DESIGN AND FABRICATION OF AN ADDER CIRCUIT IN THE EXTENDED PHASE-MODELOGIC

We present the design and the fabrication of an adder circuit in the e xtended phase-mode logic Family. The phase-mode logic is a single Aux quantum(SFQ) logic which utilizes an SFQ as an information bit carrier . The single-bit adder circuit is made up of an INHIBIT gate which is the basic device of the phase-mode logic, The circuit has been designe d and fabricated using Nb/AlOx/Nb Josephson junctions with Josephson c ritical current density of 1.0kA/cm(2). In order to confirm the circui t operation, the fabricated adder circuit has been tested at low speed . Far investigating the possibility of a high-frequency operation, dc voltages generated by fluxon pulse trains have been measured. From the Josephson voltage-frequency relation, the result shows that the circu it has potential to complete the carry operation within 20psec.