KR100593928B1 - Gm-c filter with i and q signal compensation - Google Patents

Abstract

It is an object of the present invention to provide a GM-C filter applied to an image rejection mixer of a communication system.

GM-C filter of the present invention, by simply designing a circuit that performs the magnitude and phase compensation for the I signal and the Q signal without using a separate compensation circuit using a GM cell, the separate size and the like of the variable capacitor, variable resistor, etc. Without the phase correction circuit, the magnitude and phase of the I and Q signals can be corrected.

Image Rejection Filter, GM-C Filter

Description

GM-C filter with compensation function {GM-C FILTER WITH I AND Q SIGNAL COMPENSATION}

1 is a block diagram of a conventional image reject mixer.

2 is a frequency spectrum diagram of a desired signal and an image signal.

3 is a vector diagram showing phases of a desired signal and an image signal of an I pass.

4 is a vector diagram showing phases of a desired signal and an image signal of a Q pass.

5 is a block diagram of a GM-C filter according to the present invention.

6 is a configuration diagram of a first gain compensator of the present invention.

7 is a configuration diagram of a second gain compensator of the present invention.

8 is a configuration diagram of a first phase compensator of the present invention.

9 is a configuration diagram of a second phase compensator of the present invention.

10A and 10B are vector diagrams for explaining phase compensation according to the present invention.

Explanation of symbols on the main parts of the drawings

110: first gain compensation unit 111: gain control unit

112: input synthesizer 120: first filter

130: first phase compensation unit 131: gain control unit

132: output combiner 210: second gain compensator

211: gain control unit 212: input synthesis unit

220: second filter 230: second phase compensator

231: gain control unit 232: output synthesis unit

310: size control unit 320: phase control unit

Va; Gain control signal Vp: phase control signal

SI: input I signal SQ: input Q signal

SI1: first I signal SQ1: first Q signal

SI2; Second first signal SQ2: Second Q signal

GC11 to GC18: first to eighth GM cells GC21 to GC28: first to eighth GM cells

The present invention relates to a GM-C filter applied to an image rejection mixer of a communication system, and in particular, simply designs a circuit for performing magnitude and phase compensation on an I signal and a Q signal without a separate compensation circuit using a GM cell. Accordingly, the present invention relates to a GM-C filter having an IQ compensation function capable of correcting the magnitude and phase of an I signal and a Q signal without a separate magnitude and phase correction circuit such as a variable capacitor or a variable resistor.

In general, a receiving unit of a wireless device such as a mobile communication device includes a down converter that mixes a received signal into an oscillation frequency and downconverts it to a frequency such as an IF signal or a baseband signal. An image signal is included in addition to the desired desired signal, and serves as an interference signal of the desired signal.

Here, a mixer that removes even an image signal when downconverting to an IF signal is called an image reject mixer.

One of such image reject mixers will be described with reference to FIG.

1 is a block diagram of a conventional image reject mixer.

The conventional image rejection mixer shown in FIG. 1 includes a divider 11 for distributing an input signal, and a first oscillation abnormal portion 12 for generating an oscillation signal and outputting the oscillation signal and the oscillation signal delayed by -90 °. ), A first I synthesizer 13 for synthesizing a signal from the divider 11 and an oscillation signal from the first oscillator 12 and outputting a first I-IF signal, and the divider 11. A first Q synthesizer 14 for synthesizing the signal from the first oscillator 12 and the phase delayed oscillation signal from the first oscillator 12, and outputting a first Q-IF signal; A first filter 15 for passing a 1 I-IF signal in a preset band and a second filter 16 for passing a first Q-IF signal from the first Q synthesizer 14 in a preset band. And a second oscillation abnormality unit 17 for generating an oscillation signal and outputting the oscillation signal and the oscillation signal delayed by -90 °. A second I-synthesizer 18 for synthesizing the signal from the first filter 15 and the oscillation signal from the second oscillator 16 and outputting a second I-IF signal; A second Q synthesizer 19 for synthesizing the signal from 16 and the phase delayed oscillation signal from the second oscillator 16 and outputting a second Q-IF signal; and the second I and Q synthesizers 18. 19 subtracts the second I-IF and Q-IF signals from the second I-IF and Q-IF signals and the second I-IF and Q-IF signals from the second I and Q synthesizers 18 and 19. The subtractor 21 is included.

2 is a frequency spectrum diagram of a desired signal and an image signal.

In FIG. 2, the IF signal output from the first and second synthesizers includes an image signal in addition to the desired signal. Referring to FIG. 2, the IF signals are symmetrically positioned on both sides about the oscillation signal.

For example, the phase change for the case where the input RF signal is higher than the oscillation signal will be described with reference to FIGS. 3 and 4.

3 is a vector diagram showing phases of a desired signal and an image signal of an I pass.

Referring to FIG. 3, in the I-path corresponding to one signal path distributed by the divider 11 among the input signals, only the frequency is down-converted without a phase change and finally output.

4 is a vector diagram showing phases of a desired signal and an image signal of a Q pass.

Referring to FIG. 4, it can be seen that, in the Q pass corresponding to another signal path distributed by the divider 11 among the input signals, the phase is converted to -90 ° and then down-converted while being converted to + 90 °. .

That is, as shown in FIGS. 3 and 4. By adding the signal on the I pass and the signal on the Q pass, it can be seen that the image signal is removed and only the desired signal is output.

However, in the conventional image rejection mixer, the I and Q signals do not have an exact 90 ° phase difference due to various impedance differences on the line, so that a separate compensator is placed in the middle of the I and Q signals. To compensate for the phase of

Accordingly, in the conventional method, the method for phase modulation is performed by correcting the quadrature signal of the filter by using the variable resistance of the filter rod and the variable capacitor, or by adjusting the phase of the mixer or oscillator constituting the communication system. Since the magnitude and phase error of the quadrature signal must be corrected using the resistors, such a correction circuit must be added in an analog circuit, thereby increasing the power consumption and the complexity of the circuit.

The present invention has been proposed to solve the above problems, and an object thereof is to simply design a circuit for performing magnitude and phase compensation on an I signal and a Q signal without a separate compensation circuit using a GM cell. The present invention provides a GM-C filter having an IQ compensation function capable of correcting the magnitude and phase of an I signal and a Q signal without a separate magnitude and phase correction circuit such as a variable resistor.

In order to achieve the above object of the present invention, the GM-C filter of the present invention,

A first gain compensator implemented using a GM cell, amplifying an input I signal with a gain determined according to a gain control signal, and combining the amplified signal with the input signal to compensate for the magnitude of the I signal;

A first filter for passing the first I signal from the first gain compensator into a predetermined band;

A second gain compensator implemented using a GM cell, amplifying an input Q signal with a gain determined according to a gain control signal, and combining the amplified signal with the input signal to compensate for the magnitude of the Q signal;

A second filter for passing the first Q signal from the second gain compensator into a preset band;

Implemented using a GM cell, amplifies the second Q signal with a gain determined according to the phase control signal, synthesizes the amplified second Q signal and the first I signal from the first filter, and phases the I signal. A first phase compensator for compensating for and outputting a second first signal;

Implemented using a GM cell, amplifies the second I signal with a gain determined according to the phase control signal, synthesizes the amplified second I signal with the first Q signal from the second filter, and adjusts the phase of the Q signal. A second phase compensator configured to compensate and output a second Q signal;

A magnitude controller configured to output the gain control signal according to a magnitude difference between a second I signal of the first phase compensator and a second Q signal from the second phase compensator; And

A phase controller configured to output the phase control signal according to a phase difference between the second I signal of the first phase compensator and the second Q signal from the second phase compensator

Characterized in that it comprises a.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the drawings referred to in the present invention, components having substantially the same configuration and function will use the same reference numerals.

5 is a block diagram of a GM-C filter according to the present invention.

Referring to FIG. 5, the GM-C filter of the present invention is implemented using a GM cell, amplifies the input I signal I with a gain determined according to the gain control signal Va, and amplifies the input signal with the amplified signal. A first gain compensator 110 for synthesizing the signal to compensate for the magnitude of the I signal, and a first filter for passing the first I signal I1 from the first gain compensator 110 in a predetermined band. With 120. Second gain compensation for implementing using a GM cell, amplifying the input Q signal Q with a gain determined according to the gain control signal Va, and combining the amplified signal with the input signal to compensate for the magnitude of the Q signal. Phase 210, a second filter 220 for passing the first Q signal Q1 from the second gain compensator 210 in a predetermined band, and implemented using a GM cell, phase control The second Q signal Q2 is amplified with a gain determined according to the signal Vp, and the amplified second Q signal KQ2 and the first I signal I1 from the first filter 120 are synthesized. The first phase compensator 130 outputs the second first signal I2 by compensating the phase of the I signal and the GM cell, and the second I signal with a gain determined according to the phase control signal Vp. Amplifies (I2), synthesizes the amplified second I signal KI2 and the first Q signal Q1 from the second filter 220, and compensates the phase of the Q signal to compensate for the second Q signal Q2. ) The second phase compensator 230 and the magnitude of the second I signal I2 of the first phase compensator 130 and the second Q signal Q2 from the second phase compensator 230. The magnitude control unit 310 outputs the gain control signal Va according to the difference, the second I signal I2 of the first phase compensator 130 and the second phase compensator 230 from the second phase compensator 230. The phase controller 320 outputs the phase control signal Vp according to the phase difference from the 2 Q signal Q2.

6 is a configuration diagram of a first gain compensator of the present invention.

Referring to FIG. 6, the first gain compensator 110 may include a non-inverting input terminal connected to an input I signal I terminal, a grounded inverting terminal, and a preset gain GM11. A second GM cell GC11, an inverted input terminal connected to an input I signal I terminal, a grounded non-inverting terminal, and a second gain GM12 variable according to the gain control signal Va; Including a GM cell GC12, the gain control unit 111 which connects each output of the first GM cell GC11 and the second GM cell GC12 to one output stage and the input I signal I in advance The third GM cell GC13 amplified to the gain GM13 set in the above, and the fourth GM cell GC14 which synthesizes and outputs the output signal of the third GM cell GC13 and the output signal of the gain control unit 111. It consists of an input synthesizer 112, including.

7 is a configuration diagram of a second gain compensator of the present invention.

Referring to FIG. 7, the second gain compensator 210 has a non-inverting input terminal connected to an input Q signal Q terminal, a grounded inverting terminal, and a first gain GM21 that has a preset gain GM21. A second GM having a GM cell GC21, an inverting input connected to an input I signal Q, a grounded non-inverting terminal, and having a gain GM22 that is variable according to the gain control signal Va; Including the cell GC22, the gain control unit 211 which connects each output of the first GM cell GC21 and the second GM cell GC22 to one output stage and the input I signal Q in advance Fourth GM cell GC24 which synthesizes and outputs the third GM cell GC23 amplified to the set gain GM23 and the output signal of the third GM cell GC23 and the output signal of the gain control unit 211. It consists of an input synthesizer 212 comprising a.

8 is a configuration diagram of a first phase compensator of the present invention.

Referring to FIG. 8, the first phase compensator 130 has an inverting input terminal connected to an output terminal of the second phase compensator 230, has a grounded non-inverting terminal, and has a preset gain GM15. A fifth GM cell GC15 having an inverted input terminal connected to an output terminal of the second phase compensator 230, a grounded non-inverting terminal, and a variable variable according to the phase control signal Vp; A gain control unit 131 including a sixth GM cell GC16 having a GM16 and connecting the respective outputs of the fifth GM cell GC15 and the sixth GM cell GC16 to one output terminal; A seventh GM cell GC17 for amplifying the first I signal I1 from the first filter 120 to a preset gain GM17, an output signal of the seventh GM cell GC17, and the gain controller And an output synthesizing unit 132 including an eighth GM cell GC18 for synthesizing and outputting the output signal of 131.

9 is a configuration diagram of a second phase compensator of the present invention.

Referring to FIG. 9, the second phase compensator 230 has a non-inverting input terminal connected to an output terminal of the first phase compensator 130, has a grounded inverting terminal, and has a preset gain GM25. A fifth GM cell GC25 having an inverted input terminal connected to an output terminal of the first phase compensator 130, a grounded non-inverting terminal, and a variable variable according to the phase control signal Vp A gain control unit 231 including a sixth GM cell GC26 having a GM26 and connecting the respective outputs of the fifth GM cell GC25 and the sixth GM cell GC26 to one output terminal; A seventh GM cell GC27 for amplifying the first Q signal Q1 from the second filter 220 to a preset gain GM27, an output signal of the seventh GM cell GC27, and the gain agent; The output combiner 232 includes an eighth GM cell GC28 for synthesizing and outputting the output signal of the fisherman 231.

10 is a vector diagram for explaining phase compensation.

Hereinafter, the operation and effects of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 5, the first gain compensator 110 of the present invention is implemented using a GM cell, amplifies the input I signal I with a gain determined according to the gain control signal Va, and then amplifies the input I signal I. The magnitude of the I signal is compensated by combining the signal and the input signal. In addition, the first filter 120 of the present invention passes the first I signal I1 from the first gain compensator 110 in a predetermined band.

Next, the second gain compensator 210 of the present invention is implemented using a GM cell, amplifies the input Q signal Q with a gain determined according to the gain control signal Va, and then amplifies the input signal and the input signal. The signal is synthesized to compensate for the magnitude of the Q signal. The second filter 220 of the present invention passes the first Q signal Q1 from the second gain compensator 210 in a predetermined band.

In addition, the first phase compensator 130 of the present invention is implemented using a GM cell, amplifies the second Q signal Q2 with a gain determined according to the phase control signal Vp, and the amplified second Q. The signal KQ2 and the first I signal I1 from the first filter 120 are synthesized to compensate for the phase of the I signal to output the second first signal I2.

The second phase compensator 230 of the present invention is implemented using a GM cell, amplifies the second I signal I2 with a gain determined according to the phase control signal Vp, and the amplified second I The signal KI2 and the first Q signal Q1 from the second filter 220 are synthesized to compensate for the phase of the Q signal to output the second Q signal Q2.

Next, the magnitude controller 310 of the present invention measures the magnitude of the second I signal I2 of the first phase compensator 130 and the second Q signal Q2 from the second phase compensator 230. The gain control signal Va is output in accordance with the difference.

In addition, the phase control unit 320 of the present invention is a phase difference between the second I signal I2 of the first phase compensator 130 and the second Q signal Q2 from the second phase compensator 230. Accordingly, the phase control signal Vp is output.

Referring to FIGS. 5 and 6, the first gain compensator 110 will be described. In the gain controller 111 of the first gain compensator 110, the first GM cell GC11 may be set in advance. The gain GM11 has a gain, and the second GM cell GC12 has a gain GM12 that varies in accordance with the gain control signal Va.

Accordingly, the gain control unit 111 outputs an output KI including the gain GM12 that varies according to the gain control signal Va as shown in Equation 1 below.

In the input combining unit 112 of the first gain compensator 110, the third GM cell GC13 amplifies the input I signal I to a preset gain GM13, and the fourth GM cell. GC14 combines the output signal of the third GM cell GC13 and the output signal of the gain control unit 111 and outputs the synthesized signal.

Through this process, the first gain compensator 110 outputs the first I signal I1 as shown in Equation 2 below.

Referring to FIGS. 5 and 7, the second gain compensator 210 will be described. In the gain controller 211 of the second gain compensator 210, the first GM cell GC21 is previously set. The gain GM21 has a gain, and the second GM cell GC22 has a gain GM22 that varies in accordance with the gain control signal Va.

Accordingly, the gain control unit 211 outputs an output KQ including a gain GM22 that varies according to the gain control signal Va as shown in Equation 3 below.

In the input combiner 212 of the second gain compensator 210, the third GM cell GC23 amplifies the input I signal Q to a preset gain GM23, and the fourth GM cell. The GC24 combines the output signal of the third GM cell GC23 and the output signal of the gain control unit 211 and outputs the synthesized signal.

Through this process, the second gain compensator 210 outputs the first Q signal Q1 shown in Equation 4 below.

As described above, for example, when the magnitude Va of the I signal is greater than the magnitude VaQ of the Q signal, the gain control signal Va = VaI-VaQ becomes large, and the gain control signal Va ), The larger the GM12, the smaller the KI (GM11-GM12) and the larger the GM22, the larger the KQ (GM22-GM21).

Accordingly, the gain compensation of the present invention is made in a direction in which the magnitudes of the I and Q signals are the same.

Referring to FIGS. 5 and 8, the first phase compensator 130 will be described. In the gain controller 131 of the first phase compensator 130, the fifth GM cell GC15 is previously set. The sixth GM cell GC16 has a gain GM15, an inverting input terminal connected to an output terminal of the second phase compensator 230, a grounded non-inverting terminal, and is connected to the phase control signal Vp. It has a gain GM16 that varies accordingly.

Accordingly, the gain control unit 131 outputs an output KI1 including the gain GM16 that varies according to the phase control signal Vp as shown in Equation 5 below.

In the output synthesizing unit 132 of the first phase compensator 130, the seventh GM cell GC17 receives a predetermined gain (I) of the first I signal I1 from the first filter 120. Amplified by GM17, the eighth GM cell GC18 synthesizes the output signal of the seventh GM cell GC17 and the output signal of the gain control unit 131.

Through this process, the first phase compensator 130 outputs a second first signal I2 as shown in Equation 6 below.

Referring to FIGS. 5 and 9, the second phase compensator 230 will be described. In the gain controller 231 of the second phase compensator 230, the fifth GM cell GC25 is previously set. It has a gain GM25, and the sixth GM cell GC26 has a gain GM26 that is varied in accordance with the phase control signal Vp.

Accordingly, the gain control unit 231 outputs an output KQ1 including a gain GM26 that varies according to the phase control signal Vp as shown in Equation 7 below.

 In the output synthesizer 232 of the second phase compensator 230, the seventh GM cell GC27 receives the first Q signal Q1 from the second filter 220 in advance. Amplified by GM27, the eighth GM cell GC28 synthesizes the output signal of the seventh GM cell GC27 and the output signal of the gain control unit 231.

Through this process, the second phase compensator 230 outputs the second Q signal IQ as shown in Equation 8 below.

10A and 10B are vector diagrams for explaining phase compensation according to the present invention.

Referring to FIG. 10A, for example, when the difference between the phase VpI of the I signal and the phase VpQ of the Q signal is greater than 90 °, the phase control signal Vp = V (90 ° − (I phase −Q). Phase))) becomes smaller, and when the phase control signal Vp becomes smaller, GM16 becomes smaller and KI1 (-(GM15 + GM16)) becomes smaller in the negative direction, while GM26 becomes smaller, KQ1 (GM25- GM26) gets bigger. At this time, the phase of I changes small, and the phase of Q changes large in the same direction as the direction in which I changes.

Accordingly, the phase compensation of the present invention is made in a direction in which the phase difference between the I signal and the Q signal approaches 90 °.

Referring to FIG. 10B, for example, when the difference between the phase VpI of the I signal and the phase VpQ of the Q signal is less than 90 °, the phase control signal Vp = V (90 ° − (I phase −Q). Phase))) increases, and when the phase control signal Vp increases, GM16 increases, KI1 (-(GM15 + GM16)) increases in the negative direction, and GM26 increases, KQ1 (GM25-GM26) Becomes small. At this time, the phase of I changes greatly, and the phase of Q changes small in the same direction as the direction in which I changes.

Accordingly, the phase compensation of the present invention is made in a direction in which the phase difference between the I signal and the Q signal approaches 90 °.

According to the present invention as described above, in the GM-C filter applied to the image rejection mixer of the communication system, a circuit for performing magnitude and phase compensation for the I signal and the Q signal without a separate compensation circuit using a GM cell By simply designing, it is possible to correct the magnitude and phase of the I and Q signals without a separate magnitude and phase correction circuit such as a variable capacitor or a variable resistor.

Claims (5)

First gain compensation for implementing using a GM cell, amplifying the input I signal I with a gain determined according to the gain control signal Va, and combining the amplified signal with the input signal to compensate for the magnitude of the I signal. Unit 110; A first filter (120) for passing the first I signal (I1) from the first gain compensator (110) in a predetermined band; Second gain compensation for implementing using a GM cell, amplifying the input Q signal Q with a gain determined according to the gain control signal Va, and combining the amplified signal with the input signal to compensate for the magnitude of the Q signal. Part 210; A second filter 220 for passing the first Q signal Q1 from the second gain compensator 210 to a predetermined band; Implemented using a GM cell, amplifies the second Q signal Q2 with a gain determined according to the phase control signal Vp, and outputs the amplified second Q signal KQ2 from the first filter 120. A first phase compensator 130 synthesizing the first I signal I1 and compensating the phase of the I signal to output the second first signal I2; Implemented using a GM cell, amplifies the second I signal I2 with a gain determined according to the phase control signal Vp, and outputs the amplified second I signal KI2 from the second filter 220. A second phase compensator 230 for synthesizing the first Q signal Q1 and compensating the phase of the Q signal to output a second Q signal Q2; The gain control signal Va is output according to a magnitude difference between the second I signal I2 of the first phase compensator 130 and the second Q signal Q2 from the second phase compensator 230. A size control unit 310; And Outputting the phase control signal Vp according to a phase difference between the second I signal I2 of the first phase compensator 130 and the second Q signal Q2 from the second phase compensator 230. Phase control unit 320 GM-C filter having an IQ compensation function, characterized in that it comprises a. The method of claim 1, wherein the first gain compensator 110 A first GM cell GC11 having a non-inverting input terminal connected to the input I signal I terminal, a grounded inverting terminal, and having a preset gain GM11 connected to the input I signal I terminal. The first GM cell GC11 includes a second GM cell GC12 having an inverting input terminal, a grounded non-inverting terminal, and having a gain GM12 that varies according to the gain control signal Va. And a gain control unit 111 connecting each output of the second GM cell GC12 to one output terminal. And A third GM cell GC13 that amplifies the input I signal I to a preset gain GM13, an output signal of the third GM cell GC13, and an output signal of the gain control unit 111; An input combining unit 112 including a fourth GM cell GC14 to be output; GM-C filter having an IQ compensation function, characterized in that consisting of. The method of claim 1, wherein the second gain compensator 210 A first GM cell GC21 having a non-inverting input terminal connected to the input Q signal Q terminal, a grounded inverting terminal, and having a preset gain GM21 connected to the input I signal Q terminal. The first GM cell GC21 includes a second GM cell GC22 having an inverting input terminal, a grounded non-inverting terminal, and having a gain GM22 that varies according to the gain control signal Va. And a gain control unit 211 connecting each output of the second GM cell GC22 to one output terminal. And The third GM cell GC23 amplifies the input I signal Q to a preset gain GM23, the output signal of the third GM cell GC23 and the output signal of the gain control unit 211 are synthesized. An input synthesizing unit 212 including a fourth GM cell GC24 for outputting GM-C filter having an IQ compensation function, characterized in that consisting of. The method of claim 1, wherein the first phase compensator 130 A fifth GM cell GC15 having an inverting input terminal connected to an output terminal of the second phase compensator 230, a grounded non-inverting terminal, and having a preset gain GM15, and the second phase compensation; Including a sixth GM cell GC16 having an inverting input terminal connected to an output terminal of the unit 230, a grounded non-inverting terminal, and having a gain GM16 that is variable according to the phase control signal Vp. A gain control unit 131 connecting the outputs of the fifth GM cell GC15 and the sixth GM cell GC16 to one output terminal; And A seventh GM cell GC17 that amplifies the first I signal I1 from the first filter 120 to a preset gain GM17, and the output signal and the gain of the seventh GM cell GC17. An output synthesizing unit 132 including an eighth GM cell GC18 for synthesizing and outputting an output signal of the control unit 131. GM-C filter having an IQ compensation function, characterized in that consisting of. The method of claim 1, wherein the second phase compensator 230 A fifth GM cell GC25 having a non-inverting input terminal connected to an output terminal of the first phase compensator 130, a grounded inverting terminal, and having a preset gain GM25, and the first phase compensation Including a sixth GM cell GC26 having an inverting input terminal connected to an output terminal of the unit 130, a grounded non-inverting terminal, and having a gain GM26 that is variable according to the phase control signal Vp. A gain control unit 231 connecting the outputs of the fifth GM cell GC25 and the sixth GM cell GC26 to one output terminal; And A seventh GM cell GC27 for amplifying the first Q signal Q1 from the second filter 220 with a preset gain GM27, an output signal of the seventh GM cell GC27, and the gain An output synthesizing unit 232 including an eighth GM cell GC28 for synthesizing and outputting an output signal of the control unit 231. GM-C filter having an IQ compensation function, characterized in that consisting of.

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