An ECG-on-Chip for Wearable Cardiac Monitoring Devices

This paper describes a highly integrated, low power chip solution for ECG signal processing in wearable devices. The chip contains an instrumentation amplifier with programmable gain, a band-pass filter, a 12-bit SAR ADC, a novel QRS detector, 8K on-chip SRAM, and relevant control circuitry and CPU interfaces. The analog front end circuits accurately senses and digitizes the raw ECG signal, which is then filtered to extract the QRS. The sampling frequency used is 256 Hz. ECG samples are buffered locally on an asynchronous FIFO and is read out using a faster clock, as and when it is required by the host CPU via an SPI interface. The chip was designed and implemented in 0.35µm standard CMOS process. The analog core operates at 1V while the digital circuits and SRAM operate at 3.3V. The chip total core area is 5.74 mm2 and consumes 9.6µW. Small size and low power consumption make this design suitable for usage in wearable heart monitoring devices.