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An ultra-low power CMOS image sensor is designed for endomicroscope applications. The chip will be fabricated through Global Foundries 0.18µm standard CMOS process with 1V power supply. The total power consumption is 6µW for 96×96 array with 5fps frame rate, where global amplifier consumes 3.3 µW, 10-bit SAR ADC consumes 900nW at 50kS/s, and on-chip digital processing further reduces IO power consumption down to 1.6µW.

A high-resolution column-parallel folding-integration/cyclic cascaded (FICC) ADC with a pre-charging technique for CMOS image sensors is presented in this paper. To achieve high-resolution data conversion with multiple sampling, a pre-charging technique is applied to the sampling circuits of the FICC ADC to reduce the influence of incomplete discharging of historical previous samples. This technique effectively reduces differential nonlinearity of the ADC. The prototype chip with 1504 columns FICC ADC array has been implemented and fabricated in 110 nm CMOS technology. The measured DNL of column-parallel FICC ADC with 128 times multiple sampling is −1/4.73 LSBs in sampling speed of 13 KS/s and 19-bit resolution.

The influence of transverse mode were researched with the injection current changing via experiments conducted with 980nm oxide-confined vertical cavity surface emitting lasers (VCSELs). Based on the spatio-temporal rate equation, the injection parameter dependence of the transverse mode characteristics of weak-index guiding VCSELs were theoretically researched by integrating the spatially dependent part. The result of the experiment indicated that the higher-order modes begin to emerge and exhibit strong competition with the injection current increased when the oxidized aperture was kept unchanged, and the distribution of the carrier transfers from the center to the edge. Furthermore, the main order becomes weaker because of the spatial hole burning. Compared with the appearance of higher-order modes with different oxidized aperture, the small injection aperture exhibits better single mode behavior.