A Pitch-Matched Analog Front-End with Continuous Time-Gain Compensation for High-Density Ultrasound Transducer Arrays

Abstract

This paper presents a compact analog front-end (AFE) circuit integrated with a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$100\mu\mathrm{m}$</tex> -pitch 2D ultrasound transducer array for 3D imaging. To realize time-gain compensation, it consists of two variable gain stages, both of which employ a novel complementary current-steering network to realize continuously-variable gain. The first stage is a transimpedance amplifier with a hardware-sharing current-reuse input stage to save power and area. The second stage is a class-AB current amplifier. Per channel, the AFE occupies only 0.025 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , consumes 0.8 mW and achieves an input noise density of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.31\ \text{pA}/\sqrt{\mathrm{H}}\mathrm{z}$</tex> . The measured gain error of ±0.4 dB within a 36 dB overall gain range is 2.5 times better than the prior art.