一种紧凑型超宽带低噪声放大器研究

Research on a Compact Ultra-Wideband Low-Noise Amplifier

摘要:

针对高性能射频前端接收部分小型化的应用需求，基于0. 25 μm GaAs pHEMT工艺，设计了一款工作频率覆盖2 ~ 18 GHz的紧凑型超宽带低噪声放大器。放大器采用了两级级联电路拓扑，前级选用共源共栅结构配合源极串联电感负反馈，后级选用共源极结构，通过两级并联负反馈及紧凑型版图设计技术，优化了芯片的增益平坦度与面积，在噪声系数较小的同时拥有较大输出功率。经实验测试，芯片在2~18 GHz频带内实现了噪声系数≤2.8 dB，小信号增益22~26 dB且呈正斜率，输入驻波比<2.2，输出驻波比<2，输出功率1 dB压缩点>14 dBm。该器件尺寸仅为1 mm×1.5 mm，满足了宽频带、低噪声及小型化的工程应用需求。

Abstract:

To meet the de mand for miniaturization of high-performance RF front-end receivers, a compact ultra-wideband low-noise amplifier (LNA) whose working frequency covers 2-18 GHz is designed in a 0.25μm GaAs pHEMT process.The amplifier employs a two-stage cascaded architecture, the first stage adopts a cascode configuration to enhance high-frequency gain and utilizes source-series negative feedback of series inductor to achieve optimal noise matching, the second stage employs a common-source amplifier, thereby saving chip area while delivering high maximum output power. Both stages incorporate parallel negative feedback networks, resulting in a positive gain slope to the overall amplifier. In addition, the circuit is laid out in a compact form to minimize area. The results indicate that the LNA's Noise Figure (NF) is less than 2.8 dB across the 2–18 GHz broadband, and small-signal gain is 22-26 dB with a positive slope. The Output Voltage Standing Wave Ratio (VSWRout) is below 2, the Input VSWR (VSWRin) is below 2.2, and the 1 dB compression point (P1dB) is greater than 14 dBm. The chip size is 1 mm×1.5 mm, demonstrating the advantages of wide bandwidth, low noise, and small size.