Parity generator circuit using a multistate resonant tunnelling bipolar transistor

A four-bit parity generator circuit using a single resonant tunnelling bipolar transistor (RTBT) exhibiting two negative transconductance regions in the characteristics, is demonstrated. The circuit uses only one transistor as compared to 24 needed in conventional logic. The present circuit also provides significant advantages over previous parity generator circuits using resonant tunnelling diodes. The same circuit, when used with only two input bits, will act as an exclusive-NOR gate.