| 摘要 |
PROBLEM TO BE SOLVED: To provide an impedance converter for a microphone for preventing noise from mixing into an output signal transmission path by equalizing impedances of both of balanced outputs by enabling adjustment of currents flowing through both two vacuum tubes for balanced output while using vacuum tubes as an impedance conversion element, and also to provide a microphone. SOLUTION: The impedance converter is equipped with: vacuum tubes 21, 22 in which output signals of microphone units 11, 12 are input into grids and output in cathode follower; FETs 31, 32 connected in cascade to the vacuum tubes 21, 22 and defining currents flowing through the vacuum tubes 21, 22; and bias circuits for applying a bias voltage to the grids of the vacuum tubes 21, 22. In the converter, the vacuum tubes, the FETs, and the fixed bias circuits are paired to be symmetrically connected and two cathode follower outputs become balanced output. The converter is further equipped with an adjusting member 40 for adjusting a current flowing between the paired vacuum tubes 21, 22 to adjust the balance of the balanced output between the paired fixed bias circuits. COPYRIGHT: (C)2011,JPO&INPIT
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