A Broadband CMOS Linear Variable Gain Low Noise Amplifier Design

This paper presents a 48 MHz ~860MHz broadband CMOS linear variable gain low noise amplifier (LNA) design. This LNA is combined with signal-summing structure, control signal converter and uses voltage-shunt negative feedback technique. The linear variable gain controlling, input wideband matching and noise optimization methods are analyzed in detail. The LNA is designed in TSMC 0.18μm RF CMOS technology, and achieves a linear logarithmic gain range of -5dB~18dB, a minimum noise figure of 2.9dB, S11 and S22 less than -10dB, input P1dB more than -14.5dBm, while consuming 45 mW from a 1.8 V power supply.