A 0.2–6GHz 65nm CMOS Active-Feedback LNA with Threefold Balun-Error Correction and Implicit Post-Distortion Technique

We propose a wideband low-noise amplifier (LNA) with balun-error correction and linearity enhancement. Towards active feedback LNA in double CS stages, a threefold correction of voltage ratio preset, differential current balancer (DCB), and high-frequency RC compensation is applied to lower balun error across the passband. A linearization structure without penalty of add-on parasitic and noise is proposed herein. The active feedback path is reused as post-linearization to tap and cancel distortion of input CS stages at the LNA outputs. The distortion of the active load is regulated by tuning the output CM level via a CMFB block, to compensate for the residual distortion offset. A CM-DM noise conversion through asymmetry of output resistance is suppressed by the OTA filtering. Measurement results show that within the bandwidth of 0.2–6 GHz, the LNA prototype implemented in standard 65 nm CMOS technology, achieves a gain of 19.5 dB, a noise figure (NF) of 2.8 dB. Across the passband, gain and phase errors are within 0.5 dB and 1° while the average IIP3 reaches 2.5 dBm. The proposed circuit consumes 14.7 mW and occupies core area of 0.095 mm².