Design and analysis of CMOS low power variable gain amplifier for biomedical applications

This study falls within the radio frequency transmission of biomedical applications, where the variable gain amplifier (VGA) presents a key element since it adjusts the radio receiver performance. Due to the sensitivity of this field, the VGA must respect the imposed constraints. In this contribution, an optimized VGA structure in CMOS technology for biomedical applications is proposed. It realizes considerable improvements over the existing characteristics of biomedical signal processing by ensuring a wide dynamic range and low power topology and noise. The optimizations are performed at two levels; architectural and dimensional. For the architecture, the optimization is mainly presented by the addition of a telescopic operational transconductance amplifier and Common Mode Feedback circuit blocks to an optimized VGA cell in order to extend the gain variation range. As for the dimensional optimization, based on a heuristic maximization methodology, an optimization algorithm is developed to adjust the optimal dimensioning of the VGA structure that achieves significant performance improvements. In fact, it presents a reliable low power topology (consumption of 33.52 µW), which ensures a wide dynamic gain range that reaches 89.65 dB varying from − 19.72 dB to 69.93 dB.