| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an impedance measuring device capable of measuring high impedance for a wide band frequency to be measured. SOLUTION: The influence of an in-phase voltage giving an error to the float type ammeter of an impedance measuring device by a voltage current measuring method is eliminated from a wide frequency band. In other words, in the float type ammeter for measuring the voltages of both ends of a current detection resistor, an in-phase component is eliminated in a high measured frequency band by a balun 35 and, in a low band, an in-phase component is eliminated by a differential amplifier 31. The in-phase eliminating actions of the balun 35 and the differential amplifier 31 cross over each other in a frequency in which the impedance of a capacitor 33 is equal to the excited impedance of the balun 35. In a cross-over frequency, a resistor 37 is selected to lose resonance produced by the excited impedance of the capacitor 33 and the balun 35 and cross-over characteristic is made smooth.</p> |
