A 5.34 nV/√Hz, 65.9dB PSRR, 0.0068mm²/Channel LNA Array for Pitch-Matched Ultrasound Receiver

This paper presents a compact, PSRR-enhanced 9channel LNA array for pitch-matched 3D ultrasound imaging systems, such as catheter-based steerable probes for transesophageal echocardiography (TEE) and intracardiac echocardiography (ICE). The inverter-based LNA employs split-capacitor and dynamic biasing to achieve low noise, low power, and small element pitch. To improve PSRR, the LNA utilizes a compact local regulator based on a flipped-voltage-follower (FVF) with dynamically biased current-mode feedforward ripple cancellation. This reduces inter-channel crosstalk from powerline, thereby minimizing image artifacts. Fabricated in a $0.18 \ \mu \mathrm{m}$ BCD process, the proposed LNA array, including bias and local regulator, occupies $0.0068 \mathrm{~mm}^{2}$ per channel and consumes 0.134 mW in average. Each LNA achieves an input referred noise (IRN) of $5.34 \mathrm{nV} / \sqrt{\mathrm{Hz}}$ and a PSRR of 65.9dB at 5MHz, outperforming the state of the art by 20dB.