Rapid single flux quantum T-flip flop operating up to 770 GHz

• Published in: IEEE transactions on applied superconductivity Vol. 9; no. 2; pp. 3212 - 3215
• Main Authors: Chen, W., Rylyakov, A.V., Patel, V., Lukens, J.E., Likharev, K.K.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.06.1999; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Circuit properties; Circuits; Critical current; Critical current density; Devices; Digital circuits; Electric potential; Electric, optical and optoelectronic circuits; Electron beam lithography; Electronic circuits; Electronics; Exact sciences and technology; Flux; Frequency; Josephson junctions; Niobium; Pulse generation; Resistors; Superconductivity; Testing; Voltage; Critical current density; Scanning electron microscopy; Planarization; Experimental result; Circuit design; Computer simulation; Josephson junction; Manufacturing process; Output voltage; Digital circuit
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/77.783712

Rapid Single Flux Quantum (RSFQ) T-flip flops (TFFs) operating up to 770 GHz have been demonstrated at 4.2 K. The devices, consisting of either resistively shunted or unshunted Josephson junctions, are fabricated using a planarized Nb/AlO/sub x//Nb trilayer process. Electron beam lithography is used to pattern all levels with a minimum junction area less than 0.1 /spl mu/m/sup 2/. Critical current densities of 0.5 mA//spl mu/m/sup 2/ and 2.5 mA//spl mu/m/sup 2/ are used for the shunted (tested at 1.8 K) and unshunted devices (tested at 4.2 K) respectively. The input and output frequencies of the TFFs are obtained from the input and output voltages by the Josephson relation. The output voltage is exactly half of the input voltage when the divide-by-two operation is correct.