Adaptive Pulse Skipping for Power Optimized On-Chip Phased Array Driving for Ultrasound (US) Neuromodulation

Abstract

Power efficiency is critical for enabling the long-term use of implantable and wearable ultrasound (US) neuromodulation systems, where excessive power consumption leads to thermal dissipation and frequent battery replacement. Conventional therapeutic phased arrays typically generate equal pressures from all elements, not taking into account the directivity of each element, and thus the different source contributions to the focal spot, leading to power inefficiency. Although prior methods allow control of source pressure at the element level, such as driver supply control, duty cycle adjustment, or deterministic pulse skipping, they either require complex circuitry, introduce dynamic switching losses, or cause undesirable temporal fluctuations in focal pressure, respectively. To address these limitations, we introduce a novel driving scheme that explores pseud-random pulse skipping to control element-level source pressure and thus optimize power consumption in 2D phased array ultrasound transmitters. The pseudo-random pulse skipping approach allows for regulating the source pressure in each element while preserving a stable pressure at the focal spot, which is required for therapeutic applications. The driving scheme for a single element was implemented in an ASIC, and the result shows that by having different percentages of pulse skipping, we can also modulate the power consumption of the driving channel.