Design considerations for a low power variable gain amplifier for ultrasounds

This paper presents the simulation results and conclusions used to design a variable gain amplifier (VGA) for ultrasounds. It is defined the architecture and implementation of a VGA for a portable system with low power consumption and low noise for a frequency domain of 100 kHz to 4 MHz and a gain variation of 72 dB. The proposed circuit consists on a preamplifier, a switchable active filter and tree stages realized with current feedback amplifiers with variable gain. The circuit was analyzed by simulation to validate its parameters.