CN114826205A - Vector modulation type active phase shifter - Google Patents

Abstract

The invention discloses a vector modulation type active phase shifter, which comprises a coupling network (100) for generating orthogonal signals, a first active amplitude control module (200) and a second active amplitude control module (300) which are formed by cascode transistor arrays for adjusting gains of in-phase signals and orthogonal signals, and a power synthesis and output matching network (400); the vector modulation type active phase shifter comprises a phase compensation network (500) which is arranged between a coupling network generating orthogonal signals and an active amplitude control module and is used for optimizing the phase bandwidth of the orthogonal signals and improving the phase shifting precision. The invention realizes the vector synthesis type active phase shifter with wide band, high precision and direct digital control in the 360-degree phase shift range.

Description

Vector modulation type active phase shifter

Technical Field

The invention relates to the technical field of electronic circuit design, in particular to the technical field of design of an active phase shifter applicable to a phased array system.

Background

In recent years, millimeter wave frequency bands have become a hot spot for developing 5G communication systems because of their wide frequency band and short wavelength, which can effectively solve many problems in high-speed broadband wireless communication. However, the high link loss of the millimeter wave band limits the communication distance. The phased array system can increase the communication distance by beamforming while reducing interference.

One of the core devices in a phased array system: the phase shifter, its phase shifting capability, directly determines the beam sweep range, sweep speed and phase shift accuracy. The accuracy of the phase shifter is improved, and the beam control error of the system can be effectively reduced. Therefore, in commercial application systems, high performance requirements such as high precision, low loss, low power consumption and high resolution are placed on the phase shifter.

The phase shifter is mainly realized by passive and active methods. In the patent "a high frequency vector modulation type passive phase shifter, CN 202010423709.8", a phase shifter with a passive structure is proposed, in which a coupler structure based on a transformer is adopted for generating quadrature signals, so that a large power loss is introduced, and the area of the quadrature coupler is large, which is not favorable for high integration. The vector modulation part adopts a transistor with a passive structure, cannot provide certain positive gain to make up for the loss of the orthogonal signal generation module and the power synthesis module, and is not beneficial to the transmission of radio frequency signals.

The multiple active phase shifters implement phase shift based on the principle of vector modulation, so the accuracy and range of vector magnitude control are important factors determining the performance of the active phase shifters. The structure of a common amplitude control module is as follows: a Gilbert structure amplifier based on tail current source control adjusts the gain of a transistor by controlling the magnitude of tail current, but a vertical stacking structure of three layers of tubes can cause the deterioration of linearity under the limitation of low power supply voltage, and the input and output impedance of the amplifier changes along with the change of direct current bias, so that the precision of vector synthesis is deteriorated, and the precision and the bandwidth of a phase shifter are limited. In the patent "a radio frequency active phase shifter structure, cn201910349347. x", the vector modulation circuit part adopts an amplifier with a common-gate structure, which improves linearity, stabilizes the input impedance of the module, and can provide a certain gain, but the ability of providing gain is limited, and the isolation of the input and output ends of the common-gate amplifier is poor, which is not favorable for improving impedance matching and phase shift accuracy. In addition, the noise coefficient of the common-gate amplifier is high, which deteriorates the noise performance of the phase shifter, and further affects the noise performance of the whole link.

Therefore, the phase shifter structure at the present stage has the problems of large loss, limited phase shift precision, large chip area, unfavorable high integration and the like, and is difficult to meet the higher requirements of future 5G communication, high-performance radar systems and phased array beam control on the integration level, the phase shift precision and the digit.

Disclosure of Invention

In view of the above-mentioned deficiencies of the prior art, the present invention provides an active phase shifter structure with a 360-degree phase adjustment range, a wide band, high accuracy, high gain, low amplitude error and low cost.

The invention adopts the following technical scheme for solving the technical problems:

a vector modulation type active phase shifter structure comprises a coupling network for generating orthogonal signals, an amplitude control module consisting of a transistor array for adjusting gains of in-phase and orthogonal signals, and a power synthesis and output matching network; a vector modulation type active phase shifter includes a phase compensation network for optimizing the phase and bandwidth of a quadrature signal between a coupling network generating the quadrature signal and an active amplitude control module.

In order to convert one path of input differential signals into two paths of orthogonal differential signals, the orthogonal coupling network can be any one of an all-pass filter based on an LC resonance network, a 90-degree coupler based on a transformer or an RC multi-phase filter. The all-pass filter based on the LC resonance network comprises a first inductor, a second inductor, a first capacitor, a second capacitor, a first resistor and a second resistor; the positive terminals of the first inductor and the first capacitor are connected together to serve as the input positive terminal of the coupling network, the positive terminals of the second inductor and the second capacitor are connected together to serve as the input negative terminal of the coupling network, the first resistor is bridged between the negative terminal of the second inductor and the negative terminal of the first capacitor, the second resistor is bridged between the negative terminal of the first inductor and the negative terminal of the second capacitor, and the positive terminal of the first resistor serves as the positive terminal V of the output I circuit of the coupling network _I,IN+ The negative end of the first resistor is used as the negative end V of the Q path of the output of the coupling network _Q,IN- The positive end of the second resistor is used as the positive end V of the Q circuit of the output of the coupling network _Q,IN+ The negative end of the second resistor is used as the negative end V of the output I path of the coupling network _I,IN- . The crossed resistance reduces the amplitude and phase errors of the output signals of the orthogonal coupling network, determines the input impedance of the orthogonal coupling network and completes input matching.

Furthermore, the resistance values of the first resistor and the second resistor are adjustable, and the first resistor and the second resistor are used for adjusting the signal phase of the coupling network generating the orthogonal signal, so that the high-precision orthogonal signal is realized; the first inductor and the second inductor have small coupling coefficient, and the broadband characteristic of the orthogonal output signal is improved.

Further, the phase compensation network of the present invention can extend the bandwidth of the quadrature signal coupling network and reduce the errors in the amplitude and phase of the quadrature signals. The phase compensation network comprises a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a third inductor and a fourth inductor. The third inductor is connected in series with the fifth capacitor, the fourth inductor is connected in series with the sixth capacitor, and negative ends of the third capacitor, the fourth capacitor, the fifth capacitor and the sixth capacitor are used as input of the active amplitude control module. The inductance connected in series in the compensation network offsets the capacitance of the input impedance of the post-stage circuit, compensates the phase and amplitude errors of the orthogonal signal of the orthogonal coupling network high frequency, and achieves the function of orthogonal signal calibration.

Furthermore, in order to realize amplitude control of two paths of orthogonal signals, a first active amplitude control module and a second active amplitude control module of the invention are respectively composed of a common source transistor and a plurality of parallel-connected common-gate transistor array units, the common source transistor is composed of a first transistor and a second transistor to form a differential pair, the common-gate transistor array units are composed of a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a first buffer and a second buffer, wherein the drain electrode of the first transistor is connected with the source electrodes of the third transistor and the fourth transistor, the drain electrode of the second transistor is connected with the source electrodes of the fifth transistor and the sixth transistor, and the drain electrode of the third transistor and the drain electrode of the sixth transistor are connected as the output positive VI end of the I-path differential signal _OUT+ The drain electrode of the fourth transistor is connected with the drain electrode of the fifth transistor to be used as the output VI of the negative end of the I-path differential signal _OUT- Gates of the third transistor and the fifth transistor are connected to an output terminal of the first buffer, and gates of the fourth transistor and the sixth transistor are connected to an output terminal of the second buffer. And two groups of digital control instructions are respectively connected to the input ends of the first buffer and the second buffer of each array unit to control the on-off state of a transistor connected with the output end of the buffer so as to realize the adjustment of the amplitude of the output current. Wherein there is no inverse logical relationship between the two sets of digital control instructions. The logic of the two groups of digital control instructions ensures that the total size of the common-gate tube in an open state is kept constant every time, theoretically, phase shift deviation caused by input and output impedance changes of the transistor array under different gain gears is completely solved, and therefore the constant output impedance, and good flatness and precision of the phase of an output signal can be ensured under any phase state; on the other hand, the difference of the sizes of the common-gate tubes in the on state controlled by two groups of digital control instructions determines the amplitude of the output signal, thereby realizing wide rangeGain adjustment of (1).

Further, the first transistor and the second transistor in the common source transistor are the same in size; and the sizes of the third transistor, the fourth transistor, the fifth transistor and the sixth transistor in the common-gate transistor array unit are the same.

Further, the total size of the common-gate transistors in each unit of the plurality of parallel common-gate transistor array units is increased by a proportionality coefficient N, and the proportionality coefficient N is any positive real number.

Furthermore, the power synthesis and output matching network comprises a power synthesizer and a synthesized output matching network, wherein the power synthesizer consists of a first transmission line, a second transmission line, a third transmission line and a fourth transmission line, and the power synthesizer outputs a positive terminal VI of an I path differential signal output by the orthogonal coupling network _OUT+ Positive terminal VQ of differential signal with Q path _OUT+ Composite signal V _C,OUT+ Negative terminal VI of path I differential signal _OUT- Negative terminal VQ of Q-path differential signal _OUT- Synthesis of V _C,OUT- The vector addition of I, Q two orthogonal differential signal currents is completed, and one output differential signal after synthesis is used as the input of the output matching network. The output matching network consists of a first transformer, a seventh capacitor and an eighth capacitor with a coupling coefficient k, wherein the coupling coefficient k determines the bandwidth of the matching network, a center tap of a primary coil of the first transformer is connected with a power supply, and differential outputs of the matching network are output signals VOUT + and VOUT-of the phase shifter.

The novel phase shifter structure designed by the invention improves the phase shift precision, optimizes the phase shift flatness, reduces the amplitude and phase errors, widens the working bandwidth, realizes the generation and synthesis of broadband orthogonal signals and has good linearity. The phase shifter structure can realize a vector synthesis type active phase shifter with broadband, high precision and direct digital control over a 360-degree phase shift range.

Compared with the prior art, the invention has the following technical effects:

1. the active amplitude control module adopts a cascode structure and adopts a cross-coupled connection mode at the output end of the transistor, so that the isolation between the input port and the output port of the active amplitude control module is high, the module gain is high, the input impedance and the output impedance are constant under any phase shift gear, and further, the phase flatness and the precision of an output signal are ensured to be high, and the amplitude error is small;

2. the invention adopts a plurality of parallel common-gate transistor arrays to realize amplitude modulation, on one hand, direct digital control is adopted, thus greatly reducing response delay, and on the other hand, the sensitivity of phase-shifting performance to process, power supply and temperature is greatly weakened;

3. the vector modulation phase shifter with the active structure can provide positive gain and is beneficial to being used in radio frequency and medium frequency signal paths;

4. the vector modulation type active phase shifter can be widely applied to a phased array system, a radar system or a radio frequency receiver and a transmitter, realizes high-precision control on signal phases, and has novelty and universality.

Drawings

Fig. 1 is a block diagram showing a structure of a vector modulation type active phase shifter according to the present invention;

fig. 2 is a schematic circuit diagram of a vector modulation type active phase shifter according to the present invention;

fig. 3 is a schematic circuit diagram of a vector modulation type active phase shifter according to the present invention;

FIG. 4 shows the phase shifting performance of the phase shifter of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

Example 1:

as shown in fig. 1, the vector modulation type active phase shifter structure provided by the present invention includes a coupling network 100 for generating quadrature signals, active amplitude control modules 200 and 300, a power combining and output matching network 400, and a phase compensation network 500.

As shown in fig. 2, the coupling network 100 for generating quadrature signals in the present invention is composed of inductors 101 and 102, capacitors 103 and 104, and resistors 105 and 106; the positive terminals of the inductor 101 and the capacitor 103 are connected together to serve as an input positive terminal of the coupling network, the positive terminals of the inductor 102 and the capacitor 104 are connected together to serve as an input negative terminal of the coupling network, the resistor 105 is connected across the negative terminal of the inductor 102 and the negative terminal of the capacitor 103, the resistor 106 is connected across the negative terminal of the inductor 101 and the negative terminal of the capacitor 104, and the positive terminal of the resistor 105 serves as a positive terminal V of an output I-path of the coupling network _I,IN+ The negative terminal of the resistor 105 is used as the negative terminal V of the output Q circuit of the coupling network _Q,IN- The positive terminal of the resistor 106 is used as the positive terminal V of the Q-path of the output of the coupling network _Q,IN+ The negative terminal of the resistor 106 is used as the negative terminal V of the output I of the coupling network _I,IN- . Wherein, the I path and the Q path are used for indicating the orthogonal relation of the signal phase. The coupling coefficient of the inductors 101, 102 in the coupling network is low. The resistors 105 and 106 reduce the Q value of the resonant cavity, and improve the real resistance of the network input impedance, so that the resistance value of the resistors is adjustable, the adjustment of the resistors realizes the control of the phase of the orthogonal signal, and the input impedance matching is completed.

As shown in fig. 2, the first active amplitude control module 200 and the second active amplitude control module 300 in the present invention have the same structure, are modules for realizing amplitude control of in-phase and quadrature signals, and both adopt a cascode structure, wherein a common gate stage is composed of a plurality of parallel common gate transistor array units, the size of the common gate transistor in each unit is the same, the total size of the common gate transistors in different units is increased by a proportionality coefficient N times, and the proportionality coefficient N is any positive real number. It should be noted that, the number of the transistor array units is 6, and the scaling factor N is 2, which can meet the requirement of phase shift precision of 5.625 °, and if higher precision is required, more transistor array units can be connected in parallel or the value of the scaling factor N can be modified. Wherein, the common source transistor is composed of differential pair transistors 201 and 202, the common gate transistor array unit is composed of transistors 203, 204, 205 and 206 and buffers 207 and 208, the drain of the transistor 201 is connected with the sources of the transistors 203 and 204, the drain of the transistor 202 is connected with the sources of the transistors 205 and 206, the drain of the transistor 203 and the drain of the transistor 206 are connected as an I-pathOutput VI of positive terminal of differential signal _OUT+ The drain of the transistor 204 and the drain of the transistor 205 are connected to the output VI which is the negative terminal of the I-path differential signal _OUT- The gates of the transistors 203 and 205 are connected to the output end of the first buffer, the gates of the transistors 204 and 206 are connected to the output end of the second buffer, and two sets of digital control commands are respectively connected to the input ends of the first and second buffers to directly control the on or off of the common-gate transistors correspondingly connected to the buffers, so that high-speed digital signal control amplitude is realized.

As shown in fig. 2, the power combining and output matching network 400 in the present invention includes a power combiner and a combined output matching network. The power combiner realizes the vector addition of I, Q paths of currents and the power combination of two paths of orthogonal differential signals. The power combiner consists of transmission lines 401, 402, 403 and 404, and the transmission lines 401 and 403 are used for connecting the positive terminal VI of the I-path differential signal _OUT+ Positive terminal VQ of differential signal with Q path _OUT+ Power combined signal V _C,OUT+ The transmission lines 402 and 404 couple the negative terminal VI of the I-path differential signal _OUT- Negative terminal VQ of Q-path differential signal _OUT- Power synthesis V _C,OUT- And the synthesized differential signal is used as the input of the output matching network. The output matching network is composed of a transformer 406 with a coupling coefficient k and capacitors 405 and 407, wherein the coupling coefficient k determines the bandwidth of the matching network, a center tap of a primary coil of the transformer 406 is connected with a power supply, the capacitors 405 and 407 can be any one of on-chip capacitors or on-chip adjustable capacitors, and differential outputs of the matching network are output signals VOUT + and VOUT-of the phase shifter.

As shown in fig. 3, the phase compensation network 500 in the present invention can extend the bandwidth of the quadrature signal coupling network 100 and reduce the errors of the quadrature signal amplitude and phase. Phase compensation network 500 includes capacitors 501, 502, 504, 506 and inductors 503, 505. The inductor 503 is connected in series with the capacitor 504, the inductor 505 is connected in series with the capacitor 506, the capacitors 501 and 506 have the same size, the capacitors 504 and 506 have the same size, and the inductors 503 and 505 have the same size. The inductors 503 and 505 neutralize the input capacitance of the post-stage circuit, thereby compensating the high-frequency performance of the quadrature signal coupling network, realizing the correction of the amplitude and phase error of the quadrature signal, and improving the accuracy of the phase shifter.

Fig. 4 shows the phase shift performance of the phase shifter of the present invention in the normalized frequency range, which can achieve phase shift in the 360 ° range with at least 6-bit precision, and no phase states overlap.

The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.

Claims (10)

1. A vector modulation type active phase shifter, characterized in that, the vector modulation type active phase shifter comprises a coupling network (100) for generating orthogonal signals, a first active amplitude control module (200) and a second active amplitude control module (300) composed of transistor arrays for adjusting the gains of in-phase and orthogonal signals, a power synthesis and output matching network (400); the vector modulation type active phase shifter also comprises a phase compensation network (500) which is positioned between the coupling network generating the orthogonal signal and the active amplitude control module and is used for optimizing the phase bandwidth of the orthogonal signal and improving the phase shifting precision.

2. A vector modulation type active phase shifter according to claim 1, characterized in that: the coupling network (100) generating the quadrature signals is any one of an all-pass filter based on an LC resonance network, a 90 DEG transformer-based coupler or an R-C polyphase filter; the coupling network (100) for generating the orthogonal signal can also adjust the phase of the signal, so that the phase shift precision of the phase shifter is improved; the coupling network for generating the orthogonal signals converts one path of differential input signals VIN + and VIN-into two paths of mutually orthogonal differential signals V _I,IN+ ，V _I,IN -and V _Q,IN+ ,V _Q,IN- 。

3. A vector modulation type active phase shifter according to claim 1, characterized in that: the coupling network (100) generating the quadrature signals is based on LC harmonicsAn all-pass filter of the vibration network; the coupling network for generating the quadrature signals is composed of a first inductor (101), a second inductor (102), a first capacitor (103), a second capacitor (104), a first resistor (105) and a second resistor (106); the first resistor (105) and the second resistor (106) are realized by polysilicon resistors or adjustable resistors; the positive ends of a first inductor (101) and a first capacitor (103) are connected together to serve as the input positive end of a coupling network, the positive ends of a second inductor (102) and a second capacitor (104) are connected together to serve as the input negative end of the coupling network, a first resistor (105) is connected across the negative end of the second inductor (102) and the negative end of the first capacitor (103), a second resistor (106) is connected across the negative end of the first inductor (101) and the negative end of the second capacitor (104), and the positive end of the first resistor (105) serves as the positive end V (V) of the coupling network output I _I,IN+ The negative end of the first resistor (105) is used as the negative end V of the Q circuit of the output of the coupling network _Q,IN- The positive end of the second resistor (106) is used as the positive end V of the Q circuit of the output of the coupling network _Q,IN+ The negative end of the second resistor (106) is used as the negative end V of the output I path of the coupling network _I,IN- And the first resistor (105) and the second resistor (106) are adjustable in resistance and used for adjusting the signal phase of the coupling network generating the quadrature signals.

4. A vector modulation type active phase shifter according to claim 1, characterized in that: the phase compensation network (500) can extend the bandwidth of the coupling network (100) that generates the quadrature signals and reduce errors in the quadrature signal amplitude and phase, the phase compensation network (500) comprises a third capacitor (501), a fourth capacitor (502), a fifth capacitor (504), a sixth capacitor (506), a third inductor (503) and a fourth inductor (505), wherein the third inductor (503) is connected with the fifth capacitor (504) in series, the fourth inductor (505) is connected with the sixth capacitor (506) in series, the fifth capacitor (504) and the sixth capacitor (506) are the same in size, the third capacitor (501) and the fourth capacitor (502) are the same in size, the third inductor (503) and the fourth inductor (505) are the same in size, and negative terminals of the third capacitor (501), the fourth capacitor (502), the fifth capacitor (504) and the sixth capacitor (506) are used as four-way inputs of the active amplitude control module.

5. A vector modulation type active phase shifter according to claim 1, characterized in that: the first active amplitude control module (200) is composed of a common source transistor and a plurality of parallel common gate transistor array units.

6. The vector modulation type active phase shifter according to claim 5, characterized in that: the common-source transistor comprises a first transistor (201) and a second transistor (202) which form a differential pair, the common-gate transistor array unit comprises a third transistor (203), a fourth transistor (204), a fifth transistor (205), a sixth transistor (206), a first buffer (207) and a second buffer (208), the drain of the first transistor (201) is connected with the sources of the third transistor (203) and the fourth transistor (204), the drain of the second transistor (202) is connected with the sources of the fifth transistor (205) and the sixth transistor (206), the drain of the third transistor (203) and the drain of the sixth transistor (206) are connected with each other to serve as an output VI positive end of the I-path differential signal _OUT+ The drain electrode of the fourth transistor (204) and the drain electrode of the fifth transistor (205) are connected with an output VI which is used as the negative end of the I-path differential signal _OUT- The gates of the third transistor (203) and the fifth transistor (205) are connected to the output of the first buffer, and the gates of the fourth transistor (204) and the sixth transistor (206) are connected to the output of the second buffer.

7. The vector modulation type active phase shifter according to claim 6, characterized in that: the sizes of a first transistor (201) and a second transistor (202) in the common-source transistor are the same, and the sizes of a third transistor (203), a fourth transistor (204), a fifth transistor (205) and a sixth transistor (206) in the common-gate transistor array unit are the same.

8. The vector modulation type active phase shifter according to claim 6, characterized in that: the total size of the common gate transistor in each unit is increased by N times of a proportionality coefficient, and the proportionality coefficient N is any positive real number.

9. A vector modulation type active phase shifter according to claim 1, characterized in that: the second active amplitude control module (300) and the first active amplitude control module (200) have the same structure.

10. A vector modulation type active phase shifter according to claim 1, characterized in that: the power synthesis and output matching network (400) comprises a power synthesizer and a synthesized output matching network, wherein the power synthesizer consists of a first transmission line (401), a second transmission line (402), a third transmission line (403) and a fourth transmission line (404), and the power synthesizer is used for converting the positive end VI of the I path differential signal into the negative end VI of the I path differential signal _OUT+ Positive end VQ of Q-path differential signal _OUT+ Power combined signal V _C,OUT+ Negative terminal VI of path I differential signal _OUT- Negative terminal VQ of Q-path differential signal _OUT- Power synthesis V _C,OUT- The synthesized differential signal is used as the input of an output matching network; the output matching network consists of a first transformer (406), a seventh capacitor (405) and an eighth capacitor (407) with a coupling coefficient k, wherein the coupling coefficient k determines the bandwidth of the matching network, a center tap of a main-stage coil of the first transformer (406) is connected with a power supply, and differential outputs of the matching network are output signals VOUT + and VOUT-of the phase shifter.

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