Design of Front-End Receiver Electronics for 3D Trans-Esophageal Echocardiography

Abstract

The motivation behind this thesis is that cardio-vascular diseases claim the highest number of lives each year globally. In order to enhance the accuracy in diagnosis, construction of 3D images of the heart is required. From these images, precise information can be obtained regarding the 3D anatomy of the heart and its functioning. Trans-Esophageal Echocardiography (TEE) is a promising technique to achieve this kind of precision in diagnosis. The objective of my thesis is to perform optimization at the system and circuit level, in order to improve power-efficiency and area-efficiency of the front-end receiver electronics. This electronic circuitry is integrated at the tip of a miniature TEE probe, which will be inserted through the esophagus close to the heart of the patient for diagnosis (via a gastroscopic tube). The signal processing chain of the receiver electronics consists of a Low Noise Amplifier (LNA), a Micro-Beamformer that performs delay and sum operation, and a Time Gain Compensation (TGC) amplifier. A novel low-power high-dynamic-range micro-beamformer is designed in TSMC 0.18 µm CMOS technology. The dynamic range is enhanced substantially compared to a previous implementation. This has been achieved by employing an Offset Calibration Loop (OCL). The proposed design is power-efficient, such that the total power consumption is almost a factor of 5 lower compared to the state-of-the-art design. The increase in thermal noise level is marginal (6.5%) after incorporating the OCL.