Determining the optimal number of gain stages of variable gain amplifiers used in multi-standard homodyne wireless receivers

This paper presents an analysis on determining the optimal number of gain stages of Variable Gain Amplifiers (VGAs) used in direct conversion CMOS multi-standard wireless receivers embedding analog baseband signal conditioning. In order to facilitate design porting, modern re-configurable wireless receivers are based on a modular architecture for the low frequency part of their analog signal conditioning chain, which includes also the VGA. The analysis constructed in this paper determines the optimal number of VGA stages as the solution of the trade-off between the stage amplifier´s power consumption and its linearity performance. Based on the presented analysis it results a VGA embedding 7 stages is able to achieve 84 dB gain range and it represents the best choice with respect to optimizing both the VGA power consumption and its linearity performance.