (8)

1. a kind of broadband microwave switch duplex circuit that low video feedthrough leaks, it is characterized in that: comprise high-band port, high-band bias circuit, low-band port, low-band bias circuit and common port, described high-band bias The setting circuit is arranged between the high-band port and the common port, and the low-band bias circuit is arranged between the low-band port and the common port; The high-band bias circuit includes a first DC-blocking capacitor connected in series with the high-band port, a first PIN diode, and a high-band bias connected in parallel with the high-band port, and the high-band bias passes through the first current limiting A resistor and a choke inductor are connected between the first DC blocking capacitor and the first PIN diode; The low-band bias circuit includes a low-band coupling inductor connected in series with the low-band port, and a plurality of low-band PIN diodes connected in parallel with the low-band port, the other end of the low-band coupling inductor is connected to a common port, the The low-band PIN diodes are grounded respectively through the low-band DC blocking capacitors, and connected to the low-band bias through the second current-limiting resistor. 2 . The broadband microwave switching duplex circuit with low video feedthrough leakage according to claim 1 , wherein the resistance values of the first current limiting resistor and the second current limiting resistor are the same. 3 . 3. The wideband microwave switch duplex circuit of a kind of low video feedthrough leakage as claimed in claim 1, characterized in that: the low-band PIN diode comprises a second PIN diode and a third PIN diode, and the second PIN diode The diode is grounded through the second DC blocking capacitor, and the third PIN diode is grounded through the third DC blocking capacitor. 4. A broadband microwave switch duplex circuit with low video feedthrough leakage according to any one of claims 1-3, characterized in that: the low-band coupling inductor is realized by a microstrip circuit. 5. A broadband microwave switch duplex circuit with low video feedthrough leakage according to any one of claims 1-3, characterized in that: the choke inductance is realized by a powered gold wire. 6 . The broadband microwave switching duplex circuit with low video feedthrough leakage according to claim 1 , wherein the first DC blocking capacitor is a beam lead capacitor. 6 . 7. A broadband microwave switching duplex circuit with low video feedthrough leakage according to any one of claims 1-3, characterized in that: the low-band DC blocking capacitor is a flat capacitor. 8. A broadband microwave switch duplex circuit with low video feedthrough leakage according to any one of claims 1-3, characterized in that: the first current-limiting resistor and the second current-limiting resistor are thin-film resistors accomplish.