This paper presents a power- and area-efficient front-end ASIC that is directly integrated with an array of 32 × 32 piezoelectric transducer elements to enable the next-generation miniature ultrasound probes for real-time 3-D transesophageal echocardiography. The 6.1 × 6.1 mm2 ASIC, implemented in a low-voltage 0.18 μm CMOS process, effectively reduces the number of cables required in the probe's narrow shaft by means of 96 sub-array beamformers, which have a compact element-matched layout and employ mismatch-scrambling to enhance the dynamic range. The ASIC consumes less than 230 mW while receiving and its functionality has been successfully demonstrated in a 3-D imaging experiment.@en

This paper presents an approach to time-multiplexing multiple receive signals in a miniature ultrasound probe onto a single micro-coaxial cable. The resulting reduction in the number of receive cables alleviates the design of high-element-count endoscope- or catheter-based ultrasound probes. A prototype multiplexing system is presented that employs a custom multiplexing chip that uses current-mode drivers to combine four receive channels, sampled at 25 MHz each, on a single 3-m micro-coaxial cable. On the system-side of the cable, a transimpedance amplifier turns the multiplexed signal back into a voltage, after which it is digitized and equalized to correct for channel-to-channel crosstalk due to non-idealities of the cable. The chip has been implemented in a 0.18 μm CMOS process and consumes less than 1 mW per input channel. Experimental results show that the system can successfully convey 6 MHz Gaussian-shaped pulses applied to the four input channels of the multiplexing chip to the system with a channel-to-channel crosstalk below -31 dB.@en