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chapter 7, Nonlinearity
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Chapter Contents
- 7.1 Introduction
- 7.2 V/V Nonlinearity
- 7.3 V/e− Nonlinearity
Excerpt
7.1 Introduction
Two fundamental classes of gain nonlinearity exist for CMOS and CCD imagers: V/V nonlinearity and V/e− nonlinearity. Ideally, V/V nonlinearity for a camera system is dominated by the pixel's source follower amplifier. Nonlinearity characteristics for the amplifier can typically be controlled to less than 1% over a sensor's dynamic range. V/e− nonlinearity is related to sense node diode capacitance, which increases as charge collects (refer to Fig. 4.3). For CCDs, the sense capacitance change is usually negligible (typically < 0.2% nonlinearity). However, for CMOS detectors, V/e− nonlinearity can be significant, exceeding 200% for some pixel architectures (e.g., refer to Sec. 7.3).
7.2 V/V Nonlinearity
Figure 7.1 shows simulated PTCs with V/V nonlinearity characteristics.
©2007 Society of Photo-Optical Instrumentation Engineers
