Shift register performance at 4 GHz

Two mask layouts were designed to give Josephson shift register operation above 2 GHz. Custom instrumentation was assembled for tests up to 4 GHz. Shift registers using coplanar waveguide structures for on-chip power distribution operated properly up to 3.3 GHz. Better performance was obtained when power was distributed through microstrip transmission lines. At the tester limit of 4 GHz, microstrip circuits operated properly with bias margins of +or-15%.