A low power fuzzy logic based variable resolution ADC for wireless ECG monitoring systems

Portable low power and high quality monitoring devices play an important role for improving the performance of wireless body sensor networks. Mixed signal processor is required in ECG monitoring unit that comprises of analog front end, analog to digital converter (ADC) and digital signal processor. ADC is a core element in mixed signal processing unit and the proper design of ADC is crucial for data acquisition without losing heart related information and originality. The adaptive sampling has been used in the existing ADCs for choosing the sampling clock adaptively. Adaptive sampling rate ADC performs compression and reduces power consumption to some extent, however low powers ADCs are essential in wireless healthcare monitoring systems. In this paper, fuzzy logic based variable resolution controller is proposed to design the ADC efficiently in terms of circuit complexity and power. To further reduce the power consumption, power gating technique is adopted for static power reduction. Under 90 nm CMOS technology, gate count, core area utilization and power consumption have been determined for existing adaptive sampling ADC and fuzzy logic based adaptive sampling ADC. Cadence design tools have been used for the measurement of power in the designed circuit. The performance has been found to be better in terms of area and power that are very much essential for wireless ECG monitoring systems.