A CMOS high-voltage DC-DC up converter dedicated for ultrasonic applications

This paper concerns the design and implementation of a fully integrated high voltage CMOS DC-DC up converter (VHVUC) dedicated to ultrasonic transmitters. This VHVUC new topology, followed by a drive amplifier, is based on a multiple-stage charge pump circuit and a level-up shifter is used in each stage as a clock generator in order to increase exponentially the DC voltage. A drive amplifier, based on a level-up stage and a class D switching output stage. It is used to excite the ultrasonic transducer, resonate at 3.5 MHz. Simulation results of the proposed converter, using a 0.8μm CMOS/DMOS High-Voltage process technology, show output voltage of 200 V with 83% gain voltage factor and a 95 mV output ripples for 2 MHz frequency. Also, the drive amplifier for single shock excitation show a 140 V spike at the transducer element with a pulse repetition time of 260 μs and a rise and fall times of 220 ns and 713 ns respectively with a peak current through the transducer element of 25 mA. These results show the feasibility of applying HV process technology to replace conventional electronic transmitter technology.