Analogue signal processor cuts power consumption in heart monitors
1 min read
Belgian research institute IMEC and its associate Holst Centre are presenting details of an analogue signal processor asic at ISSCC in San Francisco. The device is said to reduce the overall power consumption of an ambulatory heart activity signal monitoring systems by more than five times. The partners say this is a major step towards autonomous wireless sensor systems to monitor monitor patient's health constantly.
IMEC claims that modern biomedical wireless sensor systems waste a lot of power either in the dsp, by processing biopotential signals continuously, or in the radio, by transmitting raw data over the wireless link.
Its solution is to use an adaptive sampling scheme, based on activity detection, to reduce the amount of data which needs to be processed by the dsp or transmitted by the radio.
The device has a power consumption of 30µW and works from a 2V supply. It features an ECG readout channel, two quadrature readout channels for continuous time monitoring of electrode-tissue impedance, and two quadrature readout channels for tracking signal fluctuations in a specific frequency band. The asic also includes an activity detector that senses the frequency content of the ECG signal and adapts the sampling rate of an integrated a/d converter for digitisation of the ECG signal.
The analogue signal processing stage reduces the power consumption of the dsp by a factor of 11 and wireless transmission by six times. This is said to result in an overall system power dissipation of less than 300µW for a complete wireless heart activity signal monitoring system.
