Integrated circuits for an implantable CW Doppler ultrasonic flowmeter

A totally implantable telemetry system for monitoring instantaneous blood flow in major arteries within animals has been developed. The system provides a new and necessary tool for accurate quantitative measurements in the study of cardiovascular disease. Low voltage micropower integrated circuits are essential in this application to achieve the low power consumption, small size, and high reliability required in an implantable system. The novel features of a family of custom monolithic linear integrated circuits developed for use in the blood flowmeter are described. These circuits include a 6-MHz exciter oscillator, a 6-MHz low noise AM receiver, and a 100-MHz FM transmitter.