Integrated front-end preamplifier dedicated to ultrasonic receivers

Abstract

This paper concerns the design and implementation of an integrated front-end preamplifier dedicated to ultrasonic receivers. A new preamplification technique composed of a logarithmic amplifier and followed by a programmable-gain amplifier is proposed. The logarithmic amplifier, based on a True Logarithmic Amplifier (TLA) technique, largely amplifies small amplitude signals, and moderately the large amplitude ones. The programmable-gain amplifier, based on Timing Gain Compensator (TGC), is used to compensate signal attenuation caused by its traveling several human body tissues. Spectre simulations of both the TLA and TGC show unity gain bandwidths of 100 MHz and 127 MHz respectively when driving a load of 1 pF. The implementation of this system (TLA, TGC) is done using CMOS 0.35 /spl mu/m technology. The total chip area is 7.2 mm/sup 2/ including the digital part needed to program the TGC.