A CMOS active feedback wideband single-to-differential LNA using inductive shunt-peaking for saw-less SDR receivers

A wideband active feedback single-to-differential (S-to-D) LNA composed of a S-to-D converter, a voltage combiner, and a negative feedback network is proposed. By feeding the single-ended output of the voltage combiner, which is used for combining the differential output of the S-to-D converter, to the input of the LNA through the feedback network, a wideband S-to-D LNA exploiting negative feedback is implemented. By using shunt-peaking of the source follower (SF) based active inductor, the proposed S-to-D LNA can achieve wider loop gain bandwidth with balun functionality. The 3-dB gain bandwidth of the proposed S-to-D LNA is above 5 GHz and the NF is below 4 dB from 100 MHz to 5 GHz. An average voltage gain of 18 dB and an IIP3 of -5 dBm are obtained.