Wideband low noise variable gain amplifier

Abstract

A low noise variable gain amplifier (LNVGA) is fully designed for operation over a wideband. Since a low noise figure (NF) and a high 1 dB compression point (P1dB), i.e. large dynamic range, is difficult to achieve in CMOS technology, gain controllability is exploited to increase the overall system dynamic range. The LNVGA is composed by a low noise amplifier (LNA) stage and a voltage variable attenuator (VVA) stage. The former aims to keep the NF low, and the latter aims to provide a very large gain variation. Also, an output buffer is used to allow for measurement with 50 O probes. In addition, a novel Active Balun topology is proposed which achieves competitive results for magnitude imbalance and phase imbalance. The LNVGA simulation results show a gain control range of 47.7 dB, its voltage gain varies from -26.7 dB to 21 dB, the minimum NF is 3.43 dB, the IIP3 is -4.6 dBm, and a band of operation from 200 MHz to 3.5 GHz.