HYSTERESIS CHARACTERISTIC TYPE DIGITAL FLL DEVICE BY DOUBLE COUNTER SYSTEM FOR SQUID

摘要

PROBLEM TO BE SOLVED: To attain a high resolution, a high through rate and a high dynamic range without using an expensive circuit component having the large number of processing bits and capable of high-speed processing, in a SQUID fluxmeter.;SOLUTION: In this digital FLL circuit by a double counter system, two counters, namely, a variation counter 37 in digital FFL for performing high-speed processing and a reproduction counter 53 in a computer for control and measurement are utilized. In this invention, a hysteresis characteristic having 1Φ₀ plus margin is used. Namely, while a change of the state of a magnetic flux is counted by the counter, control is performed at the changing time so as to pass along a route which is different between the increasing case of the magnetic flux and the decreasing case thereof, to thereby stabilize control.;COPYRIGHT: (C)2006,JPO&NCIPI