KR100263179B1 - Apparatus for generating intermediate frequency in portable radio receiver capable of using in multimode or multi-band - Google Patents

Abstract

The present invention relates to an intermediate frequency generator of a portable wireless receiver usable in multimode multiband.

The intermediate frequency generator includes a phase detector for outputting a phase detection signal by comparing a reference frequency signal with a predetermined input frequency signal, and one-to-one correspondence with each band, and a band-specific loop for removing noise and high frequency with respect to the phase detection signal. A switch for selecting one of the band-specific loop filters according to a predetermined band selection signal and transferring the output of the phase detection unit, and connected to an output terminal of the loop filters, and selected to lower a relative frequency change ratio between bands. A tank circuit for generating a signal having a frequency that is a specific integer multiple of a band specific frequency for each band, a voltage controlled oscillator for outputting an oscillation signal of a predetermined frequency according to a signal output through the tank circuit, and receiving a predetermined control The division ratio is changed, and the output of the voltage controlled oscillator is divided according to the division ratio. By a frequency divider to pass to the phase detector, the output of the voltage controlled oscillator a predetermined intermediate frequency signal and mixing the phosphorus-characterized in the adapted parts of the baseband signal generator for generating a phase and a quadrature base band communication signal.

Description

Intermediate Frequency Generator of Portable Wireless Receiver for Multimode Multiband

The present invention relates to an intermediate frequency generator of a portable radio receiver for receiving and demodulating radio frequencies in a mobile communication system, and more particularly, to an intermediate frequency generator of a receiver usable in a multimode multiband.

Typically, when the number of bands or bands of a wireless communication is changed, the accompanying intermediate frequency (hereinafter referred to as IF) voltage-controlled oscillator (hereinafter referred to as VCO) and its peripheral circuits must also be changed. That is, two VCOs are required in a dual band and three VCOs are required in a triple band.

For example, U.S. The PCS CDMA band requires an Rx IF of 210.38MHz and the cellular band requires an Rx IF of 85.38MHz. As the IF of the signal for each band is different as described above, to implement a terminal that can be used in both the PCS band and the cellular band, a processing circuit corresponding to each method must be separately provided.

1 is a view showing the configuration of a conventional portable radio receiver intermediate frequency generator that can be used in a dual band.

The illustrated portable radio receiver is a dual band and includes a phase detector 110, a first part 100, and a second part 200. The basic structure of the first portion 100 and the second portion 200 is the same. In case of implementing a receiver usable in the triple band, a third part (not shown) having the same structure may be further provided.

The phase detection unit 110 outputs a phase detection signal by comparing a reference frequency signal obtained by dividing a signal output from the TCXO 108 by a predetermined division (÷ R) in the first divider 109 with a predetermined input frequency signal. Herein, the input frequency signal means that the input frequency signal is input from the first or second portions 100 and 200 according to which of the bands is set. Therefore, the phase detection signal may also be output to the first or second portions 100 and 200 according to the set band. The first switch SW1 serves to connect the phase detector 110 and the first or second parts 100 and 200 according to a band selection signal BS. Hereinafter, the case where the first switch SW1 is connected to the first portion 100 will be described.

The loop filter 111 outputs a constant DC component by removing noise and high frequency of the phase detection signal. The loop filter 111 is designed according to the IF, the comparison frequency, and the phase detection signal (current) of each band inside the phase detection unit 110. The tank circuit 112 is connected to the output end of the loop filter 111. The tank circuit 112 is composed of a resistor, a condenser, a varactor, and the like, and determines a resonance frequency. The signal output from the loop filter 111 is a varactor tuning voltage of the tank circuit 112. The VCO 113 outputs an oscillation signal of a predetermined frequency according to a signal output through the tank circuit 112, that is, a control voltage. The second divider 114 divides the output of the VCO 113 into a predetermined frequency and transfers the output to the phase detector 110. The loop filter 111, the tank circuit 112, the VCO 113, the second divider (÷ n) 114 and the phase detector 110 described above implement a phase locked loop (hereinafter referred to as a PLL). The second divider ÷ n 114 is provided with a different value depending on the band.

Referring to the baseband signal generator, the first mixer 117 mixes the intermediate frequency signal IF1 which is the first input and the predetermined second input to output the in-phase baseband communication signal I. The second mixer 118 mixes the intermediate frequency signal IF1 which is the first input and the predetermined second input to output the quadrature baseband communication signal Q. The divider 115 divides the output of the VCO 113 into two and provides it as a second input of the first and second mixers 117 and 118, respectively. A 90 degree phase shifter 116 phase shifts the output of the distributor 115 by 90 degrees to the second mixer 118. The second switch SW2 serves to connect the VCO 113 of the first part 100 or the VCO 121 of the second part 200 with the distributor 115 according to the band selection signal BS.

However, when the configuration and operation as described above, as shown, even if only the first part 100 and the second part 200 are seen, there are several overlapping elements. Therefore, it is much less competitive in terms of price and weight.

Accordingly, an object of the present invention is to provide an intermediate frequency generator of a portable radio receiver capable of demodulating radio frequencies received in a multimode multiband in a single structure.

According to the present invention for achieving the above object, the intermediate frequency generator includes a phase detector for outputting a phase detection signal by comparing a reference frequency signal with a predetermined input frequency signal, and one-to-one correspondence with each band, A band-specific loop filter for removing noise and high frequency, a switch for selecting one of the band-specific loop filters according to a predetermined band selection signal, and transferring the output of the phase detector, and an output terminal of the loop filters, A tank circuit for generating a signal having a frequency that is a certain integer multiple of the band inherent frequency for each selected band in order to lower the relative frequency change rate between the bands, and outputs an oscillation signal of a predetermined frequency in accordance with the signal output through the tank circuit A voltage controlled oscillator and a frequency division rate under a predetermined control, and the voltage controlled oscillator A divider for dividing the output of the device according to the division ratio and delivering it to the phase detector, and a base for generating in-phase and quadrature baseband communication signals by mixing the output of the voltage controlled oscillator with a predetermined intermediate frequency signal. Characterized in that the band signal generator.

1 is a view showing the configuration of a conventional portable wireless receiver intermediate frequency generator that can be used in a dual band

2 is a diagram illustrating a configuration of a portable radio receiver intermediate frequency generator that can be used in a multi-mode multi-band according to a first embodiment of the present invention.

3 is a diagram illustrating an example of a configuration of a loop filter used in FIG. 2.

4 is a diagram illustrating a configuration of a portable radio receiver intermediate frequency generator that can be used in a multi-mode multi-band according to a second embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, numerous specific details such as components of specific circuits are shown, which are provided to help a more general understanding of the present invention, and it is understood that the present invention may be practiced without these specific details. It will be self-evident to those of ordinary knowledge. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

FIG. 2 is a diagram illustrating a configuration of a portable radio receiver intermediate frequency generator that can be used in a multimode multiband according to a first embodiment of the present invention.

The phase detector 210 compares the signal output from the TCXO 108 with a predetermined frequency divided by a predetermined frequency (÷ R) in the first divider 109 and outputs a phase detection signal.

Loop filters 111 to 119 corresponding to each band eliminate noise and high frequency of the phase detection signal. Each of the loop filters 111 to 119 is designed according to the IF, the comparison frequency, and the phase detection signal (current) of each band inside the phase detection unit 110.

The first switch SW1 selects one of the loop filters 111 to 119 according to the band selection signal BS to transfer the output of the phase detector 110. The band selecting means for generating the band selection signal BS is a main control part such as a mobile station modem (MSM).

The tank circuit 112 is connected to the output terminals of the loop filters 111 to 119. The tank circuit 112 is an LC parallel resonant circuit, and serves to store most of the energy supplied by the power source during resonance.

The VCO 113 outputs an oscillation signal of a predetermined frequency according to a signal output through the tank circuit 112, that is, a control voltage. The divider 115 divides the output of the VCO 113 by a predetermined amount, and the divider ÷ n 114 divides the output of the VCO 113 by a predetermined amount and transfers the output of the VCO 113 to the phase detector 110.

The switch SW2 described above, the loop filters 111 to 119, the tank circuit 112, the VCO 113, the divider 114 and the phase detector 110 implement a PLL.

The first mixer 117 mixes the intermediate frequency signal IF1 which is the first input and the predetermined second input to output the in-phase baseband communication signal I. The second mixer 118 mixes the intermediate frequency signal IF1 which is the first input and the predetermined second input to output the quadrature baseband communication signal Q. The output of the divider 115 is transmitted to the first mixer 117 as it is, and the second mixer 118 is provided with a 90 degree phase shifted signal through the 90 degree phase shifter 116 as a second input.

3 is a diagram illustrating a configuration example of a loop filter used in FIG. 2.

For example, cellular bands require an Rx IF of 85.38 MHz and U.S. Since the PCS band requires an Rx IF of 210.38 MHz, assuming that the comparison frequency of the phase detector 210 of FIG. 2 is 30 KHz and 5 KHz, the distribution of the reference signal frequency (19.68 MHz) is different to 656 and 3936, respectively. When the frequency of the input signal of the loop filter is changed in this way, the values of the resistors R and the capacitor C constituting the loop filter must also be changed. Table 1 shows the values for each part of the loop filter when the comparison frequency is 30 Hz and 5 Hz. Only the comparison frequency is different and the other factors are the same, and specific values for the other components are shown. For example,

Phase margin: 45 degrees

Loop Bandwidth: 300Hz

Loop Attenuation: 1dB

Kvco: 40 MHz / V

Charge Pump Output Current: 1mA

VCO Output Frequency: 85.38MHz

band Comparison frequency R1 [ KΩ ] R2 [ KΩ ] C1 [nF] C2 [ μ F] C3 [pF] Cellular 30KHz 0.648 20 400 1.96 93 PCS 5KHz 4.8 20 55.8 0.25 0.6

Cellular Signals and U.S. Signals Signals in the PCS band are too large in frequency intervals. So the output frequency of the VCO is much larger than the desired frequency (800MHz or 1800MHz). If it is assumed that the frequency of the CDMA band signal is quadrupled and the frequency of the PCS band signal is doubled, the divider value corresponding to each is set to 4 and 2, and either 4 or 2 is selected according to the set band. In this way, the relative frequency change rate is small, so that both signals can be produced simply by changing the capacitance of the varactor of the tank circuit connected to the front end of the VCO.

Referring to FIG. 2, the divider 115 serves to reduce the rate of change between frequencies of the signal output from the VCO 113. Typically, the output range of a VCO does not cover all of the various frequency bands (for example, in the case of dual bands it is often not possible to include both frequency bands). This role is essential for implementing portable wireless receivers that can be used in multimode multiband as a single VCO.

FIG. 4 is a diagram illustrating a configuration of a portable radio receiver intermediate frequency generator that can be used in a multimode multiband according to a second embodiment of the present invention.

The phase detector 210 compares the signal output from the TCXO 108 with a predetermined frequency divided by a predetermined frequency (÷ R) in the first divider 109 and outputs a phase detection signal. The loop filter 200 removes noise and high frequency with respect to the phase detection signal. The loop filter 200 is designed according to the IF, the comparison frequency, and the phase detection signal (current) of each band inside the phase detection unit 110. The tank circuit 112 is connected to the output end of the loop filter 200. The VCO 113 outputs an oscillation signal of a predetermined frequency according to a signal output through the tank circuit 112, that is, a control voltage. The divider 114 divides the output of the VCO 113 by a predetermined division (÷ n) and transfers the output to the phase detector 110. The loop filter 200, the tank circuit 112, the VCO 113, the divider 114, and the phase detector 110 described above implement a PLL.

A divider 300 is connected to the output terminal of the VCO 113. The frequency divider 300 changes its division ratio ÷ X according to the band selection signal BS generated by the band selection means. Subsequently, the baseband signal generator, that is, the divider 115 divides the output of the divider 300 into the first and mixers 117 and 118 to output the in-phase and quadrature baseband communication signals I and Q as described above. Do.

As a result, according to the second embodiment, unlike the first embodiment described above, only one loop filter is provided. The output terminal of the VCO is connected to a divider whose division ratio (÷ X) changes according to the band type selected, thereby implementing an intermediate frequency generator of a portable wireless receiver that can be used in a multimode multiband.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention enables demodulation of a radio frequency received in a multimode multiband even with a single VCO, thereby reducing the overlapping factor in each band, thereby reducing the economical and light weight.

Claims (8)

An intermediate frequency generator of a portable wireless receiver usable in multimode multiband, A phase detector for comparing a reference frequency signal with a predetermined input frequency signal and outputting a phase detection signal; A band-specific loop filter corresponding to each band one-to-one, and removing noise and high frequency with respect to the phase detection signal; A switch for transmitting one output of the phase detector by selecting one of the loop filters for each band according to a predetermined band selection signal; A tank circuit connected to an output terminal of the loop filters and generating a signal having a frequency that is a certain integer multiple of a frequency inherent to the corresponding band for each selected band in order to lower a relative frequency change rate between bands; A voltage controlled oscillator for outputting an oscillation signal of a predetermined frequency in accordance with the signal output through the tank circuit; A divider ratio is changed under predetermined control, and a divider for dividing the output of the voltage controlled oscillator according to the divide ratio and transferring the divided frequency to the phase detector; And a baseband signal generator configured to generate an in-phase and quadrature baseband communication signal by mixing the output of the voltage controlled oscillator with a predetermined intermediate frequency signal. The method of claim 1, And the band selection signal is generated in a main control part of the wireless receiver. The method of claim 2, And a DC voltage applied to the selector of the tank circuit by adjusting the waveform output from the phase detection unit. The method of claim 2, In the code division multiple access method, the operating frequency of the voltage controlled oscillator is 341.52 MHz, and the division value of the divider is selected as 4. The operating frequency of the voltage controlled oscillator is 420.76 MHz and the divider in the personal mobile communication system. 2 is selected as the division value of. An intermediate frequency generator of a portable wireless receiver usable in multimode multiband, A phase detector for comparing a reference frequency signal with a predetermined input frequency signal and outputting a phase detection signal; A loop filter for removing noise and high frequency with respect to the phase detection signal; A tank circuit connected to an output terminal of the loop filter and generating a signal having a frequency that is a specific integer multiple of a specific frequency of a corresponding band for each selected band in order to lower a relative frequency change rate between bands; A voltage controlled oscillator for outputting an oscillation signal of a predetermined frequency in accordance with the signal output through the tank circuit; A divider ratio is changed under predetermined control, and a divider for dividing the output of the voltage controlled oscillator according to the divide ratio and transferring the divided frequency to the phase detector; A frequency division ratio is changed according to a predetermined band selection signal, and a band-divider for dividing the output of the voltage controlled oscillator according to the frequency division ratio; And a baseband signal generator configured to generate an in-phase and quadrature baseband communication signal by mixing the band-divider output with a predetermined intermediate frequency signal. The method of claim 5, And the band selection signal is generated in a main control part of the wireless receiver. The method of claim 6, And a DC voltage applied to the selector of the tank circuit by adjusting the waveform output from the phase detection unit. The method of claim 7, wherein In the code division multiple access method, the operating frequency of the voltage controlled oscillator is 341.52 MHz, and the division value of the divider is selected as 4. The operating frequency of the voltage controlled oscillator is 420.76 MHz and the divider in the personal mobile communication system. 2 is selected as the division value of.