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 should be characterized by a wide gain variation range and low power consumption and noise. In this contribution, we propose an optimized VGA structure in CMOS technology for biomedical applications. The optimizations are performed at two levels: architectural and dimensional. For the architecture, the optimization is presented by the addition of a telescopic operational transconductance amplifier to the basic VGA cell in order to extend the gain variation range. As for the dimensional optimization: we develop an optimization algorithm, based on the heuristic maximization methodology, to adjust the optimal dimensioning of the different transistors of the VGA structure. Our proposal achieves considerable improvements over the existing characteristics of biomedical signal processing. Actually, 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.