The ever-increasing resolution of CMOS imagers has steadily driven the requirements of readout circuitry. As the number of sensors on a chip increases, the bandwidth of the readout circuit must be increased correspondingly to maintain a constant frame rate. Column parallel A/D converters are commonly used to divide the conversions among many converters. However, implementing high-speed, high-resolution A/D converters at the column level is challenging because the entire circuit needs to be as narrow as the sensor. This thesis presents the design of a 10-bit, one million conversions per second column-parallel A/D converter. A factor of four increase in speed over conventional converters was achieved by combining techniques of successive approximation and two-step subranging in a distributed column-parallel architecture. The speed of the converter makes it suitable to be integrated with a 1-megapixel sensor array providing a frame rate at 1000fps with 11µm pixels in a 0.35µm CMOS technology.