An ultra-low-power fully integrated ultrasound imaging CMUT transceiver featuring a high-voltage unipolar pulser and a low-noise charge amplifier

In this paper, we report on the development of a fully-integrated, low-power analog frontend circuit, consisting in a high-voltage unipolar pulser and a low-noise charge amplifier, specifically designed for 1D CMUT arrays operating in the 1-15 MHz range. The proposed circuit comprises a high-voltage unipolar pulser, a T/R switch, and a low-noise charge amplifier (LNA), which were carefully co-designed in order to minimize the overall parasitic capacitance and power consumption. The high-voltage pulser allows generating up to 100-V unipolar pulses. The T/R switch was designed to achieve sufficient isolation of the LNA during transmission together with a low parasitic resistance in on state. The LNA is based on a capacitive feedback topology providing sufficient bandwidth and better noise-power performance than commonly adopted trans-resistance topologies. Chip prototypes were fabricated using a BCD-SOI technology available at STMicroelectronics. Experimental characterization results are achieved in conjunction with a 10 MHz CMUT linear array developed for medical imaging applications.