High performance millimeter wave active vector combining phase shifter

Abstract

The application discloses a high-performance millimeter wave active vector synthesis phase shifter, which sequentially comprises an input matching amplification circuit, a quadrature coupler, two inter-stage processing circuits, a vector synthesizer and an output matching circuit; the input matching amplification circuit is used for realizing impedance matching, DC isolation and power amplification of an input signal; the quadrature coupler is used for converting the input signal into an output signal with a phase difference of 90 degrees; the inter-stage processing circuit is used for amplifying, noise-reducing and phase adjusting two signals with a phase difference of 90 degrees; the vector synthesizer is used for vector synthesizing the two signals processed by the inter-stage processing circuit; and the output matching circuit is used for realizing impedance matching of the output signal. The application not only realizes optimization of loss, phase error and gain error, but also has the characteristics of large bandwidth, high precision and high integration.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of phase shifters, in particular to a high-performance millimeter wave active vector synthesis phase shifter. BACKGROUND

[0002] The phase shifter is a key module in the phased array radar, is the main element of controlling and changing the phase shift of electromagnetic waves, and can realize beam scanning and beamforming. In recent years, as the spectrum resources of low frequency band become increasingly tense, people's vision gradually converges on the millimeter wave frequency band (30GHz-300GHz), so the millimeter wave phased array becomes a hot research field at home and abroad. The millimeter wave wireless communication system has the characteristics of large bandwidth and maximum transmission power, and can realize high-speed wireless data communication at a rate of several Gbps. Therefore, it is of great significance to study the millimeter wave chip applied to the 60GHz communication system.

[0003] The phase shifter can be divided into passive and active structures according to the structure. The passive structure includes switched inductor-capacitor phase shifter, reflective phase shifter and loaded phase shifter. These passive structures usually have high linearity performance, but also have the disadvantages of high loss, high noise and large area on the chip. The active structure such as vector synthesis phase shifter usually shows higher gain, smaller chip area and higher phase shift resolution than the passive phase shifter.

[0004] In order to solve the problems of large area, large loss of passive structure and low precision and large root mean square phase error of traditional active structure, the present application designs a millimeter wave active vector synthesis phase shifter based on transformer. SUMMARY

[0005] The purpose of the present application is to provide a high-performance millimeter wave active vector synthesis phase shifter, which can not only realize the optimization of loss, phase error and gain error, but also has the characteristics of large bandwidth, high precision and high integration.

[0006] To solve the above technical problems, the present application provides a high-performance millimeter wave active vector synthesis phase shifter, which comprises an input matching and amplification circuit, a quadrature coupler, two inter-stage processing circuits, a vector synthesizer and an output matching circuit in sequence.

[0007] The input matching and amplification circuit is used for realizing impedance matching, DC isolation and power amplification of the input signal.

[0008] The quadrature coupler is used for converting the input signal into an output signal with a phase difference of 90°.

[0009] The inter-stage processing circuit is used for amplifying, noise reducing and phase adjusting the two signals with a phase difference of 90°.

[0010] A vector combiner is used to combine two signals processed by the inter-stage processing.

[0011] An output matching circuit is used to match the impedance of the output signal.

[0012] Further, the input matching amplifier circuit comprises an input matching transformer, and the input matching transformer is connected with a front-end amplifier.

[0013] Further, the amplifier adopts a differential common-source power amplifier structure.

[0014] Further, the quadrature coupler adopts a transformer-based full-differential quadrature signal coupler.

[0015] Further, the inter-stage processing circuit comprises an inter-stage matching transformer, an inter-stage amplifier, a series resonant transformer, a digital-to-analog converter and a digital decoder connected between two of the digital-to-analog converters.

[0016] Further, the digital-to-analog converter comprises the same I and Q paths, and the digital-to-analog converter adopts a plurality of differential switch transistors in parallel.

[0017] Compared with the prior art, the present application has at least the following beneficial effects:

[0018] (1) The present application adopts a two-stage amplification active vector combination phase shifter structure. The bias voltage of the amplifier can be adjusted to flexibly realize the compromise optimization between power consumption, loss and linearity parameter indexes. In addition, the resonant transformer is inserted between the second-stage amplifier and the digital-to-analog converter, which can be resonated with the parasitic capacitances of the front and rear stages, thereby greatly improving the bandwidth of the phase shifter.

[0019] (2) The present application adopts a cooperative working mode between the 6-bit digital decoder and the digital-to-analog converter, so that a 360-degree scanning range and a 6-bit scanning accuracy can be realized without the need of an external reference, and a low root mean square phase error of 0.7 degrees and a gain error of 0.35 dB are realized at 60 GHz.

[0020] (3) The present application adopts a wideband low-loss small signal quadrature coupler, which fully utilizes the process metal layer options, adopts the top four metal layers for layout, combines the upper and lower couplings and the side couplings, and reasonably arranges four inductors to only occupy the area of one inductor, thereby greatly reducing the overall chip area. By making the metal layers more compact, the coupling coefficient of the transformer is increased, and the loss is reduced. The signal propagation is realized through magnetic coupling, which can ensure that the output can meet the quadrature requirement under a wide band. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1Circuit structure schematic diagram of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0022] Figure 2 Model diagram of the input matching transformer of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0023] Figure 3 Circuit structure schematic diagram of the differential common-source power amplifier of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0024] Figure 4 Structure schematic diagram of the traditional quadrature signal coupler;

[0025] Figure 5 Lumped circuit diagram of the quadrature signal coupler of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0026] Figure 6 Model diagram of the quadrature signal coupler of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0027] Figure 7 Phase simulation result diagram of the quadrature signal coupler of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0028] Figure 8 Gain simulation result diagram of the quadrature signal coupler of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0029] Figure 9 Model diagram of the inter-stage matching transformer of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0030] Figure 10 Model diagram of the series resonance transformer of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0031] Figure 11 Model diagram of the digital-to-analog converter of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0032] Figure 12 Model diagram of the phase shifter output matching transformer of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0033] Figure 13 Phase simulation diagram of the 6bit phase shifter of an embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the present application;

[0034] Figure 14The simulation diagram of the root mean square phase error of the 6bit phase shifter of one embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the application;

[0035] Figure 15 The simulation diagram of the small signal gain S21 of the 6bit phase shifter of one embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the application;

[0036] Figure 16 The simulation diagram of the root mean square gain error of the small signal gain S21 of the 6bit phase shifter of one embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the application;

[0037] Figure 17 The simulation diagram of the input-output return loss S11 of the 6bit phase shifter of one embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the application;

[0038] Figure 18 The simulation diagram of the input-output return loss S22 of the 6bit phase shifter of one embodiment of the high-performance millimeter wave active vector synthesis phase shifter of the application. DETAILED DESCRIPTION

[0039] The high-performance millimeter wave active vector synthesis phase shifter of the application will be described in more detail below with reference to the accompanying drawings, in which the preferred embodiments of the application are shown, it should be understood that those skilled in the art can modify the application described herein while still achieving the advantageous effects of the application. Therefore, the following description should be understood as a broad knowledge for those skilled in the art, and not as a limitation on the application.

[0040] The application will be described in more detail in the following paragraphs with reference to the accompanying drawings. The advantages and features of the application will be more apparent from the following description and claims. It should be noted that the drawings are very simplified and all use non-precise proportions, only to facilitate, clearly assist in the purpose of illustrating the embodiments of the application.

[0041] As shown in Figure 1 , the embodiment of the application proposes a high-performance millimeter wave active vector synthesis phase shifter, which sequentially comprises an input matching amplification circuit, a quadrature coupler, two inter-stage processing circuits, a vector synthesizer and an output matching circuit;

[0042] The input matching amplification circuit is used to realize impedance matching, DC isolation and power amplification of the input signal;

[0043] The quadrature coupler is used to convert the input signal into an output signal with a phase difference of 90°;

[0044] The inter-stage processing circuit is used to amplify, denoise and phase adjust the two signals with a phase difference of 90°;

[0045] a vector combiner for vector combining the two signals after inter-stage processing;

[0046] an output matching circuit for realizing impedance matching of the output signal.

[0047] In the embodiment, the application designs a transformer-based millimeter wave 60GHz 6bit active vector combining phase shifter, which is improved on the basis of the traditional active phase shifter architecture, and uses on-chip transformers to realize all matching networks. The transformer can realize the functions of impedance matching and DC isolation at the same time, and the matching transformer has the advantages of small size, no need for DC blocking capacitor, power supply through center tap, transmission of differential signal, etc. Compared with the traditional inductance-capacitance network for impedance matching, the use of transformer matching can realize greater design freedom with the equivalent area of inductance, while reducing the loss of the matching network; compared with the use of microstrip line for inter-stage matching, the chip area can be miniaturized.

[0048] The following lists the preferred embodiments of the high-performance millimeter wave active vector combining phase shifter to clearly illustrate the content of the application. It should be clear that the content of the application is not limited to the following embodiments, and other improvements by the conventional technical means of ordinary skilled in the art are also within the scope of the idea of the application.

[0049] The input matching amplifier circuit includes an input matching transformer, and the output end of the input matching transformer is connected with a front-end amplifier.

[0050] Specifically, the input matching transformer is implemented by 3D modeling using HFSS and electromagnetic simulation is completed. The final electromagnetic simulation diagram is as shown in Figure 2 The transformer is composed of upper and lower two octagonal inductors, and the lower inductor is hollowed out to increase the quality factor of the inductor and reduce the loss. The lower inductor adopts a two-turn structure to increase the coupling coefficient with the upper inductor, and the intersection is connected with low-layer metal and the center tap is led out with the low-layer metal. The center tap is led out from the left and right sides to increase the symmetry of the transformer and serve as a DC supply port.

[0051] The amplifier adopts a differential common-source power amplifier structure.

[0052] Specifically, in comparison, the common-source common-gate structure needs higher power supply voltage, while the differential common-source structure can realize higher voltage swing and can use lower power supply voltage. The amplifier is composed of an input tube M and a neutralizing capacitor CN. The main function of the neutralizing capacitor is to increase the gain and stability. The size of the input transistor M adopts the largest gate index to minimize the parasitic capacitance between the gate and the drain, thereby optimizing the high-frequency performance of the circuit. A suitable width can obtain a good current density and a smaller gate resistance, thereby maximizing the efficiency. The smaller the gate length allowed by the CMOS process, the higher the characteristic frequency of the transistor, and the better the high-frequency performance. By selecting the appropriate transistor size, the power amplifier realizes the maximum current density, thereby realizing the maximum power gain. As shown in Figure 3 .

[0053] The quadrature coupler adopts a transformer-based fully differential quadrature signal coupler.

[0054] Specifically, the traditional quadrature signal coupler, as shown in Figure 4 , is composed of two λ / 4 transmission lines, and the coupling coefficient is fixed at 0.707. Due to the use of λ / 4, the quadrature coupler has a very large area, which is not conducive to on-chip implementation of silicon-based CMOS, and only achieves complete quadrature at a single frequency point, so the bandwidth is limited and is not conducive to wideband applications.

[0055] The present application is designed as a transformer-based fully differential integrated quadrature signal coupler with small area, low loss, large bandwidth and adjustable coupling coefficient. As shown in Figure 5 , is its lumped model, in which ISO+ represents the isolation end, connected through a 100-ohm resistor. THU+, THU- represent the in-phase end, CPL+, CPL- represent the quadrature end, IN+, IN- represent the input signal end, and Cp represents the parasitic capacitance. The physical layout of the quadrature signal coupler is shown in Figure 6 , which uses the upper four layers of metal for layout, and two transformers are arranged into an inductor area through reasonable layout, greatly reducing the chip area and increasing the coupling coefficient of the transformer, thereby reducing the loss. Signals are transmitted through magnetic coupling and achieve output phase quadrature.

[0056] Figure 7 , 8 is the phase and gain simulation results of the quadrature signal coupler. It can be seen that within 55GHz-65GHz, the phase quadrature characteristic is good, which is conducive to wideband applications. The gain characteristic diagram has only 0.65dB (3dB is power separation) insertion loss at 60GHz. Therefore, the quadrature coupler realizes good performance indicators.

[0057] The inter-stage processing circuit comprises an inter-stage matching transformer, an inter-stage amplifier, a series resonant transformer, a digital-to-analog converter and a digital decoder connected between two of the digital-to-analog converters in sequence.

[0058] Specifically, the design of the inter-stage matching transformer is as shown in Figure 9 The specific layout implementation is similar to the input matching transformer. In addition, the light green metal aluminum layer also leads the center tap to provide a DC port.

[0059] Specifically, the series resonant transformer is as shown in Figure 10 The 3-turn compact inductor is used for signal transmission through sidewall coupling.

[0060] Specifically, the digital-to-analog converter is composed of the same I and Q paths, adopts a plurality of differential switch transistors in parallel structure, and the transistor parallel size adopts the optimal ratio of 1:2:4:8:16:32, as shown in Figure 11 The digital signals 0 and 1 output by the 6-bit digital decoder represent the lowest potential GND and the highest potential VDD of the chip, and the output signals control the gates of all the transistors of the digital-to-analog converter, when the gate voltage is GND, the transistor is closed; when the gate voltage is VDD, the transistor is opened; therefore, by reasonably selecting the transistor size of the digital-to-analog converter and the control mode of the 6-bit digital decoder, the phase shift range from 0 degrees to 360 degrees can be realized, and the phase accuracy of 6 bits.

[0061] Specifically, as shown in Figure 12 The output matching transformer is similar to the input matching transformer, and since the inductance value required is small, only one turn of the upper and lower inductors is needed.

[0062] After the circuit design is completed, the schematic simulation is completed by the Cadance Virtuoso software, the passive structure in the circuit and the key connection are all designed by 3D modeling and parameter extraction by the electromagnetic simulation software Ansys HFSS. The simulation analysis results are as follows:

[0063] (1) Figure 13 and Figure 14 are the phase simulation diagram and the root mean square phase error simulation diagram of the 6-bit phase shifter, the 360-degree phase shift range and the 6-bit accuracy are realized, and the lowest root mean square phase error is only 0.7 degrees.

[0064] (2) Figure 15 and 16 are the small signal gain S21 simulation diagram and the root mean square gain error simulation diagram of the 6-bit phase shifter, the gain range realized by the present application is-2.8dB to-1.3dB, and the lowest root mean square gain error is only 0.35 degrees.

[0065] (3) Figure 17 and 18 are the input and output return loss S11, S22 simulation graphs of 6bit phase shifter. At 60GHz, the return loss of the present application can achieve below-10dB.

[0066] In summary, compared with the traditional vector synthesis phase shifter, the present application has at least the following beneficial effects:

[0067] (1) The present application adopts two-stage amplification active vector synthesis phase shifter structure. The bias voltage of the amplifier can be adjusted to flexibly realize the optimization between power consumption, loss, linearity parameter indicators. In addition, the resonant transformer is inserted between the second-stage amplifier and the digital-to-analog converter, which can be resonated with the parasitic capacitance of the front and rear stages, thereby greatly improving the bandwidth of the phase shifter.

[0068] (2) The present application adopts the cooperative working mode between 6bit digital decoder and digital-to-analog converter, so that the scanning range of 360 degrees, the scanning accuracy of 6bit and the root mean square phase error of as low as 0.7 degrees and the gain error of 0.35dB at about 60.5GHz can be realized without the need of external reference.

[0069] (3) The present application adopts a wideband low-loss small signal quadrature coupler, which fully utilizes the process metal layer options, adopts the top four metal layers for layout, combines the upper and lower coupling and the side coupling, and through reasonable layout of four inductors, it only occupies the area of one inductor, greatly reducing the overall chip area. And by making the metal layers more compact, the coupling coefficient of the transformer is increased, and the loss is reduced. Through magnetic coupling for signal propagation, it can ensure that the output can meet the quadrature requirement under wideband.

[0070] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A high performance millimeter wave active vector combining phase shifter, characterized by, The input matching amplification circuit, the quadrature coupler, the two-way inter-stage processing circuit, the vector synthesizer and the output matching circuit are sequentially arranged; The input matching amplification circuit is used for realizing impedance matching, DC isolation and power amplification of the input signal; The input matching amplification circuit comprises an input matching transformer; The quadrature coupler is used for converting the input signal into an output signal with a phase difference of 90°; The inter-stage processing circuit is used for amplifying, noise reducing and phase adjusting the two-way signals with a phase difference of 90°; The vector synthesizer is used for vector synthesizing the two-way signals after the inter-stage processing; The output matching circuit is used for realizing impedance matching of the output signal. The quadrature coupler adopts a transformer-based full-differential quadrature signal coupler, and the full-differential quadrature signal coupler is based on transformer-based full-differential integration.

2. The high performance millimeter-wave active vector combining phase shifter of claim 1, wherein, The input matching transformer is connected with a front-end amplifier.

3. The high performance millimeter-wave active vector combining phase shifter of claim 2, wherein, The amplifier adopts a differential common-source power amplifier structure.

4. The high performance millimeter-wave active vector combining phase shifter of claim 1, wherein, The quadrature coupler adopts a transformer-based full-differential quadrature signal coupler.

5. The high performance millimeter-wave active vector combining phase shifter of claim 1, wherein, The inter-stage processing circuit comprises an inter-stage matching transformer, an inter-stage amplifier, a series resonant transformer, a digital-to-analog converter and a digital decoder connected between two digital-to-analog converters.

6. The high performance millimeter-wave active vector combining phase shifter of claim 5, wherein, The digital-to-analog converter comprises the same I and Q paths, and the digital-to-analog converter adopts a plurality of differential switch transistors in parallel structure.

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