Mutual inductance and noise of high-T-c SQUIDS with flip-chip and integrated input coils

We investigated the mutual inductance and the noise of high-T-C superconduc ting quantum interference devices (SQUIDs) with flip-chip and integrated in put coils. The de SQUIDs are prepared on bicrystal substrates with a misori entation angle of 30 degrees, The number of turns of the input coils is var ied between 5 and 25 turns, For 19-turn input coils, the mutual inductance is about 0.75 nH and 1 nH for the flip-chip and integrated SQUIDs, respecti vely. The spread in noise at 1 Hz is less than a factor of 2 for the flip-c hip devices and about a factor of 5 for the integrated devices.