A Low-Power Current-Reuse LNA for 3D Ultrasound Beamformers

Abstract

3D ultrasound imagers require low-noise amplifier (LNA) with much lower power consumption and smaller chip area than conventional 2D imagers because of the huge amount of transducer channels. This paper presents a low-power small-size LNA with a novel currentreuse circuitry for 3D ultrasound imaging systems. The proposed LNA is composed of a differential common source amplifier and a source-follower driver which share the current without using inductors. The LNA was fabricated in a 0.18-μm CMOS process with only 0.0056 mm2. The measured results show a gain of 21 dB and a bandwidth of 9 MHz. The proposed LNA achieves an average noise density of 11.3 nV/ √ Hz, and the 2nd harmonic distortion below −40 dBc with 0.1-Vpp input. The supply current is 85μA with a 1.8-V power supply, which is competitive with conventional LNAs by finer CMOS process. key words: amplifier, current-reuse, driver, ultrasound, LNA