To provide a superconducting sigma delta modulator which realize a high-resolution AD converter.
In the superconducting sigma delta converter, it is necessary that a time constant Ls/Rs of an integrator is sufficiently high in order to avoiding evils like a failure to raise the resolution or degradation of the linearity, however Ls cannot be made sufficiently large because it is necessary that a feedback quantity Φ0/L0 (Φ0: magnetic flux quantum) is not buried in the thermal noise from an overdamping Josephson element 4 of a comparator. In order to resolve this problem, a Josephson transmission line including an underdamping Josephson element is used as a magnetic flux quantum pair generation circuit 20; and when the Josephson element 4 of the comparator exceeds a threshold to output one single magnetic flux quantum, the magnetic flux quantum is multiplied in this circuit 20 to feed back plural single magnetic flux quanta to the integrator. Ls and the time constant are made sufficiently large in accordance with by increase in the feedback quantity to realize a high resolution.
| JPH04152764 | A/D CONVERTER |
| JPH07154258 | METHOD AND EQUIPMENT FOR TESTING A/D CONVERTER |
| WO/2002/049217 | ADAPTIVELY CALIBRATING ANALOG-TO-DIGITAL CONVERSION WITH CORRECTION TABLE INDEXING |
NAGASAWA SHUICHI
HASEGAWA HARUHIRO
SUZUKI HIDEO
MIYAHARA KAZUNORI
ENOMOTO YOICHI
INT SUPERCONDUCTIVITY TECH
NEC CORP
HITACHI LTD
FUJITSU LTD
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