The AD9238 is a dual， 3 V， 12-bit， 20 MSPS/40 MSPS/65 MSPS analog-to-digital converter （ADC）。 It features dual high performance sample-and-hold amplifiers （SHAs） and an integrated voltage reference. The AD9238 uses a multistage differential pipelined architecture with output error correction logic to provide 12-bit accuracy and to guarantee no missing codes over the full operating temperature range at up to 65 MSPS data rates. The wide bandwidth， differential SHA allows for a variety of user-selectable input ranges and offsets， including single-ended applications. It is suitable for various applications， including multiplexed systems that switch fullscale voltage levels in successive channels and for sampling inputs at frequencies well beyond the Nyquist rate. Dual single-ended clock inputs are used to control all internal conversion cycles. A duty cycle stabilizer is available and can compensate for wide variations in the clock duty cycle， allowing the converter to maintain excellent performance. The digital output data is presented in either straight binary or twos complement format. Out-of-range signals indicate an overflow condition， which can be used with the most significant bit to determine low or high overflow.