Abstract: A DC coupled serial data stream receiver system utilizing a switched capacitor based differencing front end which compares the instantaneous value of an analog voltage with respect to its long term minimum value to a series of reference voltages V1 to Vn in a flash analog to digital converter style front end. The circuit is designed to interface directly to a discrete fiberoptic preamplifier. The receiver can handle multiple amplitude serial data as produced by multiple fiberoptic transmitters on the same fiber without any data loss and without any interruption in data transfer being necessary as one transmitter halts and a second one starts transmission.

Abstract: An integrated circuit has an I/O circuit that is connected to an I/O PAD. The I/O PAD may have greater voltage than the VDD associated with the integrated circuit so there is provided a switching circuit that is connected between the VDD and the I/O PAD. An output circuit is also provided that comprises n-channel transistors connected between the PAD and the ground. There is a cascode arrangement of p-channel transistors connected between the I/O PAD and VDD.