A compact 0.135-mW/channel LNA array for piezoelectric ultrasound transducers

This paper presents a power- and area-efficient 9-channel LNA array for piezoelectric ultrasound transducers to enable real-time 3D imaging with miniature endoscopic and catheter-based probes. In view of the relatively low impedance of piezoelectric transducers, the LNA is implemented as a capacitive feedback voltage amplifier, rather than a trans-impedance amplifier, to achieve a better noise-power trade-off. The use of a current-efficient inverter-based OTA with optimized bias scheme and dual-rail regulation further improves the power efficiency of the LNA while keeping the area compact: 0.01 mm² per channel. Electrical and acoustic measurement results show that the proposed LNA achieves a 0.6 mPa/√Hz input-referred noise at 4 MHz while consuming only 0.135 mW, which represents a noise efficiency 2.5 × better than the state-of-the-art.