The first data points collected by a PTC typically measure the read noise floor. This chapter reviews common CCD and CMOS read noise sources and their unique influence on PTCs. Table 11.1 lists the noise types in the order they will be presented.
Ultimately, a pixel's source follower MOSFET, shown in Fig. 4.3, limits the read noise floor. Fortunately, other noise sources can usually be reduced to negligible levels relative to source follower noise. For example, dark current noise is removed by cooling the sensor to a low operating temperature. Remarkably, source follower noise for high-performance CMOS and CCD cameras have been driven down to approximately one noise electron rms.
To provide the reader some insight to the variables behind source follower read noise, we present a general formula that theoretically determines its amplitude.
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