A Low-Power Compact HV TX/RX Switch Composed of Three HV-MOS Transistors for Ultrasound Imaging Front-End ASICs

A. Amini (Univ. of Pavia, Italy)

This paper presents a compact and low-power high-voltage (HV) transmit/receive (TX/RX) switch for ultrasound imaging front-end (FE) application-specific integrated circuits (ASICs). The proposed design is derived from a previously reported architecture and introduces several optimizations to improve power efficiency and silicon area. The switch is composed of only three HV MOS transistors to isolate low-voltage (LV) receiver circuits from bipolar excitation pulses up to 200 Vpp while operating from a 3.3-V supply. To improve efficiency, the HV devices in the replica bias branch are replaced with LV transistors, the gate–source resistor is increased to reduce the bias current while maintaining the required gate drive voltage, and the conventional constant bias current is replaced with a pulsed current driver that charges the gate capacitance only during the TX-to-RX transition. Implemented in a 160-nm BCD-SOI technology, the proposed switch achieves an off-isolation of −42 dB at 3 MHz with an on-resistance of 190 Ω.. Compared with the previous architecture, the design reduces power consumption from 660 μW to 66 μW and decreases the silicon area by approximately 25%.