Charge-conserved analog-to-time converter for a large-scale CMOS biosensor array

In a large-scale time-domain sensor array, propagation of the pulse voltage causes considerable pulse distortion due to a large bitline capacitance. This work demonstrates a time-domain potentiometric biosensor array with a newly-proposed 4T sensor cell and pulse processing circuit functioning as a charge-conserved analog-to-time converter (CCATC) that converts from input analog voltage to a pulse current. By employing the pulse current with the fixed bitline voltage, short-pulse detection with high energy efficiency becomes possible. Simulation results for 600-nm CMOS technology demonstrate the detection of a 10-ns pulse, even with a large bitline capacitance of over 10 pF.