CMOS Low-Distortion High-Frequency Variable-Gain Amplifier

This paper describes the principle and design of a CMOS variable-gain amplifier for high-frequency applications. The operation of the differential circuit is based on a linear voltage-to-current conversion by means of a digitally controlled conversion impedance. Experimental results of the circuit show total harmonic distortion figures better than -60 dB and a gain accuracy of 0.05 dB over the -2 to + 12 dB gain range.