US Patent 11555744 Readout circuits and methods

Methods of sensor readout and calibration and circuits for performing the methods are disclosed. In some embodiments, the methods include driving an active sensor at a voltage. In some embodiments, the methods include use of a calibration sensor, and the circuits include the calibration sensor. In some embodiments, the methods include use of a calibration current source and circuits include the calibration current source. In some embodiments, a sensor circuit includes a Sigma-Delta ADC. In some embodiments, a column of sensors is readout using first and second readout circuits during a same row time.