A class of Analog to Digital Converters require closely matched differential inputs in terms of amplitude and phase. At the same time, it is also important to provide input signals that exhibit distortion levels that are at least b60 dB down from nominal inputs of nominal 1V at frequencies in excess of 25 MHz. A to D's which run on a single 5V supply can be damaged or misbehave if the input range is exceeded. The circuit of Figure 1 satisfies these diverse requirements.