Patent US 3,967,270

The disclosure describes an improved analog-to-digital converter which enables the use of a reference voltage having the same polarity as the input analog voltage being converted. The converter employs an operational amplifier having a capacitive feedback network, an inverting input, and a non-inverting input. The inverting input is periodically disconnected so that the output of the operational amplifier slews to a new value without substantially changing the voltage across the capacitive feedback network.