Improved derivative superposition scheme for simultaneous second- and third-order distortion cancellation in LNAs

An improved derivative superposition (IDS) scheme is examined for low-noise amplifier (LNA) linearisation, which utilises PMOS as an auxiliary FET in weak inversion for simultaneous second- and third-order distortion cancellation in wideband LNAs. The performance of a LNA with IDS is compared to that of a LNA with conventional derivative superposition (CDS) and common-source (CS) cascode LNA with the same power consumption. Simulation results show that the proposed LNA has nearly the same IIP₃ as the LNA by CDS linearisation and 7 dB improvement compared to the CS LNA. Further, it has more than 20 dB improvement in IIP₂. While the gain and noise figure of the proposed LNA are nearly unaffected, it only needs 0.2% extra power.