1/f Noise Measurement in CMOS Image Sensors

This paper describes an in-situ pixel source follower power spectral density (PSD) measurement method that does not require any specialized test equipment. This method requires a dual port CMOS image sensor with analog outputs that allow differential time series noise measurements. We describe the sensor circuits and measurement techniques used for collecting data. We derive an estimator for the PSD based on the measured data. We also present a technique for estimating the confidence interval of the PSD based on Bootstrap re-sampling. Using our estimate of the PSD, we derive estimators for the SPICE NLEV3 1/f noise model parameters AF and KF . We also determine confidence intervals for these estimators. Using this method we present the estimated source follower PSD for a CMOS image sensor fabricated in a 0.18μm CMOS process with 3.3μm X 3.3μm pixels. We also present the estimated values of AF and KF based on the estimated PSD.