| 摘要 |
PURPOSE:To obtain a transfer characteristic which is not influenced by a variance of a current amplification factor beta, by inputting a current flowing to a minus input of a differential amplifier, from a base of a transistor, and controlling an output voltage of the differential amplifier. CONSTITUTION:As for an operational amplifier 11, an inversion input terminal is grounded through an input current source 12, and a non-inversion input terminal is grounded. An output terminal 13 of the operational amplifier 11 is connected to an emitter of a transistor Q1, and a base of this transistor Q1 is connected to a connected point of the inversion input terminal of the operational amplifier 11 and the input current source 12. To a collector of the transistor Q1, a bias voltage VCC is applied. A base-emitter voltage VBE of the transistor Q1 does not depend on a variance of a current amplification factor beta, and a log converting circuit which is not influenced by the variance of beta is obtained. |
