This short course explores the interaction of Analog Front End (AFE) electronics with passive ultrasound transducers, advances to the integration of the AFE with in-probe electronics, and finally considers the implications on ultrasound system design.

The course starts by considering the electronics within a typical AFE. A basic electronics primer is provided including Characteristic Impedance, Impedance Matching, Cable Selection then Analog and Switched Mode Transmit Circuits, Transmit/Receive Switches and Multiplexers, Receiver AFE, Amplification including Noise Factor and Noise Figure, Filtering and Analog to Digital Convertors (ADC).

With an understanding of the discrete building blocks, active probes with in-probe electronics and the associated system partitioning will be studied, with use cases in SNR enhancement and the realization of 3D probes and wearables. The use of Application-Specific Integrated Circuits (ASICs) and the integration of such ASICs with ultrasound transducer arrays will be discussed. Approaches to realizing in-probe transmit and receive circuitry will be introduced. Multiplexing, sub-array beamforming and in-probe digitization will be discussed as approaches to realizing the channel-count reduction that is crucial for high-element-count 3D probes. 

The course concludes by exploring ultrasound system design in context of passive probes with separate AFEs and active probes with in-probe electronics. The challenges and techniques for data acquisition (both multiplexed and full-channel), storage and transfer will be discussed. Beamformer implementations will be introduced, with emphasis on delay-and-sum. Techniques for data post-processing for B-mode and Doppler modes will be covered. Finally, communication with active probes and the handling of pre-beamformed data will be discussed.