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

This paper presents a compact analog front-end (AFE) circuit integrated with a 100µm-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 mm2, consumes 0.8 mW and achieves an input noise density of 1.31 pA/ $\sqrt{\mathbf{H}} \mathbf{z}$ . The measured gain error of ±0.4 dB within a 36 dB overall gain range is 2.5 times better than the prior art.