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 μW 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.