A Fully Integrated Low-Power Capacitive Sensor Frontend With Automatic Tuning Scheme

In this brief, a reconfigurable low-noise fully integrated capacitive sensor frontend with an on-chip tuning scheme is proposed to enhance the flexibility, reliability, and accuracy with a low power consumption. The sensor frontend is composed of a charge sensitive amplifier with a new reset network followed by bandpass amplifiers to further amplify the output signal and also to achieve a Gaussian pulse shaping. Automatic tuning circuits have also been proposed and implemented to make the interface resilient to PVT variations and improve accuracy. The frontend can process the signals of both polarities and the effect of the sensor dark current on the output is negligible. The readout circuit has been simulated using a standard 0.18 mu m CMOS process. The post-layout simulation results prove a highly tunable conversion gain and show a maximum value of 25.7 mV/fC and equivalent noise charge (ENC) of almost 106 e-rms with a power consumption of 371 mu W.