A 36V Ultrasonic Driver for Haptic Feedback Using Advanced Charge Recycling Achieving 0.20CV2f Power Consumption

This paper presents an energy efficient high voltage (HV) ultrasonic driver for ultrasonic haptic feedback, designed to drive Piezo electric micro machined transducers (PMUT). To achieve low power consumption while driving large capacitive load of a piezo electric micro machined transducer, advanced charge recycling (ACR) is presented reducing the reactive power consumption without off-chip supply generation. To facilitate ACR in a compact footprint a bidirectional high voltage switch is proposed. The ultrasonic driver is able to drive a transducer capacitance of 240pF up to 36V swing with a frequency of 250kHz, only consuming 0.2GV²f power, outperforming bulky coil-based solutions. Realised in a high voltage 0.18µm bulk BCD technology, the driver only occupies 0.16mm².