A CMOS Norton amplifier-based digitally controlled VGA forlow-power wireless applications

摘要

A CMOS variable-gain amplifier (VGA) for use in the basebandnsection of integrated wireless receivers is presented. The VGA circuitnis based on a new CMOS realization of the Norton transresistancenamplifier. The proposed CMOS realization operates from a 3-V supplynvoltage with rail-to-rail swing and class AB input and output stages.nThe standby current of the class AB stages employed can be accuratelyncontrolled, leading to a low power consumption, nonslew-rate-limitednresponse. The VGA circuit provides a precise process-independent gainncontrol range of 30 dB with 1-dB gain step. The circuit uses currentndivision techniques to provide an area-efficient 6-bit digital offsetntrimming capability. Experimental results from a test chip fabricatednthrough MOSIS are provided