Research And Design Of Low Power Active Phase Shifter Based On Voltage Controlled Structure

In recent years,with the rapid development of wireless communication technology,active phased arrays are characterized by high reliability,short response time and strong anti-interference ability.Their research in related fields has not only been limited to military aspects,but also gradually turned to emerging industries such as 5G communication and unmanned driving.As an important module in the active phased arrays,the active phase shifter is used to control the phase relationship of signals between the antenna elements,the performance of which directly affects the whole system.Therefore,it is of great significance to develop a phase shifter with high performance,miniaturization and low cost.For this purpose,an active analog phase shifter is designed on the common C-X band using Si Ge Bi CMOS process with lower cost and better performance.The active analog phase shifter designed in this paper adopts the vector modulation method to change the phase and gain of the output signals under the external bias voltages.The main modules of the circuit include two-stage input active balun,synthetic network,compensation circuit and bandgap reference circuit.Moreover,the synthetic network consists of a quadrature signal generator and an analog adder.The two-stage input active balun is designed based on a noise cancellation structure,which can convert the single-ended input signal into a set of equal-amplitude differential signals and provide a certain gain for subsequent circuits.The differential output signals generated by the balun are vector superimposed in the synthetic network,achieving the phase shift of 0 to 360 under the condition that the bias voltages are continuously changed.In order to eliminate the insertion loss introduced by the passive module,the designed two-stage type-II quadrature signal generator is nested between the input transistor and the amplifier transistor of the analog adder,forming a nested synthetic network.The compensation circuit is a solution to the problem of the large gain error in the active analog phase shifter,which compresses the gain variation range by the current steering structure in order to reduce the gain error.In addition,the circuit plays the role of output balun,which can convert the differential output signals of the synthetic network into a single-ended output signal,and facilitates follow-up testing.The bandgap reference circuit is implemented by the principle of zero temperature coefficient,which can provide stable bias currents for the input balun and the compensation circuit in the phase shifter to ensure the normal operation of the whole circuit.The active analog phase shifter in this paper uses the Tower Jazz 0.18?m Si Ge Bi CMOS process and completes the overall circuit,layout design and simulation verification in Cadence software.The post simulation results show that the maximum power consumption of the phase shifter circuit is 89.1m W,and the maximum current is 27 m A under the supply voltage of 3.3V.Furthermore,the RMS phase error of the active analog phase shifter is less than 4.9,the RMS gain error is less than 2.2d B,the input reflection coefficient S11<-13.9d B,output reflection coefficient S22<-10.5d B,and the input 1d B compression point varies from-19.4d Bm to-14.6d Bm within the 4-12 GHz operating frequency.The performance indicators of the phase shifter meet the design requirements proposed in this paper and have the characteristics of low power consumption and high precision.