An Ultrasound Receiver With Bandwidth-Enhanced Current Conveyor and Element-Level Ultrasound Transmitter for Ultrasound Imaging Systems

In this letter, we present an ultrasound (US) imaging system with a low-noise US receiver (RX) and an element-level US transmitter (TX) for a capacitive micromachined ultrasonic transducer (CMUT). The proposed US RX isolates the input parasitic capacitance
$(C_{P})$
from the front-end transimpedance stage by using a bandwidth-enhanced current conveyor. By reducing the effects of the
$C_{P}$
, the noise and power efficiency are improved compared to the conventional current readout circuits. Also, a US TX having a class-D output stage is implemented to excite the CMUT with 30-V unipolar pulses. Fabricated in a 180-nm BCD process, the proposed US RX achieves input-referred noise of 2.0 pA/
$\sqrt {\textit {Hz}}$
at 7.5 MHz and a bandwidth of 18 MHz with 25-pF CMUT capacitance while consuming 3.62 mW.