Active phase shift circuit and active phase shifter

Abstract

The invention provides an active phase shift circuit and an active phase shifter. An orthogonal all-pass filtering module processes a differential input signal and outputs a first signal and a second signal with orthogonal phases; each attenuation module attenuates the specified signal to obtain an attenuated signal; the attenuation module comprises a numerical control attenuator and a voltage control attenuator which are connected with each other; the numerical control attenuator is an n-shaped attenuation network composed of resistors with preset resistance values so as to isolate the orthogonal all-pass filtering module and the voltage-controlled attenuator. The amplification module carries out vector synthesis on each attenuation signal to obtain a synthesis signal. According to the circuit, each attenuation module comprises a numerical control attenuator and a voltage-controlled attenuator which are connected with each other, and the numerical control attenuator is an n-shaped attenuation network composed of resistors with preset resistance values, so that the fluctuation of an input load of the voltage-controlled attenuator can be weakened by a fixed preset resistance value, and the orthogonal performance of the orthogonal all-pass filter is improved; and the phase fluctuation after the overall vector synthesis is reduced, so that the overall performance of the active phase shift circuit is improved.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to an active phase shift circuit and an active phase shifter. Background Art

[0002] Currently, millimeter-wave phase shifters are primarily categorized as active and passive. Generally speaking, passive phase shifters offer high robustness, with minimal performance fluctuations over process, temperature, and voltage, but they also have larger chip area and insertion loss. Active phase shifters, on the other hand, offer smaller chip area and lower insertion loss, but suffer from poor robustness, large fluctuations, and instability. For scenarios requiring high cost reduction, chip size and power consumption are key requirements, making active phase shifters more suitable. Active phase shifters offer two options for attenuating the two orthogonal I / Q signals: a passive voltage-controlled attenuator (VCA) or a current-steering structure. Because the passive VCA offers advantages over the current-steering structure in terms of simplicity, chip size, and power consumption, the VCA structure is the preferred choice. However, in traditional structures, a quadrature all-pass filter is typically directly cascaded with the VCA. Fluctuations in the VCA's input load can affect the quadrature performance of the VCA, causing phase fluctuations after vector synthesis, which reduces the overall performance of the active phase shifter. Summary of the Invention

[0003] The object of the present invention is to provide an active phase shift circuit and an active phase shifter to improve the orthogonality performance of an orthogonal all-pass filter, reduce the phase fluctuation after the overall vector synthesis, and thus improve the overall performance of the active phase shift circuit.

[0004] The present invention provides an active phase-shifting circuit, which includes: an orthogonal full-pass filtering module for receiving a differential input signal, processing the differential input signal, and outputting a first signal and a second signal with orthogonal phases; wherein the in-phase positive terminal and the in-phase negative terminal corresponding to the first signal, and the orthogonal positive terminal and the orthogonal negative terminal corresponding to the second signal are respectively connected to corresponding attenuation modules; each attenuation module is used to attenuate a specified signal to obtain an attenuated signal; wherein the attenuation module includes a digitally controlled attenuator and a voltage-controlled attenuator connected to each other; the digitally controlled attenuator is a π-type attenuation network composed of resistors with preset resistance values; the digitally controlled attenuator is used to electrically isolate the orthogonal full-pass filtering module and the voltage-controlled attenuator; the specified signal is: an in-phase positive signal output from the in-phase positive terminal, an in-phase negative signal output from the in-phase negative terminal, a quadrature positive signal output from the quadrature positive terminal, or a quadrature negative signal output from the quadrature negative terminal; and an amplification module is used to perform vector synthesis processing on the attenuated signals output by each attenuation module to obtain a synthesized signal.

[0005] Furthermore, the attenuation module also includes: a first capacitor, the first end of the first capacitor is connected to the orthogonal all-pass filtering module; the second end of the first capacitor is connected to the input end of the digitally controlled attenuator; the output end of the digitally controlled attenuator is connected to the input end of the voltage-controlled attenuator, and the output end of the voltage-controlled attenuator is connected to the amplification module.

[0006] Furthermore, the digitally controlled attenuator includes: a second capacitor, wherein a first end of the second capacitor is connected to a second end of the first capacitor; a first resistor, wherein a first end of the first resistor is connected to a first end of the second capacitor, and a second end of the first resistor is connected to a second end of the second capacitor; a second resistor, wherein a first end of the second resistor is connected to a first end of the first resistor; a third resistor, wherein a first end of the third resistor is connected to a second end of the second resistor; a third capacitor, wherein a first end of the third capacitor is connected to a first end of the third resistor; and a second end of the third capacitor is connected to a second end of the third resistor.

[0007] A first switching tube, wherein the first end of the first switching tube is connected to the first end of the second resistor, the second end of the first switching tube is connected to the second end of the second resistor, and the third end of the first switching tube is connected to a preset first control circuit; a second switching tube, wherein the first end of the second switching tube is grounded, the second end of the second switching tube is connected to the second end of the first resistor; and the third end of the second switching tube is connected to the preset second control circuit; a third switching tube, wherein the first end of the third switching tube is grounded, the second end of the third switching tube is connected to the second end of the third resistor; and the third end of the third switching tube is connected to a preset third control circuit.

[0008] Furthermore, the resistance of the second resistor is calculated as follows:

[0009]

[0010] Among them, R se Indicates the resistance of the second resistor; R load Indicates the target interface impedance of the orthogonal all-pass filter module; A indicates the attenuation;

[0011]

[0012] Wherein, Pin represents the preset power of the differential input signal; Pout represents the preset power of the composite signal.

[0013] Furthermore, the resistance values of the first resistor and the third resistor are calculated as follows:

[0014]

[0015] Among them, R sh Indicates the resistance value of the first resistor or the third resistor.

[0016] Furthermore, the target interface impedance is a first interface impedance or a second interface impedance; the first interface impedance is connected between the in-phase positive terminal and the quadrature negative terminal; and the second interface impedance is connected between the in-phase negative terminal and the quadrature positive terminal.

[0017] Furthermore, the first interface impedance is the same as the second interface impedance.

[0018] Furthermore, the maximum attenuation range of the digitally controlled attenuator is 4 dB.

[0019] Furthermore, the voltage-controlled attenuator includes: a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor connected in series in sequence, with the other end of the fourth resistor connected to the output end of the digitally controlled attenuator; the other end of the seventh resistor is grounded; an eighth resistor and a ninth resistor connected in series in sequence, with the other end of the eighth resistor connected to the output end of the digitally controlled attenuator; a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor connected in series in sequence, with the other end of the tenth resistor connected to the other end of the ninth resistor; the other end of the thirteenth resistor is grounded; a fourth switch tube, with a first end and a second end of the fourth switch tube respectively connected to the two ends of the fourth resistor; and a third end of the fourth switch tube connected to a preset fourth control circuit.

[0020] A fifth switch tube, wherein the first end and the second end of the fifth switch tube are respectively connected to the two ends of the fifth resistor; the third end of the fifth switch tube is connected to a preset fifth control circuit; a sixth switch tube, wherein the first end and the second end of the sixth switch tube are respectively connected to the two ends of the sixth resistor; the third end of the sixth switch tube is connected to a preset sixth control circuit; a seventh switch tube, wherein the first end and the second end of the seventh switch tube are respectively connected to the two ends of the seventh resistor; the third end of the seventh switch tube is connected to the preset seventh control circuit; an eighth switch tube, wherein the first end and the second end of the eighth switch tube are respectively connected to the two ends of the eighth resistor; the third end of the eighth switch tube is connected to the preset eighth control circuit; a ninth switch tube, wherein the first end and the second end of the ninth switch tube are respectively connected to the two ends of the ninth resistor; The third end of the switch tube is connected to the preset ninth control circuit; the tenth switch tube, the first end and the second end of the tenth switch tube are respectively connected to the two ends of the tenth resistor; the third end of the tenth switch tube is connected to the preset tenth control circuit; the eleventh switch tube, the first end and the second end of the eleventh switch tube are respectively connected to the two ends of the eleventh resistor; the third end of the eleventh switch tube is connected to the preset eleventh control circuit; the twelfth switch tube, the first end and the second end of the twelfth switch tube are respectively connected to the two ends of the twelfth resistor; the third end of the twelfth switch tube is connected to the preset twelfth control circuit; the thirteenth switch tube, the first end and the second end of the thirteenth switch tube are respectively connected to the two ends of the thirteenth resistor; the third end of the thirteenth switch tube is connected to the preset thirteenth control circuit.

[0021] The present invention provides an active phase shifter, comprising any one of the above-mentioned active phase shift circuits.

[0022] The present invention provides an active phase shift circuit and active phase shifter. A quadrature all-pass filter module processes a differential input signal and outputs a first signal and a second signal with orthogonal phases. Each attenuation module attenuates a designated signal to produce an attenuated signal. The attenuation module includes interconnected digitally controlled attenuators and voltage-controlled attenuators. The digitally controlled attenuators are π-type attenuation networks composed of resistors with preset values to isolate the quadrature all-pass filter module and the voltage-controlled attenuator. An amplification module performs vector synthesis on each attenuated signal to produce a synthesized signal. The circuit includes interconnected digitally controlled attenuators and voltage-controlled attenuators in each attenuation module. Because the digitally controlled attenuators are π-type attenuation networks composed of resistors with preset values, fluctuations in the voltage-controlled attenuator input load can be mitigated by the fixed, preset resistance values, thereby improving the orthogonality performance of the quadrature all-pass filter and reducing phase fluctuations after overall vector synthesis, thereby improving the overall performance of the active phase shift circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A schematic diagram of an active phase shift circuit provided by an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of another active phase shift circuit provided by an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of a simulation result provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Phase shifting is a key function in beamforming. Currently, millimeter-wave phase shifters are categorized into two main types: active and passive. These are further subdivided into various structures, each with its own advantages and disadvantages, as described below.

[0029] 1. Active phase shifters are mostly based on vector synthesis, converting the differential RF signal into two orthogonal I / Q signals. After applying different attenuation to the two orthogonal signals, vector synthesis is performed, causing the synthesized signal to shift in phase relative to the original signal, thereby achieving the phase shift function. On-chip orthogonal signal generation is mostly based on quadrature all-pass filters (QAFs), which work by phase-shifting the differential signal using capacitors and inductors to achieve an orthogonal output phase relationship. Alternatively, orthogonal signals can be generated using orthogonal couplers. There are two solutions for the I / Q attenuation function, which are described below.

[0030] One is the passive voltage-controlled attenuator (VCA) solution, which adjusts the IQ gain by controlling the bias voltage of the passive voltage-controlled attenuator. Its advantages are simple structure, continuous attenuation, and high precision. Its disadvantage is that the switching tube of the passive voltage-controlled attenuator is in the linear region and is very sensitive to temperature and batch fluctuations, resulting in very large fluctuations in phase shift accuracy.

[0031] The second is a current-steering structure, which designs the IQ dual-channel amplifier as N groups of sub-cells. By switching the gate voltage of each sub-cell's stacked transistors, the sub-cells are controlled, thereby controlling the current flowing through the load and achieving gain control. Its advantage lies in its relatively stable structure and low fluctuations. Its disadvantage is that attenuation accuracy depends on the size of the array. High accuracy inevitably leads to a larger array size, resulting in excessive parasitic capacitance, which affects gain and area. Furthermore, because half of the current in the current-steering structure does not flow through the load, power consumption is significantly increased.

[0032] Passive phase shifters offer significantly improved robustness compared to active phase shifters, making them less sensitive to batch, temperature, voltage, and frequency variations. However, these come at significant costs, such as insertion loss and footprint. Passive phase shifters are primarily categorized as switching-type phase shifters (STPS) and reflective-type phase shifters (RTPS).

[0033] 1. The switching phase shifter is a traditional structure that uses capacitors, inductors or transmission lines to form different high-pass and low-pass filter networks to shift the phase of the RF signal. There are three main types of switching phase shifters, as follows:

[0034] A. High-pass and low-pass structure. This involves designing two signal paths, a high-pass (CLC) and a low-pass (LCL), within the RF signal path. The phase shift values of the two networks are set to ± target value / 2, respectively. A switch switches the RF signal through the high-pass or low-pass network, achieving phase shift. This structure offers the advantage of high stability. Both the high-pass and low-pass networks can be designed according to target values, resulting in good input and output interface matching and minimal cascading effects. However, its disadvantages include high switch insertion loss (each high-pass and low-pass cell requires two switches before and after), a large on-chip footprint, low precision, discontinuous stepping, and no remediation if the process deviates.

[0035] BT / Bridged-T. The T-type structure is based on a low-pass filter (LCL) structure, using a switch bypass to switch between the reference state and the phase-shifted state. Compared to the high-pass and low-pass structures, it significantly reduces insertion loss. However, due to the inherent structural inconsistency between the reference and phase-shifted states, the input and output interfaces in the two states are poorly matched, resulting in some compromises in bandwidth and PVT fluctuations. It also faces the same accuracy issues as the high-pass and low-pass structures.

[0036] C. Pi-type / transmission line / other structures. Other types of structures also achieve phase shifting by forming different filter networks with capacitors and inductors. However, their structures are generally more complex than the previous two, and they require more inductors in terms of topology, which is not conducive to on-chip integration.

[0037] 2. A reflective phase shifter consists of two parts: a hybrid coupler and a variable load. After the signal enters the coupler input, it is split into two signals with a 90° phase difference. These two signals are then reflected by a set of variable loads and synthesized at the coupler output. By adjusting the reflection coefficient seen by the variable load, the phase of the signal after passing through the variable load can be adjusted, thereby changing the phase of the synthesized signal. Variable loads are categorized into various types, including π-type, capacitor array, and transformer. The advantages of a reflective phase shifter structure are high precision and continuous stepping. However, its disadvantages are a small dynamic range of phase shifting and high insertion loss.

[0038] In summary, millimeter-wave phase shifters each have their own advantages and disadvantages. Generally speaking, passive phase shifters have high robustness, with minimal performance fluctuations over process, temperature, and voltage, but they have large area and insertion loss. Active phase shifters have a small area and low insertion loss (or can provide gain), but they have poor robustness, large fluctuations, and instability. For scenarios with high cost reduction demands, chip size and power consumption become core requirements. Active phase shifters with a voltage-controlled attenuator structure are undoubtedly the preferred choice, but their PVT (P: Process, V: Voltage, T: Temperature) fluctuations are a key issue affecting mass production. In traditional structures, an orthogonal all-pass filter is typically directly cascaded with a voltage-controlled attenuator. Fluctuations in the voltage-controlled attenuator's input load affect the orthogonal performance of the orthogonal all-pass filter, causing phase fluctuations after the overall vector synthesis, which reduces the overall performance of the active phase shifter. Based on this, embodiments of the present invention provide an active phase shifting circuit and an active phase shifter. This technology can be applied to applications that require improved overall performance of active phase shifters.

[0039] To facilitate understanding of this embodiment, an active phase shift circuit disclosed in an embodiment of the present invention is first introduced. Figure 1 As shown, the circuit includes: an orthogonal all-pass filtering module 10, multiple attenuation modules 11, and an amplification module 12; the orthogonal all-pass filtering module 10 is used to receive a differential input signal, process the differential input signal, and output a first signal and a second signal with orthogonal phases; wherein the in-phase positive terminal and the in-phase negative terminal corresponding to the first signal, and the orthogonal positive terminal and the orthogonal negative terminal corresponding to the second signal are respectively connected to their corresponding attenuation modules 11; the above-mentioned differential input signal can be a differential radio frequency signal, etc.; in actual implementation, the orthogonal all-pass filtering module 10 can be specifically an orthogonal all-pass filter, which can convert and process the received differential input signal and output two orthogonal I / Q signals, corresponding to the above-mentioned first signal and the second signal, respectively, the in-phase positive terminal and the in-phase negative terminal corresponding to the first signal, and the orthogonal positive terminal and the orthogonal negative terminal corresponding to the second signal are all connected to their corresponding attenuation modules, the circuit structure of each attenuation module is usually the same, and the component parameters in the circuit may be the same or different.

[0040] Each attenuation module 11 is used to attenuate the specified signal to obtain an attenuated signal; wherein, the attenuation module 11 includes a digitally controlled attenuator and a voltage-controlled attenuator connected to each other; the digitally controlled attenuator is a π-type attenuation network composed of resistors with preset resistance values; the preset resistance value can be set according to actual needs; the digitally controlled attenuator is used to electrically isolate the orthogonal full-pass filter module and the voltage-controlled attenuator; that is, the orthogonal full-pass filter module and the voltage-controlled attenuator can be separated by the π-type attenuation network with preset resistance values, thereby reducing the influence of the fluctuation of the voltage-controlled attenuator on the orthogonal full-pass filter module; the specified signal is: the in-phase positive output terminal of the in-phase positive ... signal, the in-phase negative signal outputted from the in-phase negative terminal, the quadrature positive signal outputted from the quadrature positive terminal, or the quadrature negative signal outputted from the quadrature negative terminal; if the attenuation module 11 is connected to the in-phase positive terminal, the designated signal received by the attenuation module 11 is the in-phase positive signal I+; if the attenuation module 11 is connected to the in-phase negative terminal, the designated signal received by the attenuation module 11 is the in-phase negative signal I-; if the attenuation module 11 is connected to the quadrature positive terminal, the designated signal received by the attenuation module 11 is the quadrature positive signal Q+; if the attenuation module 11 is connected to the quadrature negative terminal, the designated signal received by the attenuation module 11 is the quadrature negative signal Q-. For each attenuation module 11, the attenuation module 11 can attenuate the received designated signal through an internally interconnected digitally controlled attenuator and a voltage-controlled attenuator, and output a corresponding attenuated signal.

[0041] Amplification module 12 is used to perform vector synthesis processing on the attenuated signals output by each attenuation module 11 to generate a composite signal. In actual implementation, the circuit structure of this amplification module may include bias, LCTank, etc. Each attenuation module 11 can attenuate the mutually orthogonal I / Q signals to varying degrees. Finally, amplification module 12 can perform vector synthesis on the attenuated signals output by each attenuation module 11 to generate a composite signal, resulting in a phase shift between the composite signal and the differential input signal.

[0042] The above-mentioned active phase-shifting circuit includes an interconnected digitally controlled attenuator and a voltage-controlled attenuator in each attenuation module. Since the digitally controlled attenuator is a π-type attenuation network composed of resistors with preset resistance values, the fluctuation of the input load of the voltage-controlled attenuator can be weakened by the fixed preset resistance value, thereby improving the orthogonality performance of the orthogonal all-pass filter, reducing the phase fluctuation after the overall vector synthesis, and thus improving the overall performance of the active phase-shifting circuit.

[0043] Further, such as Figure 2As shown in the figure, another active phase shift circuit is shown. As can be seen from the figure, the active phase shift circuit includes: an orthogonal all-pass filter QAF, an attenuation module connected to the in-phase positive terminal (the attenuation module connected to the in-phase negative terminal, the orthogonal positive terminal and the orthogonal negative terminal is not shown in the figure), and an amplification module. The circuit structure of the amplification module can refer to the relevant technology and will not be repeated here; Figure 2 As shown, the attenuation module also includes a first capacitor C1, a first end of which is connected to the orthogonal all-pass filter module; a second end of which is connected to the input of the digitally controlled attenuator; the capacitance of the first capacitor C1 can be set according to actual needs and is not limited here. The output of the digitally controlled attenuator is connected to the input of the voltage-controlled attenuator, and the output of the voltage-controlled attenuator is connected to the amplification module.

[0044] The orthogonal signal output by the orthogonal all-pass filter QAF is very sensitive to the subsequent load. When the subsequent load changes, its orthogonality will be affected (both the phase and amplitude will be mismatched). The traditional attenuation module adopts a voltage-controlled attenuator (VCA) structure, which uses a MOS switch tube operating in the linear region to form the resistor in the π-type attenuator network. However, due to the large performance fluctuations of the MOS switch tube in the linear region, the input impedance of the voltage-controlled attenuator (VCA) fluctuates greatly. Therefore, in the traditional structure, when the orthogonal all-pass filter QAF is directly cascaded with the voltage-controlled attenuator (VCA), the fluctuation of the input load of the voltage-controlled attenuator (VCA) will affect the orthogonal performance of the orthogonal all-pass filter QAF, causing the phase after the overall vector synthesis to fluctuate.

[0045] In this embodiment, the attenuation module is optimized. A fixed-resistance π-type attenuation network (corresponding to the aforementioned digitally controlled attenuator) is added between the quadrature all-pass filter QAF and the voltage-controlled attenuator VCA to isolate the two and reduce the impact of VCA input impedance fluctuations on the quadrature all-pass filter QAF. By optimizing the attenuation network in this way, fluctuations in the VCA input impedance are mitigated by the fixed resistor value, reducing the load process fluctuations seen by the quadrature all-pass filter QAF and thus improving the stability of the overall phase shifter.

[0046] Further, such as Figure 2 As shown, the digitally controlled attenuator includes: a second capacitor C2, a first resistor R1, a second resistor R2, a third resistor R3, a third capacitor C3, a first switch tube M1, a second switch tube M2 and a third switch tube M3;

[0047] The first end of the second capacitor C2 is connected to the second end of the first capacitor C1; the capacitance of the second capacitor C2 can be set according to actual needs and is not limited here;

[0048] A first end of the first resistor R1 is connected to a first end of the second capacitor C2, and a second end of the first resistor R1 is connected to a second end of the second capacitor C2. The resistance value of the first resistor R1 can be set according to actual needs and is not limited here.

[0049] A first end of the second resistor R2 is connected to the first end of the first resistor R1; the resistance value of the second resistor R2 can be set according to actual needs and is not limited here;

[0050] A first end of the third resistor R3 is connected to the second end of the second resistor R2; the resistance value of the third resistor R3 can be set according to actual needs and is not limited here;

[0051] A first end of the third capacitor C3 is connected to a first end of the third resistor R3; a second end of the third capacitor C3 is connected to a second end of the third resistor R3; the capacitance of the third capacitor C3 can be set according to actual needs and is not limited here;

[0052] The first switch tube M1 has a first end, a second end, and a third end. The first end of the first switch tube M1 is connected to the first end of the second resistor R2, the second end of the first switch tube M1 is connected to the second end of the second resistor R2, and the third end of the first switch tube M1 is connected to a preset first control circuit. The first switch tube M1 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the first switch tube M1 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned first control circuit can output a corresponding control signal to control the on and off of the first switch tube M1.

[0053] The second switch tube M2 has a first end, a second end, and a third end. The first end of the second switch tube M2 is grounded, and the second end of the second switch tube M2 is connected to the second end of the first resistor R1. The third end of the second switch tube M2 is connected to a preset second control circuit. The second switch tube M2 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the second switch tube M2 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned second control circuit can output a corresponding control signal to control the on and off of the second switch tube M2.

[0054] The third switch tube M3 has a first end, a second end, and a third end. The first end of the third switch tube M3 is grounded, and the second end of the third switch tube M3 is connected to the second end of the third resistor R3. The third end of the third switch tube M3 is connected to a preset third control circuit. The third switch tube M3 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the third switch tube M3 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned third control circuit can output a corresponding control signal to control the on and off of the third switch tube M3.

[0055] The following combination Figure 2 , the working principle of the active phase shift circuit is explained:

[0056] First, the orthogonal all-pass filter QAF is an LC passive network. Its principle is to pass the signal through the LC / CL network to make the phase advance 45° / delay 45° respectively. The calculation formula is as follows:

[0057] Ls=R load *Cs;

[0058]

[0059] Among them, R load is the target interface impedance; f is the operating frequency, R load and f are usually predetermined values, and the values of Ls and Cs can be calculated according to the above formula.

[0060] Figure 2 Resistors Rs1 and Rs2 are both compensation resistors, also intended to reduce the impact of subsequent-stage loads on the performance of the quadrature all-pass filter, QAF. Compensation resistors are used to lower the Q of the resonant network, compensating for phase and amplitude mismatches. This comes at the cost of significantly increased insertion loss. The values of resistors Rs1 and Rs2 need to be adjusted based on the actual circuit. However, the compensation resistors only reduce the sensitivity of the quadrature all-pass filter, QAF, to subsequent-stage loads and do not mitigate subsequent-stage load fluctuations.

[0061] The voltage-controlled attenuator (VCA) uses a MOS switch operating in the linear region to form the parallel resistor Rb (corresponding to the equivalent parallel resistor of the voltage-controlled attenuator VCA) and the series resistor Rc (corresponding to the equivalent series resistor of the voltage-controlled attenuator VCA) in the π-type attenuator network. The IV characteristic curve of the MOS switch shows that the on-resistance of a MOS switch operating in the linear region is inversely proportional to its gate voltage Vgs, as shown in the following formula:

[0062] Linear region IV characteristic curve:

[0063]

[0064] Where, Ids represents the drain current; μ represents the electron mobility (NMOS) or the hole mobility (PMOS); C ox Represents the gate oxide capacitance per unit area; W represents the width of the channel; L represents the length of the channel; V GS Represents the gate-source voltage; V th Represents the threshold voltage; V DS Represents the drain-source voltage.

[0065] Linear region on-resistance formula:

[0066]

[0067] Therefore, by adjusting the gate voltage of the MOS switch, the on-resistance of the MOS switch can be controlled, and the on-resistance values of the individual π-type network can be further adjusted to achieve signal attenuation. As can be seen from the above formula, the input impedance of the voltage-controlled attenuator (VCA) fluctuates significantly with PVT. Therefore, when the orthogonal all-pass filter (QAF) and the voltage-controlled attenuator (VCA) are directly cascaded, fluctuations in the VCA input load will affect the orthogonal performance of the orthogonal all-pass filter (QAF), causing phase fluctuations after the overall vector synthesis.

[0068] In this solution, the fixed resistor π-type attenuation network (corresponding to the above-mentioned orthogonal all-pass filter) added between the orthogonal all-pass filter QAF and the voltage-controlled attenuator VCA can isolate the two and reduce the impact of the input impedance fluctuation of the voltage-controlled attenuator VCA on the orthogonal all-pass filter QAF. The fixed resistor π-type attenuation network has the same network structure as the voltage-controlled attenuator VCA, both of which are π-type structures. The difference is that a fixed resistance resistor is used to replace the MOS switch tube in the voltage-controlled attenuator VCA. The resistance values of the series resistor and the parallel resistor of the fixed resistor π-type attenuation network determine the attenuation of the current unit; it can be calculated based on the target interface impedance and attenuation of the orthogonal all-pass filter, and the formula is as follows:

[0069] The resistance of the second resistor R2 is calculated as follows:

[0070]

[0071] Among them, R se Indicates the resistance of the second resistor; R load represents the target interface impedance of the orthogonal all-pass filter module. load The value of is usually predetermined according to actual needs; A represents the attenuation;

[0072]

[0073] Among them, Pin represents the preset power of the differential input signal; Pout represents the preset power of the composite signal; Pin and Pout are usually predetermined values based on actual needs. The attenuation A can be calculated based on these two values. Then, the attenuation A is substituted into the above formula to calculate the resistance value R of the second resistor R2. se .

[0074] Furthermore, the resistance values of the first resistor and the third resistor are calculated as follows:

[0075]

[0076] Among them, R sh Indicates the resistance of the first resistor R1 or the third resistor R3; when the resistance of the second resistor R2 is calculated, R se Finally, the target interface impedance R can be combined with the orthogonal all-pass filter module load and the attenuation A, the resistance values of the first resistor R1 and the third resistor R3 are calculated.

[0077] Therefore, its resistance value is less affected by process fluctuations, resulting in smaller attenuation dynamics and input impedance fluctuations. After inserting this fixed-resistance π-type attenuation network, the fixed resistor value attenuates the input impedance fluctuations of the voltage-controlled attenuator (VCA), reducing the process fluctuations of the load seen by the quadrature all-pass filter (QAF), thereby improving the stability of the overall phase shifter.

[0078] Furthermore, the target interface impedance R load is the first interface impedance or the second interface impedance; the first interface impedance is connected between the in-phase positive terminal and the quadrature negative terminal, such as Figure 2 The interface impedance is connected between the in-phase positive terminal corresponding to the in-phase positive signal I+ and the orthogonal negative terminal corresponding to the orthogonal negative signal Q-; the second interface impedance is connected between the in-phase negative terminal and the orthogonal positive terminal, such as Figure 2 The interface impedance connected between the in-phase negative terminal corresponding to the in-phase negative signal I- and the orthogonal positive terminal corresponding to the orthogonal positive signal Q+; in a preferred embodiment, the first interface impedance is the same as the second interface impedance.

[0079] Furthermore, the maximum attenuation range of the digitally controlled attenuator is 4 dB, that is, the maximum attenuation that the digitally controlled attenuator can apply to the received signal is 4 dB, and the adjustable attenuation covers the range from 0 dB to 4 dB.

[0080] Furthermore, the voltage controlled attenuator VCA includes:

[0081] The fourth resistor R4, the fifth resistor R5, the sixth resistor R6 and the seventh resistor R7 are connected in series in sequence, and the other end of the fourth resistor R4 is connected to the output end of the digitally controlled attenuator; the other end of the seventh resistor R7 is grounded; the resistance values of the fourth resistor R4, the fifth resistor R5, the sixth resistor R6 and the seventh resistor R7 can be set according to actual needs and are not limited here.

[0082] The eighth resistor R8 and the ninth resistor R9 are connected in series in sequence, and the other end of the eighth resistor R8 is connected to the output end of the digitally controlled attenuator; the resistance values of the eighth resistor R8 and the ninth resistor R9 can be set according to actual needs and are not limited here.

[0083] The tenth resistor R10, the eleventh resistor R11, the twelfth resistor R12 and the thirteenth resistor R13 are connected in series in sequence, and the other end of the tenth resistor R10 is connected to the other end of the ninth resistor R9; the other end of the thirteenth resistor R13 is grounded; the resistance values of the tenth resistor R10, the eleventh resistor R11, the twelfth resistor R12 and the thirteenth resistor R13 can be set according to actual needs and are not limited here.

[0084] The fourth switch tube M4 has a first end, a second end, and a third end. The first end and the second end of the fourth switch tube M4 are respectively connected to the two ends of the fourth resistor R4. The third end of the fourth switch tube M4 is connected to a preset fourth control circuit. The fourth switch tube M4 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the fourth switch tube M4 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned fourth control circuit can output a corresponding control signal to control the on and off of the fourth switch tube M4.

[0085] The fifth switch M5 has a first end, a second end, and a third end. The first end and the second end of the fifth switch M5 are respectively connected to the two ends of the fifth resistor R5. The third end of the fifth switch M5 is connected to a preset fifth control circuit. The fifth switch M5 can be selected from a suitable switch according to actual needs. For example, taking a MOS switch as an example, the first end of the fifth switch M5 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned fifth control circuit can output a corresponding control signal to control the on and off of the fifth switch M5.

[0086] The sixth switch tube M6 has a first end, a second end, and a third end. The first end and the second end of the sixth switch tube M6 are respectively connected to the two ends of the sixth resistor R6. The third end of the sixth switch tube M6 is connected to a preset sixth control circuit. The sixth switch tube M6 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the sixth switch tube M6 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The aforementioned sixth control circuit can output a corresponding control signal to control the on and off of the sixth switch tube M6.

[0087] The seventh switch tube M7 has a first end, a second end, and a third end. The first end and the second end of the seventh switch tube M7 are respectively connected to the two ends of the seventh resistor R7. The third end of the seventh switch tube M7 is connected to a preset seventh control circuit. The seventh switch tube M7 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the seventh switch tube M7 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The aforementioned seventh control circuit can output a corresponding control signal to control the on and off of the seventh switch tube M7.

[0088] The eighth switch tube M8 has a first end, a second end, and a third end. The first end and the second end of the eighth switch tube M8 are respectively connected to the two ends of the eighth resistor R8. The third end of the eighth switch tube M8 is connected to a preset eighth control circuit. The eighth switch tube M8 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the eighth switch tube M8 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned eighth control circuit can output a corresponding control signal to control the on and off of the eighth switch tube M8.

[0089] The ninth switch tube M9 has a first end, a second end, and a third end. The first end and the second end of the ninth switch tube M9 are respectively connected to the two ends of the ninth resistor R9. The third end of the ninth switch tube M9 is connected to a preset ninth control circuit. The ninth switch tube M9 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the ninth switch tube M9 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The ninth control circuit can output a corresponding control signal to control the on and off of the ninth switch tube M9.

[0090] The tenth switch tube M10 has a first end, a second end, and a third end. The first end and the second end of the tenth switch tube M10 are respectively connected to the two ends of the tenth resistor R10. The third end of the tenth switch tube M10 is connected to a preset tenth control circuit. The tenth switch tube M10 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the tenth switch tube M10 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned tenth control circuit can output a corresponding control signal to control the on and off of the tenth switch tube M10.

[0091] The eleventh switch tube M11 has a first end, a second end, and a third end. The first end and the second end of the eleventh switch tube M11 are respectively connected to the two ends of the eleventh resistor R11. The third end of the eleventh switch tube M11 is connected to a preset eleventh control circuit. The eleventh switch tube M11 can be a suitable switch tube selected according to actual needs. For example, taking a MOS switch tube as an example, the first end of the eleventh switch tube M11 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned eleventh control circuit can output a corresponding control signal to control the on and off of the eleventh switch tube M11.

[0092] The twelfth switch tube M12 has a first end, a second end, and a third end. The first end and the second end of the twelfth switch tube M12 are respectively connected to the two ends of the twelfth resistor R12. The third end of the twelfth switch tube M12 is connected to a preset twelfth control circuit. The twelfth switch tube M12 can be selected from a suitable switch tube according to actual needs. For example, taking a MOS switch tube as an example, the first end of the twelfth switch tube M12 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The above-mentioned twelfth control circuit can output a corresponding control signal to control the on and off of the twelfth switch tube M12.

[0093] The thirteenth switch M13 has a first end, a second end, and a third end. The first end and the second end of the thirteenth switch M13 are respectively connected to the two ends of the thirteenth resistor. The third end of the thirteenth switch M13 is connected to a preset thirteenth control circuit. The thirteenth switch M13 can be a suitable switch according to actual needs. For example, using a MOS switch as an example, the first end of the thirteenth switch M13 corresponds to the source, the second end corresponds to the drain, and the third end corresponds to the gate. The thirteenth control circuit can output a corresponding control signal to control the on and off of the thirteenth switch M13.

[0094] See also Figure 3The figure shows a simulation result. The horizontal axis represents the gear value. By selecting different gear values, the gate voltage of the voltage-controlled oscillator (VCA) and the network control word corresponding to the digitally controlled attenuator can be changed. The vertical axis represents the phase accuracy, which is the phase shift error of the actual phase shift value minus the theoretical phase shift value. Under different gear values, the entire attenuation module is in different attenuation states. Figure 3 The corresponding Figure 2 Simulation results corresponding to the entire active phase-shift circuit. Figure 3 The three curves in the figure correspond to the simulation results at 125°, 55° and -55° respectively. It can be seen that the fluctuation stability of the simulation results is good.

[0095] In related technologies, the significant process fluctuations in phase shifter performance in the voltage-controlled attenuator (VCA) structure are primarily due to two factors. First, fluctuations in the attenuation values of the I and Q paths of the attenuation network; second, fluctuations in the quadrature signals output by the quadrature all-pass filter (QAF). The combination of these factors causes phase fluctuations in the vector-synthesized signals. This solution proposes an innovative active phase shifter structure to improve the volatility of the quadrature signals in the QAF. Compared to traditional active vector synthesis phase shifter structures, it minimizes the impact of process fluctuations and offers greater performance stability in mass production, thus reducing PVT fluctuations.

[0096] This solution optimizes the I / Q attenuation network, specifically the aforementioned attenuation module. A first-stage 4dB dynamic range Pi-type digitally controlled attenuator (DCA) is added before the input of the traditional voltage-controlled attenuator (VCA). This combination of the DCA and the VCA achieves dual-path signal attenuation. The fixed-resistance Pi-type attenuator network isolates the VCA from the quadrature all-pass filter (QAF), minimizing the impact of VCA fluctuations on the QAF and, consequently, reducing overall vector synthesis volatility.

[0097] This circuit structure optimizes the I / Q attenuation network to reduce fluctuations in the quadrature signal output by the quadrature all-pass filter (QAF), thereby improving performance stability. Compared to commonly used active phase shifter solutions, this circuit offers a smaller chip size and lower power consumption. Combined with a correction circuit, this circuit minimizes process fluctuations in overall phase shift accuracy, parasitic amplitude modulation, and phase shift dynamics, resulting in improved stability in mass production.

[0098] An embodiment of the present invention further provides an active phase shifter, comprising any of the above-mentioned active phase shift circuits.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An active phase shift circuit, characterized in that: The circuit comprises: An orthogonal all-pass filtering module is configured to receive a differential input signal, process the differential input signal, and output a first signal and a second signal with orthogonal phases; wherein the in-phase positive terminal and the in-phase negative terminal corresponding to the first signal, and the orthogonal positive terminal and the orthogonal negative terminal corresponding to the second signal are respectively connected to their corresponding attenuation modules; Each of the attenuation modules is configured to attenuate a designated signal to obtain an attenuated signal; wherein the attenuation module comprises a digitally controlled attenuator and a voltage-controlled attenuator connected to each other; the digitally controlled attenuator is a π-type attenuation network composed of resistors with preset resistance values; the digitally controlled attenuator is configured to electrically isolate the quadrature all-pass filter module and the voltage-controlled attenuator; the designated signal is: the in-phase positive signal output by the in-phase positive terminal, the in-phase negative signal output by the in-phase negative terminal, the quadrature positive signal output by the quadrature positive terminal, or the quadrature negative signal output by the quadrature negative terminal; The amplification module is used to perform vector synthesis processing on the attenuation signal output by each attenuation module to obtain a synthesized signal.

2. The circuit according to claim 1, wherein: The attenuation module further includes: a first capacitor, wherein a first end of the first capacitor is connected to the orthogonal all-pass filter module; and a second end of the first capacitor is connected to the input end of the digitally controlled attenuator; The output end of the digitally controlled attenuator is connected to the input end of the voltage-controlled attenuator, and the output end of the voltage-controlled attenuator is connected to the amplification module.

3. The circuit according to claim 2, characterized in that The digital controlled attenuator comprises: a second capacitor, wherein a first end of the second capacitor is connected to a second end of the first capacitor; a first resistor, wherein a first end of the first resistor is connected to a first end of the second capacitor, and a second end of the first resistor is connected to a second end of the second capacitor; a second resistor, wherein a first end of the second resistor is connected to a first end of the first resistor; a third resistor, a first end of the third resistor being connected to the second end of the second resistor; a third capacitor, wherein a first end of the third capacitor is connected to the first end of the third resistor; and a second end of the third capacitor is connected to the second end of the third resistor; a first switching transistor, wherein a first end of the first switching transistor is connected to the first end of the second resistor, a second end of the first switching transistor is connected to the second end of the second resistor, and a third end of the first switching transistor is connected to a preset first control circuit; a second switch tube, wherein a first end of the second switch tube is grounded, a second end of the second switch tube is connected to the second end of the first resistor; and a third end of the second switch tube is connected to a preset second control circuit; A third switch tube, wherein a first end of the third switch tube is grounded, a second end of the third switch tube is connected to the second end of the third resistor; and a third end of the third switch tube is connected to a preset third control circuit.

4. The circuit according to claim 3, characterized in that The resistance of the second resistor is calculated as follows: Among them, R se Represents the resistance of the second resistor; R load represents the target interface impedance of the orthogonal all-pass filter module; A represents the attenuation; Wherein, Pin represents the preset power of the differential input signal; Pout represents the preset power of the composite signal.

5. The circuit according to claim 4, characterized in that The resistance values of the first resistor and the third resistor are both calculated in the following manner: Among them, R sh Indicates the resistance value of the first resistor or the third resistor.

6. The circuit according to claim 4, characterized in that The target interface impedance is a first interface impedance or a second interface impedance; the first interface impedance is connected between the in-phase positive terminal and the quadrature negative terminal; the second interface impedance is connected between the in-phase negative terminal and the quadrature positive terminal.

7. The circuit according to claim 6, characterized in that The first interface impedance is the same as the second interface impedance.

8. The circuit according to claim 1, wherein: The maximum attenuation range of the digitally controlled attenuator is 4dB.

9. The circuit according to claim 1, wherein: The voltage-controlled attenuator comprises: a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor connected in series in sequence, wherein the other end of the fourth resistor is connected to the output end of the digitally controlled attenuator; and the other end of the seventh resistor is grounded; An eighth resistor and a ninth resistor connected in series, the other end of the eighth resistor being connected to the output end of the digitally controlled attenuator; a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor connected in series in sequence, wherein the other end of the tenth resistor is connected to the other end of the ninth resistor; and the other end of the thirteenth resistor is grounded; a fourth switch tube, wherein a first end and a second end of the fourth switch tube are respectively connected to two ends of the fourth resistor; and a third end of the fourth switch tube is connected to a preset fourth control circuit; a fifth switching tube, wherein a first end and a second end of the fifth switching tube are respectively connected to two ends of the fifth resistor; and a third end of the fifth switching tube is connected to a preset fifth control circuit; a sixth switch tube, wherein a first end and a second end of the sixth switch tube are respectively connected to two ends of the sixth resistor; and a third end of the sixth switch tube is connected to a preset sixth control circuit; a seventh switching tube, wherein a first end and a second end of the seventh switching tube are respectively connected to two ends of the seventh resistor; and a third end of the seventh switching tube is connected to a preset seventh control circuit; an eighth switching tube, wherein a first end and a second end of the eighth switching tube are respectively connected to two ends of the eighth resistor; and a third end of the eighth switching tube is connected to a preset eighth control circuit; a ninth switching tube, wherein a first end and a second end of the ninth switching tube are respectively connected to two ends of the ninth resistor; and a third end of the ninth switching tube is connected to a preset ninth control circuit; a tenth switching tube, wherein a first end and a second end of the tenth switching tube are respectively connected to two ends of the tenth resistor; and a third end of the tenth switching tube is connected to a preset tenth control circuit; an eleventh switching tube, wherein a first end and a second end of the eleventh switching tube are respectively connected to two ends of the eleventh resistor; and a third end of the eleventh switching tube is connected to a preset eleventh control circuit; a twelfth switch tube, wherein a first end and a second end of the twelfth switch tube are respectively connected to two ends of the twelfth resistor; and a third end of the twelfth switch tube is connected to a preset twelfth control circuit; A thirteenth switch tube, wherein the first end and the second end of the thirteenth switch tube are respectively connected to the two ends of the thirteenth resistor; and the third end of the thirteenth switch tube is connected to a preset thirteenth control circuit.

10. An active phase shifter, characterized in that: The active phase shift circuit comprises the active phase shift circuit according to any one of claims 1 to 9.

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