“…Image Sensors are increasingly becoming "Key Devices" for a broad range of products, such as medical, measuring instruments, robot vision, specialized surveillance cameras, broadcast and other industrial applications, etc, where wide dynamic range, high sensitivity, high frame rate and low noise are vital specifications to realize the best possible imaging and sensing performance. For example, CMOS image sensors can achieve over 100 dB of simultaneous-capture wide dynamic range (SCWDR) [1]. In general, development of high-resolution and wide dynamic range sensors is limited by several factors, such as vertical and horizontal readout circuit, analog to digital conversion, and data output from the sensor, then putting forward high demands on column analogto-digital converters (ADCs), which is crucial unit to ensure sufficient vertical readout period in image sensor as shown in Fig.…”