CMUT front-end circuits designed in a high-voltage CMOS process and the phase measurement receiver circuit

The design of front-end circuits that interface with the capacitive micromachined ultrasonic transducer (CMUT) is presented. Both the transmit pulser and the receive amplifier were fabricated in a high-voltage CMOS process. The pulser employs a push-pull output stage to generate a 30V pulse with a pulse width of less than 100ns, while driving a 12pF load. The receive amplifier is a single-stage opamp in a transimpedance configuration. Experimental results of both circuits working with the CMUT are presented. In addition, a novel phase measurement receiver circuit for CMUT is also presented. The circuit uses phase change to monitor the change in CMUT capacitance. It offers several advantages over the conventional solution. A behavioral model was developed to simulate the performance of the new receiver circuit.