Josephson direct coupled logic (DCL)

Direct Coupled Logic (DCL) circuits utilize a novel isolation device which provides isolation between a logic gate and its input signals by switching a Josephson junction to its high impedance state. The input signal currents are directly injected into the logic gates instead of being magnetically coupled through transformers as in many earlier Josephson logic circuits. The resultant improvements are higher circuit density, improved punchthrough speed, DOT-OR capability and parallel fan-out. Gate delays for 2- and 4-input AND DCL circuits are estimated to be 40 ps and 51 ps respectively. The corresponding power dissipation is estimated to be 1.8µW and 3.6µW.