| 摘要 |
PROBLEM TO BE SOLVED: To provide an impedance-measuring apparatus which measures any impedance values with a high resolution, a high accuracy and fits for integration of circuits. SOLUTION: A since wave ROM 1 stores a time-discrete sine wave data. A control circuit 10 reads the sine wave data as it is and after shifting a phase of the data by 90 deg. in a time-sharing manner. A D/A converter 2 converts the data to an analog signal and a voltage/current converter 3 converts to a current and applied to an object 11 to be measured. An A/D converter 4 converts a response signal from the object 11 to be measured to a digital signal. A multiplier 5 multiplies the converted digital signal by the sine wave data from the sine wave ROM 1 and by the 90 deg.-shifted sine wave data, respectively. An accumulator 6 holds the multiplied results separately into a SIN register 7 and a COS register 8. This process is repeated by predetermined cycles. Thereafter, a microcomputer 9 carries out a predetermined operation to contents held in the SIN resister 7 and COS register 8, thereby obtaining an impedance value of the object 11.
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