15GHz 線性化射頻功率控制系統

Abstract

本論文將介紹15GHz線性化通訊發射機功率控制系統。其架構功能不同於現有的通訊電路將RF Attenuation、linearizer分開，而採用控制輸出級PHEMT device的閘極直流偏壓，利用不同的工作點改變其增益，相較於一般只有20dB用PIN Diode設計的反射式衰減器，其 power control dynamic range可達到40dB。並利用控制放大器閘極電壓來補償因較大的訊號輸入power amplifier時所造成的非線性失真，在大功率輸出時其非線性的互調失真仍可有3dBc的改善。

This thesis illustrates the 15GHz linear RF power control system. The architecture is distinct from the circuit that RF attenuation and linearizer are separated. I control the gate DC voltage of output PHEMT device to change the gain by different bias point. The dynamic range can reach the 40dB compared with the only 20dB reflecting pin diode attenuator. It is used to control the gate voltage to compensate the nonlinear distortion when large signal input the power amplifier. The improvement of 3dBc inter-modulation have been achieved.