Broadband low-insertion-loss differential bridge T-type phase shifter circuit
By introducing differential virtual ground and differential bridge structures into the bridge T-type phase shifter, the existing bridge T-type phase shifter has solved the problems of low broadband phase shift accuracy and large insertion loss, achieving higher broadband phase shift accuracy and lower insertion loss, and improving the performance of phased array radar.
Patent Information
- Application Number
- CN202421858673.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-02
- Publication Date
- 2025-05-09
- Estimated Expiration
- 2034-08-02
AI Technical Summary
The existing bridge T-type phase shifting amount generated by the existing bridge T-type phase shifter in the high frequency band is greater than that in the low frequency band, resulting in low broadband phase shifting accuracy and large insertion loss, affecting the target recognition accuracy and system energy consumption of phased array radar.
The differential bridge T-type phase shifter circuit is adopted, and a differential virtual ground is introduced through the combination of the positive branch and the negative branch horizontal phase shifter unit and the vertical phase shifter unit to form a differential bridge T-type phase shifter structure, reducing the problem of increasing phase shifting from the use of independent long inductors.
The phase response flatness in the broadband is improved, the phase shift accuracy in the wideband is improved, and the insertion loss of the phase shifter is reduced, and the performance of the broadband phased array radar is improved.
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Figure CN222852254U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of microwave radio frequency, in particular to a broadband low insertion loss differential bridge T-type phase shifter circuit. Background Art
[0002] Phased array radar is a radar that changes the direction of the beam by changing the phase of the radar wave, thereby completing the monitoring task of the target area in an electronic scanning manner. The phased array antenna surface can be installed with hundreds or thousands of antenna elements, each of which contains a phase shifter circuit that can control the phase difference of each antenna in the antenna array, thereby adjusting the radar beam. The phase shifting accuracy of the phase shifter determines the pointing accuracy of the radar wave. In broadband phased array radar applications, the radar wave needs to maintain precise pointing within the entire working bandwidth, otherwise it will affect the accuracy of the radar's target identification. At the same time, the low insertion loss characteristics of the phase shifter can reduce the pressure on the gain compensation amplifier in the RF channel of the phased array radar and reduce the energy consumption of the radar system.
[0003] The commonly used phase shifter structures in phased array radar antenna elements include: high-low pass phase shifter, reflective phase shifter, and bridge T-type phase shifter. The bridge T-type phase shifter uses a switch to switch states. It can be equivalent to a bandpass network in the reference state and a T-type low-pass network in the phase shift state, generating a lag phase to achieve a specific phase shift. The bridge T-type phase shifter structure is suitable for the control of small and medium phases, but there is a significant disadvantage. The phase shift generated in the high frequency band is greater than the phase shift generated in the low frequency band, which results in the phase shifter being unable to achieve good broadband phase shift accuracy. In order to achieve the rated phase shift, a large insertion loss will be caused. The broadband phase shifter has low broadband phase shift accuracy, which greatly reduces the accuracy of broadband phased array radar in target recognition. The large insertion loss of the phase shifter also leads to higher energy consumption of the radar system. Therefore, how to expand the broadband phase shift accuracy of the T-type phase shifter and reduce the insertion loss has always been a research hotspot. Utility Model Content
[0004] The purpose of the utility model is to provide a broadband low insertion loss differential bridge T-type phase shifter circuit to improve the phase response flatness within the broadband, enhance the phase shifting accuracy within the wide frequency band, and reduce the insertion loss of the phase shifter to enhance the performance of broadband phased array radar.
[0005] In order to achieve the above-mentioned purpose, the technical methods adopted by the utility model are as follows:
[0006] A broadband low insertion loss differential bridge T-type phase shifter circuit comprises a positive branch horizontal phase shifter unit, a negative branch horizontal phase shifter unit and a vertical phase shifter unit, wherein the positive branch horizontal phase shifter unit comprises a first transistor and a first center tap inductor, wherein two ends of the first center tap inductor are connected in parallel to the source and drain of the first transistor, and the gate of the first transistor is used to input a control signal; the negative branch horizontal phase shifter unit comprises a second transistor and a second center tap inductor, wherein two ends of the second center tap inductor are connected in parallel to the source and drain of the second transistor, and the gate of the second transistor is used to input a control signal; a differential signal virtual ground point is located in the middle of the vertical phase shifter unit, and the differential signal virtual ground point divides the vertical phase shifter unit into two parts, both parts of the vertical phase shifter unit have a control signal input end, a part of the vertical phase shifter unit is connected to the center tap of the first center tap inductor, and forms a T-type phase shifter structure with the positive branch horizontal phase shifter unit; another part of the vertical phase shifter unit is connected to the center tap of the second center tap inductor, and forms a T-type phase shifter structure with the negative branch horizontal phase shifter unit.
[0007] As a limitation: the vertical phase shift unit includes a third transistor, a fourth transistor, a fifth transistor, a first capacitor, a second capacitor, a first inductor, a second inductor, a first resistor and a second resistor, the center tap of the first center-tapped inductor is respectively connected to one end of the first capacitor and the drain of the third transistor, the other end of the first capacitor is respectively connected to one end of the first resistor and one end of the second capacitor, the other end of the second capacitor is respectively connected to the center tap of the second center-tapped inductor and the drain of the fifth transistor; the gate of the third transistor is used to input a control signal, the source of the third transistor is respectively connected to one end of the first inductor and the drain of the fourth transistor, the gate of the fourth transistor is used to input a control signal, the source of the fourth transistor is respectively connected to the source of the fifth transistor and one end of the second inductor, the gate of the fifth transistor is used to input a control signal, the other end of the second inductor is respectively connected to one end of the second resistor and the other end of the first inductor, the other end of the first resistor and the other end of the second resistor are both connected to a virtual ground.
[0008] As a further limitation: the inductance value of the first center-tapped inductor is smaller than the inductance value of the first inductor, and the inductance value of the second center-tapped inductor is smaller than the inductance value of the second inductor.
[0009] As a further limitation: the positive branch horizontal phase shift unit also includes a third resistor, one end of the third resistor is connected to the drain of the first transistor, and the other end of the third resistor is connected to the virtual ground; the negative branch horizontal phase shift unit also includes a fourth resistor, one end of the fourth resistor is connected to the drain of the second transistor, and the other end of the fourth resistor is connected to the virtual ground.
[0010] Due to the adoption of the above solution, the utility model has the following beneficial effects compared with the prior art:
[0011] The utility model provides a broadband low insertion loss differential bridge T-type phase shifter circuit, comprising a positive branch horizontal phase shifter unit, a negative branch horizontal phase shifter unit and a vertical phase shifter unit, a differential virtual ground is introduced in the middle of the vertical phase shifter unit, the positive branch horizontal phase shifter unit and the vertical phase shifter unit constitute a T-type phase shifter structure, the negative branch horizontal phase shifter unit and the vertical phase shifter unit constitute a T-type phase shifter structure, and then constitute a differential bridge T-type phase shifter, and realize the phase shift of the signal by switching between the reference state and the phase shift state; adopting a differential structure, and connecting the center tap inductor in parallel with the source and drain of the transistor, compared with two independent inductors in parallel, a shorter inductor length can be used to achieve the same inductance, thereby reducing the problem of increased phase shift in the high frequency band caused by the use of independent and long inductors, improving the phase response flatness in the broadband, and improving the phase shift accuracy in the wide frequency band. At the same time, the insertion loss of the phase shifter is reduced, and the performance of the broadband phased array radar is improved; the introduction of the differential virtual ground avoids the introduction of grounding holes in the layout, and saves the layout area of the bridge T-type phase shifter.
[0012] The utility model is suitable for controlling the phase in an array element of a broadband phased array radar antenna. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention is described in further detail below in conjunction with the accompanying drawings and specific embodiments.
[0014] Figure 1 This is a principle block diagram of a broadband low insertion loss differential bridge T-type phase shifter circuit according to an embodiment of the utility model;
[0015] Figure 2 The circuit diagram of the broadband low insertion loss differential bridge T-type phase shifter circuit of the utility model embodiment;
[0016] Figure 3 This is a layout of the center tap inductor in an embodiment of the utility model;
[0017] Figure 4 This is a reference state equivalent diagram of a broadband low insertion loss differential bridge T-type phase shifter according to an embodiment of the utility model;
[0018] Figure 5 This is a phase shift state equivalent diagram of a broadband low insertion loss differential bridge T-type phase shifter according to an embodiment of the utility model;
[0019] Figure 6 This is the Q value simulation comparison curve of the center-tapped inductor and the independent inductor;
[0020] Figure 7 It is a comparison curve of the performance of the phase shifter according to the embodiment of the utility model and the traditional phase shifter. DETAILED DESCRIPTION
[0021] The present invention is further described below in conjunction with embodiments. However, those skilled in the art should understand that the present invention is not limited to the following embodiments, and any improvements and equivalent changes made based on the specific embodiments of the present invention are within the scope of protection of the claims of the present invention.
[0022] Embodiment A broadband low insertion loss differential bridge T-type phase shifter circuit
[0023] A broadband low insertion loss differential bridge T-type phase shifter circuit, its principle block diagram is as follows Figure 1 As shown, it includes a positive branch horizontal phase shift unit, a negative branch horizontal phase shift unit and a vertical phase shift unit. The middle of the vertical phase shift unit is a differential signal virtual point. The differential signal virtual point divides the vertical phase shift unit into two parts. One part of the vertical phase shift unit is connected to the positive branch horizontal phase shift unit, and forms a T-type phase shifter structure with the positive branch horizontal phase shift unit; the other part of the vertical phase shift unit is connected to the negative branch horizontal phase shift unit, and forms a T-type phase shifter structure with the negative branch horizontal phase shift unit; the positive branch horizontal phase shift unit and the negative branch horizontal phase shift unit, as well as the two parts of the vertical phase shift unit, all have a control signal input terminal for inputting a control signal, switching the working state of the phase shifter circuit, and realizing phase shifting of the signal.
[0024] The circuit diagram of the broadband low insertion loss differential bridge T-type phase shifter circuit of this embodiment is as follows: Figure 2 As shown, the positive branch horizontal phase shift unit includes a first transistor NM P1 , the first center tap inductor L TP and the third resistor R ref3 , the third resistor R ref3 One end of the first transistor NM is connected P1 The drain terminal, the third resistor R ref3 The other end of the first center-tapped inductor L TP The two ends of the first transistor NM are connected in parallel P1 The source and drain of the first transistor NM P1 The gate is used to input the control signal; the negative branch horizontal phase shift unit includes a second transistor NM N1 , the second center tap inductor L TN and the fourth resistor R ref4 , the fourth resistor R ref4 One end of the second transistor NM is connected N1 The drain, the fourth resistor R ref4 The other end of the second center-tapped inductor L TN The two ends of the second transistor NM are connected in parallel N1 The source and drain of the second transistor NM N1 The gate is used to input the control signal; the vertical phase shift unit includes a third transistor NM P2, the fourth transistor NM T , the fifth transistor NM N2 , the first capacitor C P1 , the second capacitor C N1 , the first inductor L P1 , the second inductor L N1 , the first resistor R ref1 and the second resistor R ref2 , the first center-tapped inductor L TP The center tap is connected to the first capacitor C P1 One end of the third transistor NM P2 The drain connection of the first capacitor C P1 The other end is connected to the first resistor R ref1 One end of the second capacitor C N1 One end of the second capacitor C N1 The other end is connected to the second center-tapped inductor L TN The center tap of the fifth transistor NM N2 The drain of the third transistor NM is connected; P2 The gate of the third transistor NM is used to input the control signal. P2 The source of the first inductor L P1 One end and the fourth transistor NM T The drain of the fourth transistor NM is connected T The gate of the fourth transistor NM is used to input a control signal. T The source of the fifth transistor NM N2 The source of the second inductor L N1 One end of the fifth transistor NM is connected N2 The gate is used to input the control signal, and the second inductor L N1 The other end is connected to the second resistor R ref2 One end of the first inductor L P1 The other end is connected to the first resistor R ref1 The other end and the second resistor R ref2 The other end of the first resistor R ref1 , the second resistor R ref2 , the third resistor R ref3 and the fourth resistor R ref4 The first transistor NM provides a DC reference potential for the corresponding circuit node. P1 The source of the second transistor NM N1 The source of the first transistor NM is connected to the input terminal of the signal. P1 The drain of the second transistor NM N1 The drain is connected to the output terminal of the signal.
[0025] like Figure 3As shown, in this embodiment, the first center tap inductor L TP and the second center-tapped inductor L TN All use octagonal center-tapped inductors with two turns of winding coil. The first center-tapped inductor L TP The inductance value is smaller than the first inductor L P1 The inductance value of the second center tap inductor L TN The inductance value is smaller than the second inductor L N1 The sense value.
[0026] The control signals vc and vcn determine the working state of the broadband low insertion loss differential bridge T-type phase shifter circuit. When the control signal vc is at a low level, the control signal vcn is at a high level, and the phase shifter works in the reference state. When the control signal vc is at a high level, the control signal vcn is at a low level, and the phase shifter works in the phase shift state.
[0027] When the phase shifter works in the reference state, Figure 4 As shown, it is a reference state equivalent circuit diagram of a broadband low insertion loss differential bridge T-type phase shifter circuit, the first transistor NM P1 , the second transistor NM N1 , the third transistor NM P2 and the fifth transistor NM N2 conduction, manifested as on-resistance R on , the fourth transistor NM T Turn off, showing the turn-off capacitor C off , at this time, the phase shifter presents the characteristics of a bandpass network. Taking the positive branch as an example, in this state, the high-frequency signal passes through the on-resistance R on Through to the output, part of the low-frequency signal passes through the first center-tapped inductor L TP and the first inductor L P1 Entering the differential virtual ground, the phase shifter presents a reference phase state. TP The inductance value is much smaller than the first inductor L P1 , so the first center-tapped inductor L TP The negative branch has the same principle as the positive branch and will not be described in detail here.
[0028] When the phase shifter works in the phase shift state, Figure 5 As shown, it is a phase shift equivalent circuit diagram of a broadband low insertion loss differential bridge T-type phase shifter circuit. The first transistor NM P1 , the second transistor NM N1 , the third transistor NM P2 and the fifth transistor NM N2 Turn off, showing the turn-off capacitor C off , the fourth transistor NM T conduction, manifested as on-resistance Ron , at this time, the phase shifter presents a low-pass network characteristic. Taking the positive branch as an example, in this state, due to the first transistor NM in the path P1 When the circuit is turned off, the signal cannot pass directly and can only flow through the first center-tapped inductor L. TP to the output, and through the first center-tapped inductor L TP , the first capacitor C P1 Therefore, the first center-tapped inductor L TP In this phase shift state, it plays the main role of signal phase shift. The first center tap inductor L TP The performance of the broadband low insertion loss differential bridge T-type phase shifter circuit largely determines the phase shift accuracy and insertion loss. The first center tap inductor L TP The winding coils on both sides of the center tap will produce positive mutual inductance while producing self-inductance, such as Figure 3 As shown, the coils wound on one side are coil 1 and coil 2, and the coils wound on the other side are coil 3 and coil 4. The self-inductance generated by coil 1 and coil 2 is L S1 ′, the mutual inductance value is M 1,2 , the self-inductance generated by coil 3 and coil 4 is L S2 ′, the mutual inductance value is M 3,4 , then the first center-tapped inductor L TP The calculation formula of the inductance value is:
[0029] L TP =L S1 ′+L S2 ′+M 1,2 +M 3,4 =L S1 +L S2
[0030] With two independent series inductors L connected in parallel at the source and drain of the transistor S1 and L S2 Compared to achieve the same phase shift, the first center tap inductor L TP The self-inductance of the wound coils on both sides is smaller than the inductance of two independent inductors connected in series. The introduced center-tap inductor, due to the existence of positive mutual inductance, makes the required self-inductance smaller than the independent inductor. A shorter inductor length can be used to achieve the same inductance, which reduces the problem of increased phase shift in the high-frequency band caused by the use of independent and long inductors, improves the phase response flatness within the broadband, and enhances the phase shift accuracy within the wide frequency band.
[0031] The inductor Q value can be used to characterize the inductor loss. The calculation formula of the inductor Q value is Q = ωL / r, where ω is the angular frequency, L is the inductance value, and r is the inductor parasitic resistance. Due to the existence of mutual inductance, the center-tapped inductor reduces the self-inductance requirement, reduces the inductor parasitic resistance r, increases the Q value, and reduces the inductor loss, thereby reducing the insertion loss of the phase shifter. Figure 6 The Q value simulation of the center-tapped inductor is compared with the Q value simulation of the independent inductor. Figure 6 It can be seen that at 20GHz, the Q value of the center-tapped inductor increases by 2.
[0032] The 45° phase shifter of this embodiment is used for simulation comparison with the traditional differential bridge T-type 45° phase shifter, and the comparison parameters include phase shift amount, insertion loss in phase shift state, and input and output return loss in phase shift state. The simulation curve is shown in FIG. Figure 7 As shown, it can be seen from the phase shift simulation curve that the phase shift of the traditional differential bridge T-type 45° phase shifter drops rapidly in the high frequency band, resulting in increased fluctuations in the phase shift degree band, affecting the broadband phase shift accuracy. The phase shift of the 45° phase shifter of this embodiment changes smoothly in the entire 12-18GHz frequency band, with very small fluctuations, which improves the broadband phase shift accuracy of the phase shifter; it can be seen from the input and output return loss simulation curve that the input and output standing waves of the 45° phase shifter of this embodiment in the 12-18GHz broadband are significantly smaller than those of the traditional differential bridge T-type 45° phase shifter, which improves the phase response flatness in the broadband and improves the broadband phase shift accuracy of the phase shifter; it can be seen from the phase shifter insertion loss simulation curve that the insertion loss of the 45° phase shifter of this embodiment is improved by 0.2dB compared with the traditional differential bridge T-type 45° phase shifter, which improves the broadband phase shift accuracy of the phase shifter.
Claims
1. A broadband low insertion loss differential bridge T-type phase shifter circuit, characterized in that: It includes a positive branch horizontal phase shift unit, a negative branch horizontal phase shift unit and a vertical phase shift unit. The positive branch horizontal phase shift unit includes a first transistor and a first center-tapped inductor, the two ends of the first center-tapped inductor are connected in parallel to the source and drain of the first transistor, and the gate of the first transistor is used to input a control signal; the negative branch horizontal phase shift unit includes a second transistor and a second center-tapped inductor, the two ends of the second center-tapped inductor are connected in parallel to the source and drain of the second transistor, and the gate of the second transistor is used to input a control signal; the middle of the vertical phase shift unit is a differential signal virtual ground point, the differential signal virtual ground point divides the vertical phase shift unit into two parts, both parts of the vertical phase shift unit have a control signal input end, a part of the vertical phase shift unit is connected to the center tap of the first center-tapped inductor, and forms a T-type phase shifter structure with the positive branch horizontal phase shift unit; Another part of the vertical phase shift unit is connected to the center tap of the second center tap inductor, and forms a T-type phase shifter structure with the negative branch horizontal phase shift unit.
2. A broadband low insertion loss differential bridge T-type phase shifter circuit according to claim 1, characterized in that: The vertical phase shift unit includes a third transistor, a fourth transistor, a fifth transistor, a first capacitor, a second capacitor, a first inductor, a second inductor, a first resistor and a second resistor. The center tap of the first center-tapped inductor is respectively connected to one end of the first capacitor and the drain of the third transistor, the other end of the first capacitor is respectively connected to one end of the first resistor and one end of the second capacitor, and the other end of the second capacitor is respectively connected to the center tap of the second center-tapped inductor and the drain of the fifth transistor; the gate of the third transistor is used to input a control signal, the source of the third transistor is respectively connected to one end of the first inductor and the drain of the fourth transistor, the gate of the fourth transistor is used to input a control signal, the source of the fourth transistor is respectively connected to the source of the fifth transistor and one end of the second inductor, the gate of the fifth transistor is used to input a control signal, the other end of the second inductor is respectively connected to one end of the second resistor and the other end of the first inductor, and the other end of the first resistor and the other end of the second resistor are both connected to a virtual ground.
3. A broadband low insertion loss differential bridge T-type phase shifter circuit according to claim 2, characterized in that: The inductance value of the first center-tapped inductor is smaller than the inductance value of the first inductor, and the inductance value of the second center-tapped inductor is smaller than the inductance value of the second inductor.
4. A broadband low insertion loss differential bridge T-type phase shifter circuit according to any one of claims 1 to 3, characterized in that: The positive branch horizontal phase shift unit also includes a third resistor, one end of the third resistor is connected to the drain of the first transistor, and the other end of the third resistor is connected to the virtual ground; the negative branch horizontal phase shift unit also includes a fourth resistor, one end of the fourth resistor is connected to the drain of the second transistor, and the other end of the fourth resistor is connected to the virtual ground.