自适应偏置的低噪声放大器设计与实现

Design and Implementation of Self-Adapting-Bias Low Noise Amplifier

低噪声放大器作为射频接收系统中的关键器件,其噪声系数与线性度影响整个系统的性能。本文基于0.25μm GaAs pHEMT工艺设计了一款应用于DC~3 GHz的低噪声放大器。放大器采用耗尽型晶体管构成自适应偏置电路提升低噪声放大器线性度,通过源极高Q值电感优化噪声系数。该低噪声放大器芯片的测试结果表明,与传统偏置结构的放大器相比,随着输入功率的增大,该电路具有良好的栅电压补偿功能,噪声系数比传统结构减小0.5 dB以上,相同工作电流下输出功率1 dB压缩点提高11 dB,相同射频输出功率下直流功耗减小40%以上。

Low Noise Amplifier(LNA)is a key component in RF receiving system,whose noise and linearity influences performance of the whole system.A low noise amplifier applied in DC~3 GHz is designed with self-adapting bias circuit consisting of depletion-mode pseudomorphic high electron mobility transistor(pHEMT)to improve linearity,and with high-quality-factor inductor to optimize noise factor,based on 0.25μm GaAs pHEMT process in this paper.The measurement results show outstanding gate voltage compensation function with the increase of the input power compared with the traditional LNA,the noise is reduced by more than 0.5 dB compared with the traditional LNA,the output power 1 dB compression point increased by 11 dB under the same working current,and the power consumption reduced by more than 40%under the same output RF power.