| 摘要 |
PROBLEM TO BE SOLVED: To obtain an accurate evaluating device for magnetism detecting circuit which can be operated easily without giving any external magnetic field. SOLUTION: An evaluating device 17 is constituted of current sources I1 and I2 which are connected to the sensor drivers 13a and 13b of a magnetism detecting circuit 11 and supply desired sensor currents, switches SW1 and SW2 which connect and disconnect the current sources I1 and I2, a switch control circuit 22 which controls the opening and closing of the switches SW1 and SW2, and buffers 23a and 23b. The sensor currents are set at desired values by adjusting the current sources I1 and I2 and supplied to the magnetism detecting circuit 11 synchronously to the output waveforms of the sensor drivers 13a and 13b. The switch control circuit 22 generates control signals for controlling the opening and closing of the switches SW1 and SW2 synchronously to the outputs S1 and S2 of the sensor drivers 13a and 13b.
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