0.8V bulk-driven variable gain amplifier

A low-voltage variable gain amplifier based on PMOS bulk-driven input stage is presented in this paper. The gain of the proposed amplifier has a linear in-dB gain dependency since it utilizes the conventional pseudo exponential approximation function (1+x)/(1-x). The master-slave technique is used in order to control the voltage gain. The amplifier is designed with a supply voltage of 0.8V featuring a gain range equal to 17dB with less than ±0.5dB linearity error. A standard 0.18μm CMOS process has been chosen to simulate and test the VGA topology confirming the theoretical analysis.