Research On InP DHBT Devices In Mm-Wave Power Amplifier

In recent years,with the development of information technology and the increase of data volume transmitted,communication systems with higher data rate are needed.Coupled with the limited existing communication frequency band,there is a growing trend towards mm-wave research.There is a wide application for InP DHBT in mm-wave power amplifiers(PA)because of its high frequency,high linearity and large dynamic range.On the one hand,as frequency increases,the linearity requirements of PA increase,InP DHBT provides reliable device for high linearity PA;on the other hand,the requirements of complex modulation,multi-band and multi-function drive communication to.digitalization,and InP DHBT meet the design of high-speed digital-analog hybrid circuits such as digital PA(DPA)for its large dynamic range.This paper proves that InP DHBT device has excellent linearity through two-tone load-pull technology,which can meet the requirements of high linearity PA.On this basis,a K-band high linear PA based on InP DHBT process is developed.The adaptive linear current source is adopted to ensure the bias stability and temperature stability of PA under high power conditions,improve the linearity of the PA.At 26 GHz and 28 GHz,the measurement shows that IMD3 is less than-30 dBc at 2.5 dB power back-off.This PA meets the requirements of high linear PA in mm-wave transmitter.In addition,in response to digital development,an InP DHBT DPA is developed.Based on cascode structure,a two-stage cascode structure DPA cell is designed,which improves the gain of the DPA and switching ability.Eight DPA cells are connected in parallel,and digital signal controls the switch of each cell to realize modulation.At 20 GHz,the DPA demonstrates a PAE of 22.5%and output power of 23.5 dBm when the ACW is 8.However,the PAE decreases to 16%when the ACW is 4.In order to improve the efficiency at back-off state,back-off synthesis technology is proposed.When ACW is between 8 and 4,simulation results show that the PAE greater than 20%,which achieves the purpose of improving back-off efficiency.In addition,according to requirements of quadrature digital transmitter,three quadrature couplers with center frequency of 20 GHz are designed,and simulation results show good amplitude and phase error.The research of DPA and quadrature coupler will provide technical support for future digital transmitter.