A 40dB, 100MHz CMOS IF variable gain amplifier for DVB-C receivers

Abstract

A CMOS IF VGA used for DVB-C receivers is presented in this paper. The VGA core is based on current-steering structure, and several optimization methods are used to improve the linearity and stability. A novel CMOS exponential voltage generator is designed to realize the linear-in-dB control characteristic. The simulation results based on 0.25 mum CMOS process indicate that the VGA can provide 40dB gain control range, the IIP3 at the minimum gain setting 17.2 dBm, and the minimum NF 7.8 dB. The overall current dissipation is less than 23 mA at 3.3V supply voltage