| Next-generation mobile communication network will face enormous challenges,such as ultra-low latency,ultra-high data rates and ultra-high connection density.Terahertz communication system can be used in next-generation mobile communication system to meet the needs of higher data rates and wider service range.Terahertz power amplifier,as an important part of communication system,has been widely concerned and studied by scholars around the world.Indium phosphide double heterojunction bipolar transistor(InP DHBT)has become a mainstream device for the terahertz power amplifier with its excellent performance.The domestic research about terahertz InP power amplifier is still in the exploration phase.In this thesis,terahertz power amplifier is studied using the domestic 0.25 μm InP DHBT devices.This thesis is organized as follows:1.Research on the design essentials of terahertz InP DHBT power amplifier.Based on the InP DHBT process provided by Nanjing Institute of Electronic Devices(NEDI),the routing scheme and design steps of terahertz power amplifier are studied,which lays a foundation for the further research and design of terahertz InP DHBT power amplifier.2.Design of 220 GHz four-stage and four-way power amplifier.Based on the transmission line theory,a four-way power combiner is designed,which achieves impedance matching with low loss(transmission loss at the center frequency is 0.89 d B).The co-simulation results of the four-stage four-way power amplifier show that the small signal gain is 18.1 d B,the saturated output power is 16.1 d Bm,and the power gain is 11.1d B,the power additional efficiency is 10.0 %.When the gain is compressed by 3 d B,the output power is 13.8 d Bm and the power additional efficiency is 7.7 %.3.Design of 220 GHz balanced power amplifier.The impedance matching of input and output ports of the 4-way 4-stage power amplifier is always unsatisfactory.Explored the design scheme of terahertz quadrature coupler circuit in NEDI’s InP process.And a balanced power amplifier is designed using a 220 GHz quadrature coupler.Compared with the four-stage four-way power amplifier,the output port of this balanced power amplifier is well matched from 200 to 240 GHz.The co-simulation results of the balanced power amplifier show that the small signal gain is 9.0 d B,the saturated output power is13.1 d Bm,and the power gain is 7.1 d B.When the gain is compressed by 1 d B,the output power is 12.6 d Bm and the power additional efficiency is 7.6 %.4.Verification of 220 GHz Doherty power amplifier.For current terahertz InP DHBT power amplifiers,Class A is the most common bias condition.In order to improve the efficiency of Terahertz InP DHBT power amplifier at output back-off(OBO)region,a load modulation network for terahertz InP power amplifier is proposed by combining the classical Doherty power amplifier structure with the common power combiner network of terahertz InP power amplifier.And a 220 GHz Doherty power amplifier is designed.The schematic simulation results show that at 6 d B OBO,compared with Class A and Class B power amplifiers,the power additional efficiency is increased by 2.5 times and1.2 times,respectively. |
