An AFE for Catheter-Based IEGM sensing with Inverter-based SAR ADC

An analog front-end (AFE) which contains a 1.2 V reconfigurable sensor amplifier and an inverter-based SAR ADC is presented in this paper. This sensor chip will be applied for a multi-electrodes catheter-based system for sensing intracardiac signals. The gain and bandwidth of the sensor amplifier can be flexibly configured to deal with the complex intracardiac conditions. The gm/Id design methodology is used to optimize its power efficiency. The inverter-based SAR ADC uses an inverter chain to quantize the sampling signal, which further reduces the hardware cost of the total system. Its inverter chain is biased in the subthreshold working area to achieve low power consumption. Fabricated in a 0.18 μm CMOS mixed-signal process, the total power of this sensor chip is 14.3 μW from a 1.2 V supply. The input-referred noise of the sensor amplifier is 1.89 μVrms, and its PSRR is 86 dB. The active area is 1.14 mm x 0.96 mm.

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