A mixed-signal ASIC for triple-chamber cardiac pacemakers with heart resistance measurement

This paper presents a mixed-signal ASIC for triple-chamber pacemakers. The ASIC performs four major functionalities: 1) sensing of heartbeat signals; 2) measuring the heart resistance of three chambers independently to diagnose the attachment status of the electrodes and provide additional information about the pathological status of the patient´s heart; 3) generating stimulus pulses with programmable magnitude and pulse width; 4) receiving commands and configuration data from MCU, and transferring register data to MCU through the SPI interface. The ASIC is fabricated in a 0.35-μm BCD technology with a chip area of 3.8×3.8 mm2. Measurement results show that the magnitude of the stimulus pulses can be programmed from 0. 1 to 7.4 V with 0.1-V step. Almost linear heart resistance measuring is achieved in the resistance range of 250 to 4000 Q. Average current consumption is 4 μA from a 2.8-V supply.