The Modulation Transfer Function is a common metric used to quantify image quality but inter-pixel crosstalk analysis is also of interest. Because of an important number of parameters influencing MTF, its analytical calculation and crosstalk predetermination are not an easy task for a CMOS image sensor. A dedicated test chip (using a technology optimized for imaging applications) has been developed in order to get both MTF data and influence of the various areas of the pixel to its own response and the one of its neighbors. In order to evaluate the contribution of pixel elementary patterns (particularly the in-pixel readout circuitry), several kernels of shielded pixels have been implemented with the central pixel locally unmasked. The results obtained with pixel kernels and direct MTF measurements, performed on the same chip at different wavelengths, are analyzed and compared in order to correlate them and draw conclusions that can be applied at the design level. Additional data resulting from spotscan measurements allow us to verify our hypothesis on different pixels.
展开▼
