A mixer-first receiver with a new transimpedance amplifier

A mixer-first receiver with high linearity and low noise is presented in this paper. Since there is no low noise amplifier (LNA) between the antenna and the mixer, the passive mixer reflecting the baseband impedance makes input impedance matching directly in the receiver. The choice of the operation amplifier (OTA) and the parasitic resistance of the passive mixer both decide the noise of the receiver, and the analysis and principle is shown in the paper. The mixer-first receiver here challenges a new structure of transimpedance amplifier (TIA), which consists of a g _m stage and a TIA stage. This new structure achieves low noise and high linearity. However, this new structure has the risk of stability, and the analysis about the stability is discussed in this paper. With the core circuit consuming 135mW, the prototype receiver implemented in 180nm CMOS technology achieves >20dB conversion gain, <;6dB in-band NF and >20dBm in-band IIP3 in 1.2GHz, with 1.8V supply.