| 摘要 |
PURPOSE: To provide a high impedance circuit for dealing with a high frequency as well by ignoring stray capacity with a transistor(TR) and a coupling capacitor. CONSTITUTION: A current mirror circuit is formed by complementary TR T1 and T2 for which an input signal is supplied to their bases, a current mirror circuit is formed by similar complementary TR T3 and T4, and the high impedance circuit is formed by the cascade connection of the TR T1 and T3 and the TR T2 and T4. Then, an emitter/collector current to flow to the TR T1 is fed back to through a capacitor CO to the emitter of the TR T2. When the capacity of this capacitor CO is selected to CO|CSO in comparison with stray capacity CSO, the stray capacity can be ignored by the coupling capacity and the high impedance circuit for dealing with the high frequency can be provided.
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