A Reduced-Wire ICE Catheter ASIC With Tx Beamforming and Rx Time-Division Multiplexing

Abstract

This paper presents a single chip reduced-wire active catheter application-specific integrated circuit (ASIC), equipped with programmable transmit (Tx) beamforming and receive (Rx) time-division multiplexing(TDM).Theproposedfront-endASICis designed for driving a 64-channel one-dimensional transducer array in intracardiac echocardiography (ICE) ultrasound catheters. The ASIC is implemented in 60 V 0.18-μm HV-BCD technology, integrating Tx beam formers with high voltage pulsers and Rx front end in the same chip, which occupies 2.6 × 11 mm2 that can fit in the catheter size of 9 F (<3 mm). The proposed system reduces the number of wires from >64 to only 22 by integrating Tx beamformer that is programmable using a single low-voltage differential signaling data line. In Rx mode, the system uses 8:1 TDM with direct digital demultiplexing providing raw channel data that enables dynamic Rx beamforming using individual array elements. This system has been successfully used for B-mode imaging on standard ultrasound phantom with 401 mW of average power consumption. The ASIC has a compact element pitch-matched layout, which is also compatible with capacitive micromachined ultrasound transducer on CMOS application. This system addresses cable number and dimensional restrictions in catheters to enable ICE imaging under magnetic resonance imaging by reducing radio frequency induced heating.

Overview of Ultrasound Detection Technologies for Photoacoustic Imaging

“…In clinical transducer arrays, each element is connected through a long wire to the analog-front-end (AFE) unit which includes transmit and receive beamformer, preamplifier, switches, and analog-digital converters (ADCs). Although this keeps all the electronics in one place, this arrangement causes interferences and reflections along the cable [137,138]. The number of cable connections can be reduced by multiplexing, however that has negative consequences such as limited bandwidth and slower processing [139].…”

A 1.25 μJ per Measurement Ultrasound Rangefinder System in 65 nm CMOS for Explorations With a Swarm of Sensor Nodes

“…PZTs typically have a nominal operating frequency spanning from a few tens of kHz to several hundreds of kHz with a relatively low bandwidth [25], [26]. Although Capacitive Micromachined Ultrasound Transducers (CMUTs) have been used in literature [27] to achieve a larger bandwidth compared to PZTs, the high-voltage DC bias requirement of CMUTs [28] is an important drawback in battery-operated applications. Accordingly, PZT1 and PZT2 are chosen as commercially available piezoelectric transducers with a nominal resonance frequency of 40 kHz and 100 kHz, and an input capacitance of 2 nF and 1 nF, respectively [29].…”

Advances in Capacitive Micromachined Ultrasonic Transducers

“…Analog multiplexing of the transducer channels and applying synthetic aperture imaging can reduce the number of connections to as low as two [ 65 ] with some compromise in the imaging quality and frame rate. A more efficient approach is to integrate TX beamformers and analog multiplexers with the CMUT array at the catheter tip to reduce the cable count without compromising the image quality [ 48 , 66 , 67 ].…”

“…Combining all of these in a single chip provides the best signal integrity but may compromise signal quality to some degree. However, HV-BCD processes seems to overcome such problems [ 57 , 67 , 68 ]. Building ultrasound imaging systems on a chip or even on multiple chips paves the way to very low cost, ultra portable ultrasound imaging systems.…”