Title:  Single-chip Reduced-wire Active Catheter System with Programmable Transmit Beamforming and Receive Time-division Multiplexing for Intracardiac Echocardiography

Committee: 

Dr. Ghovanloo, Advisor

Dr. Degertekin, Co-Advisor   

Dr. Emelianov, Chair

Dr. Ayazi

Abstract:

The objective of the proposed research is to develop a single-chip reduced-wire active catheter system. Current commercial intracardiac echocardiography (ICE) catheters offer a limited 2-D or 3-D field of view in spite of large number of interconnections, which are mainly determined by the number of array elements and ground connections. Each element in the transducer array is connected to corresponding analog-front-end (AFE) system with a separate long wire, which is a significant limitation for improving image quality and increasing the number of elements. Also, in order to use ICE catheters under MRI instead of the ionizing X-ray radiation-based angiography, the number of interconnect wires in the catheter should be minimized to reduce RF-induced heating from metal connection. The proposed research is to develop a single-chip reduced-wire active catheter system which integrates both the transmit beamforming and receive time-division multiplexing (TDM) for ICE. The proposed front-end application-specific integrated circuits (ASIC) can be used with both piezoelectric and capacitive micromachined ultrasound transducer (CMUT) arrays. This proposed single chip solution achieves significant cable reduction by adopting a 8:1 TDM analog Rx with direct digital de-multiplexing (DDD), and Tx-beamformer with high voltage pulsers, which can be programmed with a single low voltage differential signaling (LVDS) data line for loading Tx beamforming profile and controlling Rx gain. The received raw ultrasound echo signals are sent to analog-to-digital converters (ADC) in the backend system, where DDD is performed in field-programmable gate array (FPGA) for real-time image processing in the digital domain. This approach can also be combined with sub-array beamformer (SAB) technique to achieve massive cable reduction especially for 2D imaging arrays.