An ultra-wideband small phase shift digital phase shift circuit and its simulation method

Abstract

The present invention discloses an ultra-wideband small phase shift digital phase shift circuit and a simulation method thereof, including an ultra-wideband phase shift network, wherein the ultra-wideband phase shift network adopts a bridge T-type network embedded with an all-pass network structure, and the all-pass network structure is a two-port transformer network wound with two mutually coupled inductors. The miniaturization design can be realized by combining the bridge T network structure and the ultra-wideband design can be realized by the all-pass network structure, and the bridge T network structure is fully utilized to have better performance than ordinary switches, and the bandwidth of the phase shifter made by ordinary switches is wider, the phase shifting accuracy is higher, and the return loss is better. The all-pass network is suitable for the characteristics of ultra-wideband, and the two are combined to improve the performance of small phase shift. The present application embeds the all-pass network structure between the input port and the output port of the bridge T-type network structure, which can increase the phase delay, ensure the bandwidth expansion, and also ensure that the phase shifting accuracy remains unchanged.

Description

Technical Field

[0001] The invention relates to the technical field of microwave and millimeter waves, and in particular to an ultra-wideband small phase shift digital phase shift circuit and a simulation method thereof. Background Art

[0002] In recent years, microwave monolithic integrated circuits (MMICs) have been widely used in military fields, such as electronic countermeasures, phased array radars, satellite payloads, etc., and in civilian fields, such as mobile communications, wireless local area networks, and automotive radars. The phase shifter is a two-port network that controls the phase difference between the output signal and the input signal. As the core component of the phased array system, it can quickly scan the beam, realize beam switching, and transmit signals in a specific direction. It is an indispensable device in electronic countermeasures and active phased arrays.

[0003] High bandwidth and high precision are key parameters when designing phase shifters. The structure of the CNC phase shifter can be a loading line type, a switch line type, a reflection type, a bridge T type, a high-pass and low-pass filter type. For small phase shifters such as 5.625°, 11.25°, and 22.5°, the phase shift accuracy of the overall circuit is relatively small, so when considering circuit design, the main focus is on the implementation size and matching of the circuit, while taking into account the circuit performance. For existing small phase shifters, a bridge T-type structure is generally used to design the phase shifter. The bridge T-type phase shifter uses fewer FET switches, which can effectively reduce the insertion loss. However, if you want to use a small phase shifter in an ultra-wideband scenario, the phase shift accuracy will limit the bandwidth of the bridge T-type structure and cannot be infinitely improved. Therefore, how to increase the bandwidth of a small phase shifter while ensuring that the phase shift accuracy remains unchanged is a problem that needs to be solved. Summary of the invention

[0004] The purpose of the present invention is to provide an ultra-wideband small phase shift digital phase shift circuit and a simulation method thereof. The all-pass structure can effectively expand the bandwidth and improve the phase shift accuracy. Moreover, the all-pass network is added to the bridge T structure due to its small size. The obtained phase shifter is not only miniaturized but also has a higher Q value, and can obtain a smaller insertion loss and better standing wave.

[0005] To achieve the above objectives, this application proposes the following solutions:

[0006] On the one hand, the present invention provides an ultra-wideband small phase shift digital phase shift circuit, including an ultra-wideband phase shift network, wherein the ultra-wideband phase shift network adopts a bridge T-type network embedded with an all-pass network structure, and the all-pass network structure is a two-port transformer network formed by two mutually coupled inductors.

[0007] In some specific embodiments, an input port and an output port are further included, and the all-pass network structure includes a mutual coupling inductor L1, a mutual coupling inductor L2, a capacitor C2 and a capacitor C3, wherein the capacitor C2 is connected in series between the input port and the output port, one end of the mutual coupling inductor L1 is connected to one end of the mutual coupling inductor L2, the other end of the mutual coupling inductor L1 is connected in parallel to the input port, the other end of the mutual coupling inductor L2 is connected in parallel to the output port, and a capacitor C3 connected to ground is connected in parallel between the mutual coupling inductor L1 and the mutual coupling inductor L2.

[0008] In some specific embodiments, the bridge T-type network includes an all-pass network structure, an RF switch M1, an RF switch M2, an RF switch M3, a capacitor C1, and a resonant network. The gate of the RF switch M1 is connected to the first power supply end, the drain of the RF switch M1 is connected to the input end, the capacitor C1 is connected in series between the source and the output port of the RF switch M1, the drain of the RF switch M2 is connected in parallel between the mutual coupling inductor L1 and the mutual coupling inductor L2 of the all-pass network structure, the gate of the RF switch M2 is connected to the first power supply end, the source of the RF switch M2 is connected to the drain of the RF switch M3, a resonant network is connected to the drain and source of the RF switch M3, and the gate of the RF switch M3 is connected to the second power supply end.

[0009] In some specific embodiments, the resonant network includes an inductor L3 and a capacitor C4, one end of the inductor L3 is connected in parallel between the source of the RF switch M2 and the drain of the RF switch M3, and the other end is grounded, one end of the capacitor C4 is connected to the source of the RF switch M3, and the other end is grounded.

[0010] In a second aspect, the present application provides a simulation method for an ultra-wideband small phase shift digital phase shift circuit based on the first aspect, comprising the following steps:

[0011] S1. Draw a layout of a full-pass network structure in the simulation software, and generate a symbol of a full-pass network element from the drawn full-pass network structure and store it in a PDK element library of the simulation software;

[0012] S2, calling the corresponding components in the ultra-wideband small phase shift digital phase shift circuit and the generated full network structure symbol from the PDK component library, and drawing the corresponding simulation schematic diagram of each component according to the ultra-wideband small phase shift digital phase shift circuit;

[0013] S3, setting parameters of each component in the simulation schematic diagram, simulating the simulation schematic diagram, and obtaining corresponding actual simulation results;

[0014] S4, judging whether the actual simulation result reaches the preset simulation result, if not, repeating steps S1-S4 until the preset simulation structure is reached, and obtaining the simulation parameters of each component;

[0015] S5. Convert each component into a component required by the MMIC circuit layout according to the corresponding simulation parameters.

[0016] In some specific implementation schemes, the method for drawing the full-pass network structure is: the mutual coupling inductor L1 and the mutual coupling inductor L2 are equivalent to square inductors, the mutual coupling inductor L1 and the mutual coupling inductor L2 are drawn as a two-port transformer network structure, the drawn transformer network structure is stored in a graphic template of the full-pass network element, and the element parameters drawn at this time are recorded;

[0017] The graphic template of the all-pass network element and its corresponding element parameters are assembled into a symbol of the all-pass network element and stored in the PDK element library.

[0018] In some specific embodiments, the element parameters include: order, inner circle width, inner circle size, and spacing.

[0019] In some specific implementation schemes, when drawing a simulation schematic diagram, the inductor L3 is equivalent to an octagonal spiral inductor.

[0020] The inventive concept of the present invention is:

[0021] When designing existing phase shifters with small phase shift, the main focus is on the circuit implementation size and matching degree, while taking into account the circuit performance. Since the bridge T-type phase shifter uses fewer FET switches, it can effectively reduce the insertion loss, so the small phase shifter is generally implemented using a bridge T-type structure. However, when the bandwidth reaches 111%, it has reached the ultra-wideband. For ultra-wideband, if a small phase shifter wants to achieve ultra-wideband, if a bridge T-type phase shifter or a high-pass or low-pass phase shifter is used, the phase shift accuracy can no longer be guaranteed while achieving ultra-wideband. At this time, only an all-pass or other ultra-wideband structures can be used. However, even if the all-pass network is directly used to achieve ultra-wideband, the circuit layout made based on it will be very large and cannot achieve a miniaturized design.

[0022] In view of this, in order to improve the phase shifting accuracy of the phase shifter and reduce the size of the layout, the present application combines the bridge T network structure to achieve miniaturized design and the all-pass network structure to achieve ultra-wideband design, making full use of the fact that the bridge T network structure has better performance than ordinary switches, and the phase shifter made of ordinary switches has a wider bandwidth, higher phase shifting accuracy, and better return loss. The all-pass network is suitable for ultra-wideband characteristics, and the two are combined to improve the performance of small phase shifts. The present application embeds the all-pass network structure between the input port and the output port of the bridge T-type network structure, which can increase the phase delay, ensure bandwidth expansion, and ensure that the phase shifting accuracy remains unchanged.

[0023] The present invention has the beneficial effects:

[0024] The present invention provides an ultra-wideband digital phase shift circuit that embeds an all-pass structure in a bridge T-type structure. The digital phase shift circuit transforms the bridge T-type structure, and adds an all-pass network in the bridge T structure to expand the bandwidth of the phase shift circuit, which greatly reduces the area of ​​the layout, further reduces the size of the chip, and the use of the all-pass network can extend the bandwidth of the phase shift structure, with smaller insertion loss and return loss. In addition, in the bridge T-type structure, a switch and a capacitor are connected in series to the ground, and a parallel resonant network is formed with an inductor connected in parallel to the ground to improve the standing wave of the entire phase shift unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A topological diagram of an ultra-wideband small phase shift digital phase shift circuit provided by an embodiment of the present invention;

[0026] Figure 2 Based on Figure 1 The circuit layout drawn by the circuit diagram;

[0027] Figure 3 Based on Figure 2 The return loss simulation diagram of the circuit layout in the figure, where (a) is a schematic diagram of the return loss S11 and S22 curves in the phase-shifted state and the reference state, and (b) is a schematic diagram of the return loss S33 and S44 curves in the phase-shifted state and the reference state;

[0028] Figure 4 Based on Figure 2 The circuit layout simulation diagram in, where (a) is a schematic diagram of the insertion loss fluctuation IL_Error curve in the phase-shift state and the reference state, and (b) is a schematic diagram of the insertion loss S21 and S43 curves in the phase-shift state and the reference state;

[0029] Figure 5 Based on Figure 2 The circuit layout phase shift simulation diagram in FIG. 1 , where (a) is a curve diagram of the phase shift amount PhaseE, and (b) is a curve diagram of the phase shift accuracy PhaseError;

[0030] Figure 6 This is a circuit layout simulation diagram when using a full-pass network structure;

[0031] Figure 7 Based on Figure 6 : Return loss simulation diagram, where (a) is a schematic diagram of the return loss S11 and S22 curves in the phase-shifted state and the reference state, and (b) is a schematic diagram of the return loss S33 and S44 curves in the phase-shifted state and the reference state;

[0032] Figure 8 Based on Figure 6Schematic diagram of simulation, where (a) is a schematic diagram of insertion loss fluctuation IL_Error curve in phase-shift state and reference state, and (b) is a schematic diagram of insertion loss S21 and S43 curves in phase-shift state and reference state;

[0033] Fig. 9 Based on Figure 6 Phase shift simulation diagram, where (a) is a schematic diagram of the phase shift accuracy PhaseError curve, and (b) is a schematic diagram of the phase shift amount PhaseE curve;

[0034] Fig.10 This is a circuit layout simulation diagram when a bridge T-type structure is used;

[0035] Fig.11 Based on Fig.10 : Return loss simulation diagram, where (a) is a schematic diagram of the return loss S11 and S22 curves in the phase-shifted state and the reference state, and (b) is a schematic diagram of the return loss S33 and S44 curves in the phase-shifted state and the reference state;

[0036] Fig.12 Based on Fig.10 Schematic diagram of simulation, where (a) is a schematic diagram of insertion loss fluctuation IL_Error curve in phase-shift state and reference state, and (b) is a schematic diagram of insertion loss S21 and S43 curves in phase-shift state and reference state;

[0037] Fig.13 Based on Fig.10 Phase shift simulation diagram, where (a) is a curve diagram of the phase shift amount PhaseE, and (b) is a curve diagram of the phase shift accuracy PhaseError. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0040] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0041] Additionally, descriptions of well-known structures, functions, and configurations may be omitted for clarity and conciseness.One of ordinary skill in the art will recognize that various changes and modifications may be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0042] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0043] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0044] Example 1

[0045] like Figure 1 As shown, this embodiment provides an ultra-wideband small phase shift digital phase shift circuit, including an ultra-wideband phase shift network, wherein the ultra-wideband phase shift network adopts a bridge T-type network embedded with an all-pass network structure, and the all-pass network structure is a two-port transformer network formed by two mutually coupled inductors.

[0046] Specifically, it also includes an input port and an output port, and the all-pass network structure includes a mutual coupling inductor L1, a mutual coupling inductor L2, a capacitor C2 and a capacitor C3, wherein the capacitor C2 is connected in series between the input port and the output port, one end of the mutual coupling inductor L1 is connected to one end of the mutual coupling inductor L2, the other end of the mutual coupling inductor L1 is connected in parallel to the input port, the other end of the mutual coupling inductor L2 is connected in parallel to the output port, and a capacitor C3 connected to the ground is connected in parallel between the mutual coupling inductor L1 and the mutual coupling inductor L2.

[0047] Specifically, the bridge T-type network includes an all-pass network structure, an RF switch M1, an RF switch M2, an RF switch M3, a capacitor C1, and a resonant network. The gate of the RF switch M1 is connected to the first power supply end, the drain of the RF switch M1 is connected to the input end, the capacitor C1 is connected in series between the source and the output port of the RF switch M1, the drain of the RF switch M2 is connected in parallel between the mutual coupling inductor L1 and the mutual coupling inductor L2 of the all-pass network structure, the gate of the RF switch M2 is connected to the first power supply end, the source of the RF switch M2 is connected to the drain of the RF switch M3, a resonant network is connected to the drain and source of the RF switch M3, and the gate of the RF switch M3 is connected to the second power supply end.

[0048] In order to improve the standing wave of the entire phase shift circuit, the resonant network includes an inductor L3 and a capacitor C4, one end of the inductor L3 is connected in parallel between the source of the RF switch M2 and the drain of the RF switch M3, and the other end is grounded, one end of the capacitor C4 is connected to the source of the RF switch M3, and the other end is grounded. The gates of the RF switches M1, M2, and M3 are all connected to the power supply terminal through gate resistors.

[0049] Based on Figure 1 As shown in the circuit diagram, the working principle of the circuit is:

[0050] In the reference state, the switch tubes M1 and M2 are closed, and M3 is open. At this time, the phase change and insertion loss of the signal transmission are very small. In this state, the on-resistance of M1 determines the insertion loss of the phase shifter. Usually, large-size tube core parameters are selected to achieve low insertion loss characteristics;

[0051] In the phase shift state, switches M1 and M2 are open and M3 is closed. The amplitude difference between the phase shift state and the reference state can be adjusted by adjusting the size of M2, thereby reducing the parasitic amplitude modulation of the phase shifter.

[0052] In this embodiment, in order to obtain a larger working bandwidth, the two mutually coupled inductors of the all-pass network structure are reversely wound and a negative coupling coefficient is used, thereby improving the phase shift bandwidth of the entire circuit structure.

[0053] Example 2

[0054] This embodiment is based on the ultra-wideband small phase shift digital phase shift circuit of embodiment 1, and draws the following Figure 2 The design process of the circuit layout shown is:

[0055] S1. Draw a layout of a full-pass network structure in the simulation software, and generate a symbol of a full-pass network element from the drawn full-pass network structure and store it in a PDK element library of the simulation software;

[0056] The method for drawing the full-pass network structure is: equating the mutual coupling inductor L1 and the mutual coupling inductor L2 to square inductors, drawing the mutual coupling inductor L1 and the mutual coupling inductor L2 as a two-port transformer network structure, storing the drawn transformer network structure in a graphic template of the full-pass network element, and recording the element parameters drawn at this time; the element parameters include: order, inner circle width, inner circle size and spacing.

[0057] The graphic template of the all-pass network element and its corresponding element parameters are assembled into a symbol of the all-pass network element and stored in the PDK element library.

[0058] S2. Call the corresponding components in the ultra-wideband small phase-shift digital phase-shift circuit and the generated symbol of the full-network structure from the PDK component library, and draw the corresponding simulation schematic diagram of each component according to the ultra-wideband small phase-shift digital phase-shift circuit; when drawing the simulation schematic diagram, the inductor L3 is equivalent to an octagonal spiral inductor.

[0059] S3, setting parameters of each component in the simulation schematic diagram, simulating the simulation schematic diagram, and obtaining corresponding actual simulation results;

[0060] S4, judging whether the actual simulation result reaches the preset simulation result, if not, repeating steps S1-S4 until the preset simulation structure is reached, and obtaining the simulation parameters of each component;

[0061] S5. Convert each component into a component required by the MMIC circuit layout according to the corresponding simulation parameters.

[0062] According to the above method, this embodiment provides a set of specific parameters. In the layout, the substrate adopts a 0.25um GaAs process. It is assumed that the designed phase shift is 11.25 degrees, and the MMIC RF switches (M1-M3) are 6*55um, 10*85um, and 2*25um. The number of turns of the octagonal spiral inductor L3 is 10.75 turns, the width is 7um, the spacing is 4um, and the diameter is 35um; the stack MIM capacitor C1 is 110um*80um, and the MIM capacitor C4 is 80um*90um; the gate resistor Rg is folded to reduce the layout area of ​​the resistor, and the all-pass network structure is designed as a first-order all-pass network structure. The simulation schematic diagram obtained after simulation is as follows: Figure 3-Figure 5 As shown, from Figure 5 (a) It can be seen that the phase shift of the phase shifter designed according to the above parameters is between 11.15 degrees and 11.35 degrees. Figure 5 (b) It can be seen that the phase shift accuracy is less than ±0.2°. Figure 4 (b) shows that the insertion loss is less than 0.4dB. Figure 4 (a) It can be seen that the insertion loss fluctuation IL_Error < ±0.08dB, such as Figure 3 As shown in (a), the input echo (S11, S22) is less than -17dB, such as Figure 3 As shown in (b), the output echo (S33, S44) is less than -20dB.

[0063] In order to better illustrate that the phase shifter provided in this embodiment has improved performance in various aspects compared with the existing structural design, such as Figure 6 As shown in the figure, a simulation schematic diagram of a digital phase shift circuit with ultra-wideband and small phase shift realized by an all-pass structure is given. It can be seen that the circuit structure is huge, and the circuit structure produced cannot be miniaturized. Figure 7 As shown in (a)-(b), the return loss (S11, S22, S33, S44) is less than 15dB at 2GHz-7GHz. Figure 8 As shown in (b), its insertion loss is less than 2.7dB. Figure 8 As shown in (a), the insertion loss fluctuation IL_Error is less than ±0.25dB. Fig. 9 As shown in (a), the phase shift accuracy is less than ±0.4°. Fig. 9 As shown in (b), the phase shift is 10.9-11.55 degrees. Fig.10 As shown in the figure, the simulation diagram of the ultra-wideband small phase shift digital phase shift circuit using a bridge T-type structure is shown in the figure. The simulation results at 2GHz-7GHz are as follows: Figure 11-13 As shown, specifically, Fig.11 As shown in (a)-(b), the return loss (S11, S22, S33, S44) is less than 18dB. Fig.12 As shown in (b), the insertion loss is less than 0.6dB; Fig.12 As shown in (a), the insertion loss fluctuation is less than ±0.25dB; Fig.13 (a) shows that the phase shift is 10.1-12.4 degrees. Fig.13 As shown in (b), its phase shift accuracy is less than ±1.2°. The performance comparison of the three structures at the same bandwidth is shown in Table 1:

[0064] Table 1 Index comparison table

[0065]

[0066] It can be seen that this embodiment adopts the method of embedding the all-pass network structure into the bridge T-type network, which ensures bandwidth expansion while also ensuring high phase shift accuracy.

[0067] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. An ultra-wideband small phase shift digital phase shift circuit, characterized in that: The ultra-wideband phase-shifting network includes a bridge T-type network embedded with an all-pass network structure, and the all-pass network structure is a dual-port transformer network wound with two mutually coupled inductors. It also includes an input port and an output port, and the all-pass network structure includes a mutual coupling inductor L1, a mutual coupling inductor L2, a capacitor C2 and a capacitor C3, wherein the capacitor C2 is connected in series between the input port and the output port, one end of the mutual coupling inductor L1 is connected to one end of the mutual coupling inductor L2, the other end of the mutual coupling inductor L1 is connected in parallel to the input port, the other end of the mutual coupling inductor L2 is connected in parallel to the output port, and a capacitor C3 connected to the ground is connected in parallel between the mutual coupling inductor L1 and the mutual coupling inductor L2; The bridge T-type network includes an all-pass network structure, an RF switch M1, an RF switch M2, an RF switch M3, a capacitor C1, and a resonant network. The gate of the RF switch M1 is connected to the first power supply end, the drain of the RF switch M1 is connected to the input end, the capacitor C1 is connected in series between the source and the output port of the RF switch M1, the drain of the RF switch M2 is connected in parallel between the mutual coupling inductor L1 and the mutual coupling inductor L2 of the all-pass network structure, the gate of the RF switch M2 is connected to the first power supply end, the source of the RF switch M2 is connected to the drain of the RF switch M3, a resonant network is connected to the drain and source of the RF switch M3, and the gate of the RF switch M3 is connected to the second power supply end.

2. The ultra-wideband small phase shift digital phase shift circuit according to claim 1, characterized in that: The resonant network includes an inductor L3 and a capacitor C4. One end of the inductor L3 is connected in parallel between the source of the RF switch M2 and the drain of the RF switch M3, and the other end is grounded. One end of the capacitor C4 is connected to the source of the RF switch M3, and the other end is grounded.

3. A simulation method based on the ultra-wideband small phase shift digital phase shift circuit as claimed in claim 1, characterized in that: The following steps are involved: S1. Draw a layout of a full-pass network structure in the simulation software, and generate a symbol of a full-pass network element from the drawn full-pass network structure and store it in a PDK element library of the simulation software; S2, calling the corresponding components in the ultra-wideband small phase shift digital phase shift circuit as claimed in claim 1 and the generated full network structure symbol from the PDK component library, and drawing the corresponding simulation schematic diagram of each component according to the ultra-wideband small phase shift digital phase shift circuit; S3, setting parameters of each component in the simulation schematic diagram, simulating the simulation schematic diagram, and obtaining corresponding actual simulation results; S4, judging whether the actual simulation result reaches the preset simulation result, if not, repeating steps S1-S4 until the preset simulation structure is reached, and obtaining the simulation parameters of each component; S5. Convert each component into a component required by the MMIC circuit layout according to the corresponding simulation parameters.

4. The simulation method according to claim 3, characterized in that: The method for drawing the full-pass network structure is: the mutual coupling inductor L1 and the mutual coupling inductor L2 are equivalent to square inductors, the mutual coupling inductor L1 and the mutual coupling inductor L2 are drawn as a two-port transformer network structure, the drawn transformer network structure is stored in a graphic template of the full-pass network element, and the element parameters drawn at this time are recorded; The graphic template of the all-pass network element and its corresponding element parameters are assembled into a symbol of the all-pass network element and stored in the PDK element library.

5. The simulation method according to claim 4, characterized in that: Component parameters include: order, inner circle width, inner circle size, and spacing.

6. The simulation method according to claim 3, characterized in that: When drawing the simulation schematic, the inductor L3 is equivalent to an octagonal spiral inductor.

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