The AD9985 incorporates an auto-offset function. The Auto-Offset works by monitoring the output of each ADC during the clamp period and then calculating the required offset setting to yield a given output code. When auto- offset is enabled (Reg. 0x1D:7 = 1), the settings in the target code registers (0x19 to 0x1B) are used by the auto-offset circuitry as desired clamp codes. The circuit compares the output code during clamp to the target code and adjusts the offset up or down to compensate. In auto-offset mode, the target code is an 8-bit, twos complement word, with Bit 7 of their respective registers being the sign bit.