A vector modulation type active phase shifter

Abstract

This invention discloses a vector modulation active phase shifter, comprising a coupling network (100) for generating quadrature signals, a first active amplitude control module (200) and a second active amplitude control module (300) composed of a common-source cascode transistor array for adjusting the gain of in-phase and quadrature signals, and a power combining and output matching network (400). The vector modulation active phase shifter includes a phase compensation network (500) located between the coupling network for generating quadrature signals and the active amplitude control module, used to optimize the phase bandwidth of the quadrature signals and improve phase shift accuracy. This invention realizes a wideband, high-precision, directly digitally controlled vector combining active phase shifter with a 360° phase shift range.

Description

Technical Field

[0001] This invention relates to the technical field of electronic circuit design, and more particularly to the technical field of active phase shifter design applicable to phased array systems. Background Technology

[0002] In recent years, the millimeter-wave band, with its wide bandwidth and short wavelength, has become a hot topic in 5G communication system development due to its ability to effectively solve many problems in high-speed broadband wireless communication. However, the high link loss in the millimeter-wave band limits communication distance. Phased array systems can increase communication distance and reduce interference through beamforming.

[0003] One of the core components in a phased array system is the phase shifter, whose phase-shifting capability directly determines the beam scanning range, scanning speed, and phase-shifting accuracy. Improving the accuracy of the phase shifter can effectively reduce the beam control error of the system. Therefore, in commercial applications, phase shifters are required to meet high-performance requirements such as high precision, low loss, low power consumption, and high resolution.

[0004] Phase shifters are mainly implemented in two ways: passive and active. The patent "A High-Frequency Vector Modulation Passive Phase Shifter, CN202010423709.8" proposes a passive phase shifter structure. However, the generation of quadrature signals uses a transformer-based coupler structure, which introduces significant power loss. Furthermore, the large area of ​​the quadrature coupler hinders high integration. The vector modulation section uses passive transistors, which cannot provide sufficient positive gain to compensate for the losses in the quadrature signal generation and power combining modules, thus negatively impacting RF signal transmission.

[0005] Active phase shifters are mostly based on the principle of vector modulation to achieve phase shifting. Therefore, the accuracy and range of vector amplitude control are important factors determining the performance of active phase shifters. Common amplitude control module structures include Gilbert structure amplifiers based on tail current source control. This structure adjusts the transistor gain by controlling the tail current magnitude. However, the vertical stacking structure of three transistors leads to linearity degradation under low supply voltage limitations, and the input and output impedances of the amplifier change with the DC current bias, thus deteriorating the accuracy of vector synthesis and limiting the accuracy and bandwidth of the phase shifter. In the patent "A Radio Frequency Active Phase Shifter Structure, CN201910349347.X", the vector modulation circuit uses a common-gate amplifier. Although this structure improves linearity, stabilizes the module's input impedance, and can provide some gain, the gain provision capability is limited, and the poor isolation between the input and output terminals of the common-gate amplifier is detrimental to impedance matching and phase shift accuracy. In addition, the common-gate amplifier has a high noise figure, which deteriorates the noise performance of the phase shifter and thus affects the overall noise performance of the link.

[0006] Therefore, the current phase shifter structure has problems such as high loss, limited phase shift accuracy, and large chip area which is not conducive to high integration, making it difficult to meet the higher requirements of future 5G communication, high-performance radar systems, and phased array beam control for integration, phase shift accuracy, and number of bits. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides an active phase shifter structure with a 360-degree phase adjustment range, wide bandwidth, high precision, high gain, low amplitude error, and low cost.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A vector modulation active phase shifter structure includes a coupling network for generating quadrature signals, an amplitude control module consisting of a transistor array for adjusting the gain of in-phase and quadrature signals, a power combining and output matching network; a vector modulation active phase shifter includes a phase compensation network for optimizing the phase and bandwidth of the quadrature signals, located between the coupling network for generating quadrature signals and the active amplitude control module.

[0010] To convert one input differential signal into two orthogonal differential signals, the orthogonal coupling network of this invention can be any one of an all-pass filter based on an LC resonant network, a 90° coupler based on a transformer, or an RC multiphase filter. The all-pass filter based on an LC resonant network includes 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 as the positive input terminal of the coupling network, and the positive terminals of the second inductor and the second capacitor are connected together as the negative input terminal of the coupling network. The first resistor is connected across the negative terminals of the second inductor and the first capacitor, and the second resistor is connected across the negative terminals of the first inductor and the second capacitor. The positive terminal of the first resistor serves as the positive terminal V of the output I path of the coupling network. I,IN+ The negative terminal of the first resistor serves as the negative terminal V of the output Q path of the coupling network. Q,IN- The positive terminal of the second resistor serves as the positive terminal V of the output Q path of the coupling network. Q,IN+ The negative terminal of the second resistor serves as the negative terminal V of the output I path of the coupling network. I,IN- The bridging resistor reduces the amplitude and phase error of the output signal of the quadrature coupling network, and at the same time determines the input impedance of the quadrature coupling network, thus completing the input matching.

[0011] Furthermore, the resistance values ​​of the first and second resistors of the present invention are adjustable, which is used to adjust the signal phase of the coupling network that generates orthogonal signals, thereby achieving high-precision orthogonal signals; the first and second inductors of the present invention have small coupling coefficients, which improves the broadband characteristics of the orthogonal output signal.

[0012] Furthermore, the phase compensation network of this invention can extend the bandwidth of the quadrature signal coupling network and reduce the amplitude and phase errors of the quadrature signals. The phase compensation network includes a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a third inductor, and a fourth inductor. The third and fifth inductors are connected in series, and the fourth and sixth inductors are also connected in series. The negative terminals of the third, fourth, fifth, and sixth capacitors serve as the input to the active amplitude control module. The series-connected inductors in the compensation network cancel out the capacitiveness of the input impedance of the subsequent circuit, compensating for the high-frequency phase and amplitude errors of the quadrature signals in the quadrature coupling network, thus achieving the function of quadrature signal calibration.

[0013] Furthermore, to achieve amplitude control of the two orthogonal signals, both the first and second active amplitude control modules of this invention are composed of common-source transistors and multiple parallel common-gate transistor array units. The common-source transistors consist of a differential pair formed by a first transistor and a second transistor. The common-gate transistor array unit consists of a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a first buffer, and a second buffer. The drain of the first transistor is connected to the source of the third and fourth transistors, and the drain of the second transistor is connected to the source of the fifth and sixth transistors. The drains of the third and sixth transistors are connected together as the output VI of the positive terminal of the I-channel differential signal. OUT+ The drains of the fourth and fifth transistors are connected together to form the output VI of the negative terminal of the I-channel differential signal. OUT- The gates of the third and fifth transistors are connected to the output of the first buffer, and the gates of the fourth and sixth transistors are connected to the output of the second buffer. Two sets of digital control instructions are connected to the inputs of the first and second buffers of each array unit, respectively, controlling the on / off state of the transistors connected to the outputs of the buffers, thereby adjusting the output current amplitude. There is no inverse logic relationship between the two sets of digital control instructions. The logic of the two sets of digital control instructions ensures, on the one hand, that the total size of the common-gate transistor remains constant in the on state, theoretically completely solving the phase shift deviation introduced by changes in the input and output impedance of the transistor array under different gain levels, thus ensuring constant output impedance and good phase flatness and accuracy of the output signal in any phase state; on the other hand, the difference in the size of the common-gate transistor in the on state controlled by the two sets of digital control instructions determines the amplitude of the output signal, thereby achieving a wide range of gain adjustment.

[0014] Furthermore, the first and second transistors in the common-source transistor are of the same size; the third, fourth, fifth, and sixth transistors in the common-gate transistor array unit are of the same size.

[0015] Furthermore, in the plurality of parallel common-gate transistor array units, the total size of the common gate transistor in each unit increases by a factor of N, where the factor of N is any positive real number.

[0016] Furthermore, the power combining and output matching network of the present invention includes a power combiner and a combined output matching network. The power combiner consists of a first transmission line, a second transmission line, a third transmission line, and a fourth transmission line. The power combiner converts the positive terminal VI of the I-channel differential signal output by the quadrature coupling network... OUT+ The positive terminal VQ of the Q-channel differential signal OUT+ Synthetic signal V C,OUT+ The negative terminal VI of the I-channel differential signal OUT- The negative terminal VQ of the Q-channel differential signal OUT- Synthetic V C,OUT- The vector summation of the orthogonal differential signal currents I and Q was completed, and the resulting differential signal was used as the input to the output matching network. The output matching network consists of a first transformer, a seventh capacitor, and an eighth capacitor with a coupling coefficient of k. The coupling coefficient k determines the bandwidth of the matching network. The center tap of the main winding of the first transformer is connected to the power supply. The differential outputs of the matching network are the output signals VOUT+ and VOUT- of the phase shifter.

[0017] The novel phase shifter structure designed in this invention improves phase shift accuracy, optimizes phase shift flatness, reduces amplitude and phase errors, and widens the operating bandwidth, enabling the generation and synthesis of broadband orthogonal signals with good linearity. This phase shifter structure can realize a broadband, high-precision, direct digitally controlled vector synthesis active phase shifter with a 360° phase shift range.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] 1. The active amplitude control module of the present invention adopts a common source and common gate structure and uses a cross-coupled connection method at the transistor output terminal. Therefore, the isolation between the input port and the output port of the active amplitude control module is high, the module gain is high, and the input and output impedances are constant at any phase shift level, thereby ensuring the phase flatness and accuracy of the output signal and the small amplitude error.

[0020] 2. This invention uses multiple parallel common gate transistor arrays to achieve amplitude modulation. On the one hand, it adopts direct digital control, which greatly reduces the response delay. On the other hand, it greatly reduces the sensitivity of phase shift performance to process, power supply and temperature.

[0021] 3. The active structure vector modulation phase shifter of the present invention can provide positive gain, which is beneficial for use in radio frequency and intermediate frequency signal paths;

[0022] 4. The present invention provides a vector modulation type active phase shifter, which can be widely used in phased array systems, radar systems, or radio frequency receivers and transmitters to achieve high-precision control of signal phase, and has novelty and versatility. Attached Figure Description

[0023] Figure 1 This is a structural block diagram of a vector modulation active phase shifter according to the present invention;

[0024] Figure 2 This is a schematic diagram of the circuit structure of a vector modulation active phase shifter according to the present invention;

[0025] Figure 3 This is a schematic diagram of the circuit structure of a vector modulation active phase shifter according to the present invention;

[0026] Figure 4 These are the test results of the phase shifting performance of the phase shifter of this invention. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] Example 1:

[0029] like Figure 1 As shown, the vector modulation 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.

[0030] like Figure 2 As shown, the coupling network 100 for generating orthogonal signals in this invention consists of inductors 101 and 102, capacitors 103 and 104, and resistors 105 and 106. The positive terminals of inductor 101 and capacitor 103 are connected together as the positive input terminal of the coupling network, the positive terminals of inductor 102 and capacitor 104 are connected together as the negative input terminal of the coupling network, resistor 105 is connected across the negative terminal of inductor 102 and capacitor 103, and resistor 106 is connected across the negative terminal of inductor 101 and capacitor 104. The positive terminal of resistor 105 serves as the positive terminal V of the output I path of the coupling network. I,IN+ The negative terminal of resistor 105 serves as the negative terminal V of the output Q path of the coupling network. Q,IN- The positive terminal of resistor 106 serves as the positive terminal V of the output Q path of the coupling network. Q,IN+ The negative terminal of resistor 106 serves as the negative terminal V of the output I path of the coupling network. I,IN-In this context, I-path and Q-path refer to the orthogonality of the signal phases. The coupling coefficients of inductors 101 and 102 in the coupling network are very low. Resistors 105 and 106 reduce the Q value of the resonant cavity and increase the real resistance of the network input impedance. On the one hand, the resistor values ​​are adjustable, allowing control of the orthogonal signal phases; on the other hand, they achieve input impedance matching.

[0031] like Figure 2 As shown, the first active amplitude control module 200 and the second active amplitude control module 300 in this invention have the same structure. They are modules for controlling the amplitude of both in-phase and quadrature signals. Both adopt a common-source common-gate cascaded structure, where the common-gate stage consists of multiple parallel common-gate transistor array units. The size of the common-gate transistor in each unit is the same, and the total size of the common-gate transistors in different units increases by a proportional factor N, where the proportional factor N is any positive real number. It should be noted that here, the number of transistor array units is 6, and the proportional factor N of 2 is sufficient to meet the phase shift accuracy requirement of 5.625°. If higher accuracy is required, more transistor array units can be connected in parallel or the value of the proportional factor N can be modified. The common-source transistor consists of differential pairs 201 and 202, and the common-gate transistor array unit consists of transistors 203, 204, 205, 206 and buffers 207 and 208. The drain of transistor 201 is connected to the source of transistors 203 and 204, the drain of transistor 202 is connected to the source of transistors 205 and 206, and the drains of transistors 203 and 206 are connected together as the output VI of the positive terminal of the I-channel differential signal. OUT+ The drains of transistor 204 and transistor 205 are connected together to form the output VI of the negative terminal of the I-channel differential signal. OUT- The gates of transistors 203 and 205 are connected to the output of the first buffer, and the gates of transistors 204 and 206 are connected to the output of the second buffer. Two sets of digital control commands are connected to the inputs of the first and second buffers respectively, directly controlling the conduction or cutoff of the common-gate transistors connected to the buffers, thereby realizing high-speed digital signal control amplitude.

[0032] like Figure 2 As shown, the power combining and output matching network 400 in this invention includes a power combiner and a combined output matching network. The power combiner realizes the vector addition of the I and Q currents and the power combining of two orthogonal differential signals. The power combiner consists of transmission lines 401, 402, 403, and 404. Transmission lines 401 and 403 connect the positive terminal VI of the I differential signal. OUT+ The positive terminal VQ of the Q-channel differential signal OUT+ Power synthesized signal V C,OUT+ Transmission lines 402 and 404 connect the negative terminal VI of the I-channel differential signal. OUT- The negative terminal VQ of the Q-channel differential signal OUT- Power combining VC,OUT- The synthesized differential signal will serve as the input to the output matching network. The output matching network consists of a transformer 406 with a coupling coefficient of k and capacitors 405 and 407. The coupling coefficient k determines the bandwidth of the matching network. The center tap of the main winding of transformer 406 is connected to the power supply. Capacitors 405 and 407 can be either on-chip capacitors or on-chip adjustable capacitors. The differential output of the matching network is the output signals VOUT+ and VOUT- of the phase shifter.

[0033] like Figure 3 As shown, the phase compensation network 500 in this invention can extend the bandwidth of the quadrature signal coupling network 100 and reduce the amplitude and phase errors of the quadrature signals. The phase compensation network 500 includes capacitors 501, 502, 504, and 506, and inductors 503 and 505. Inductor 503 and capacitor 504 are connected in series, and inductor 505 and capacitor 506 are connected in series. Capacitors 501 and 506 are of the same size, as are capacitors 504 and 506, and inductors 503 and 505. Inductors 503 and 505 neutralize the input capacitance of the subsequent circuit, thereby compensating for the high-frequency performance of the quadrature signal coupling network, correcting the amplitude and phase errors of the quadrature signals, and improving the accuracy of the phase shifter.

[0034] Figure 4 The test results of the phase shifter of the present invention are shown in the normalized frequency range. The phase shifter can achieve phase shift of at least 6 bits with a range of 360° and no phase state overlap.

[0035] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A vector modulation type active phase shifter, characterized by, The vector modulation type active phase shifter comprises a coupling network (100) for generating quadrature signals, a first active amplitude control module (200) and a second active amplitude control module (300) composed of a transistor array for adjusting the gain of in-phase and quadrature signals, and a power synthesis and output matching network (400). The first active amplitude control module (200) is composed of a common source transistor and a plurality of parallel common gate transistor array units; the common source transistor is composed of a differential pair of a first transistor (201) and a second transistor (202), the common gate transistor array unit is composed of 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 electrode of the first transistor (201) is connected to the source electrode of the third transistor (203) and the fourth transistor (204), the drain electrode of the second transistor (202) is connected to the source electrode of the fifth transistor (205) and the sixth transistor (206), the drain electrode of the third transistor (203) and the drain electrode of the sixth transistor (206) are connected to output VI OUT+ as the positive end of the I-channel differential signal, the drain electrode of the fourth transistor (204) and the drain electrode of the fifth transistor (205) are connected to output VI OUT- as the negative end of the I-channel differential signal, the gate electrode of the third transistor (203) and the gate electrode of the fifth transistor (205) are connected to the output end of the first buffer, and the gate electrode of the fourth transistor (204) and the gate electrode of the sixth transistor (206) are connected to the output end of the second buffer. The vector modulation type active phase shifter further comprises a phase compensation network (500) between the coupling network for generating quadrature signals and the active amplitude control module, wherein 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), the third inductor (503) and the fifth capacitor (504) are connected in series, the fourth inductor (505) and the sixth capacitor (506) are connected in series, the fifth capacitor (504) and the sixth capacitor (506) have the same size, the third capacitor (501) and the fourth capacitor (502) have the same size, the third inductor (503) and the fourth inductor (505) have the same size, the negative terminals of the third capacitor (501), the fourth capacitor (502), the fifth capacitor (504) and the sixth capacitor (506) are connected to the four-way input of the active amplitude control module, so as to optimize the phase bandwidth of the quadrature signals and improve the phase shifting precision.

2. An active phase shifter of the vector modulator type according to claim 1, characterized in that: The coupling network (100) for generating quadrature signals is any one of an all-pass filter based on LC resonant network, a 90° coupler based on transformer or an R-C polyphase filter; the coupling network (100) for generating quadrature signals can also adjust the phase of signals, and improve the phase shift precision of the phase shifter; the coupling network for generating quadrature signals converts one differential input signal VIN+ and VIN- into two differential signals V I,IN+ , V I,IN , and V Q,IN+ , V Q,IN- .

3. The vector modulation type active phase shifter according to claim 1, characterized in that: The coupling network (100) for generating quadrature signals is an all-pass filter based on LC resonance network; the coupling network for generating 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 terminals of the first inductor (101) and the first capacitor (103) are connected together as the input positive terminal of the coupling network, the positive terminals of the second inductor (102) and the second capacitor (104) are connected together as the input negative terminal of the coupling network, the first resistor (105) is connected across the negative terminal of the second inductor (102) and the negative terminal of the first capacitor (103), the second resistor (106) is connected across the negative terminal of the first inductor (101) and the negative terminal of the second capacitor (104), the positive terminal of the first resistor (105) is the positive terminal V I,IN+ of the output I channel of the coupling network, the negative terminal of the first resistor (105) is the negative terminal V Q,IN- of the output Q channel of the coupling network, the positive terminal of the second resistor (106) is the positive terminal V Q,IN+ of the output Q channel of the coupling network, and the negative terminal of the second resistor (106) is the negative terminal V I,IN- of the output I channel of the coupling network; the first resistor (105) and the second resistor (106) are adjustable in resistance value and are used for adjusting the signal phase of the coupling network for generating quadrature signals.

4. A vector modulation type active phase shifter based on the one according to claim 1, characterized by: The phase compensation network (500) can expand the bandwidth of the coupling network (100) for generating quadrature signals and reduce the error of the amplitude and phase of the quadrature signals.

5. The vector modulation type active phase shifter according to claim 1, characterized by: The first transistor (201) and the second transistor (202) in the common source transistor have the same size, and the third transistor (203), the fourth transistor (204), the fifth transistor (205) and the sixth transistor (206) in the common gate transistor array unit have the same size.

6. An active phase shifter of the vector modulator type according to claim 1, characterized in that: A plurality of parallel common gate transistor array units, the total size of the common gate transistors in each unit is increased by a proportional coefficient N, and the proportional coefficient N is any positive real number.

7. An active phase shifter of the vector modulator type 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.

8. An active phase shifter of the vector modulator type according to claim 1, characterized in that: The power combining and output matching network (400) comprises a power combiner and a post-combining output matching network, the power combiner is composed of a first transmission line (401), a second transmission line (402), a third transmission line (403) and a fourth transmission line (404), and the positive end VI of an I-channel differential signal is connected to the first transmission line (401), the negative end VI of the I-channel differential signal is connected to the second transmission line (402), the positive end VQ of a Q-channel differential signal is connected to the third transmission line (403), and the negative end VQ of the Q-channel differential signal is connected to the fourth transmission line (404); the post-combining output matching network is composed of a first transformer (406) with a coupling coefficient k, a seventh capacitor (405) and an eighth capacitor (407), the coupling coefficient k determines the bandwidth of the matching network, the center tap of the primary coil of the first transformer (406) is connected to a power supply, and the differential output of the matching network is the output signals VOUT+ and VOUT- of a phase shifter. OUT+ the positive end VQ of the Q-channel differential signal OUT+ the power combining signal V C,OUT+ the negative end VI of the I-channel differential signal OUT- the negative end VQ of the Q-channel differential signal OUT- the power combining signal V C,OUT- the post-combining I-channel differential signal as the input of the output matching network; the output matching network is composed of a first transformer (406) with a coupling coefficient k, a seventh capacitor (405) and an eighth capacitor (407), the coupling coefficient k determines the bandwidth of the matching network, the center tap of the primary coil of the first transformer (406) is connected to a power supply, and the differential output of the matching network is the output signals VOUT+ and VOUT- of a phase shifter.

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