T/R Switch Composed of Three HV-MOSFETs With 12.1-μW Consumption That Enables Per-Channel Self-Loopback AC Tests and −18.1-dB Switching Noise Suppression for 3-D Ultrasound Imaging With 3072-Ch Transceiver

This article presents an area- and power-efficient transmission/receiving (TX/RX)-isolation switch implemented in a 3072-ch ultrasound (US) in-probe 2-D array transceiver application-specific integrated circuit (ASIC) for real-time 3-D imaging. Conventional T/R switches that protect low voltage (LV) receivers from high voltage (HV) bipolar pulses require at least four HV-MOSFETs. The proposed dynamic gate-source shunt topology, which utilizes a negative-HV-transmit-driven shunt switch, eliminates area- and power-hungry HV-level shifters and ensures the OFF state of our T/R switch for HV/LV isolation during TX periods. In addition, source-driven HV-PMOS for ON/OFF control enables both gate charging and discharging using a single HV-PMOS. Thus, our T/R switch enables implementation with only three HV-MOSFETs for the first time in the world. The HV-level-shifter-less architecture also enables static-power-free operation in TX periods and consumption of only 12.1~\mu \text{W} in RX periods. Further, sequential input impedance control suppresses switching noise, which causes unwanted sound transmitted during TX to RX switching, by −18.1 dB. Moreover, by preparing an attenuation mode, a per-channel TX to RX self-loopback test can be performed. This function provides an on-wafer ac test without probing 3072 electrodes and it can be applied to the field diagnosis of assembled US probes.