A Programmable Gain Amplifier with Fast Transient Response for Medical Ultrasound System

Abstract

This paper presents a programmable gain amplifier (PGA) with fast transient response for medical ultrasound system. In this real-time gain control of PGA, image artifacts can occur during transient gain-switching period. To sufficiently reduce a transient period due to gain switching of PGA, this work proposes a preset scheme of capacitors and a single-stage push-pull amplifier. The preset scheme can preliminarily set the operating points for capacitors during TX phase of system, so operating point fluctuation during gain switching is minimized. In addition, a fast recovery can be achieved by adopting the flipped voltage follower based push-pull amplifier. The proposed PGA was designed in 180-nm BCD process with an active area of 0.0371 mm(2). The PGA operates at a supply voltage of 1.8V and its power consumption is 1.1 mW. The simulated gain range is [0, 30] dB. The simulated transient period during gain switching is less than 2 ns.