A 2.8–3.8-GHz Reconfigurable GaAs Low-Noise Amplifier With Improved Blocker Tolerance

A reconfigurable low-noise amplifier (LNA) is proposed with integrated bandpass filter (BPF) responses covering 2.8–3.8 GHz in this letter. The proposed LNA consists of three cascaded transistor stages. By integrating the transformer-based second-order BPF into the interstage matching networks of the cascaded transistors, the blocker tolerance and linearity of the LNA can be significantly improved without sacrificing any additional chip area. To demonstrate the proposed technique, an LNA has been designed and fabricated in a 0.15- $\mu \text{m}$ GaAs process. The measured results show a maximum power gain of 35.5 dB and minimum noise figure (NF) of 1 dB with a stopband suppression of 43.5 dB. A blocker 1-dB compression point (B1dB) of −9 dBm is obtained at 4.25 GHz with LNA center frequency at 2.8 GHz and has been improved by at least 17 dB as compared to the in-band input 1-dB compression point (IP1dB). Good agreement between simulation and measurement is obtained.