| 摘要 |
PURPOSE:To stabilize the drift characteristics of a low frequency band by a low band amplifier, by connecting the low band amplifier having a low drift characteristic equivalenly in parallel to a high band amplifier which has a differential amplifier with an offset adjusting terminal in the first stage. CONSTITUTION:An input signal Vi coming to an input terminal Ti is given to the base of a transistor (TR)2 of a differential amplifier 12 through a noniversion input terminal t5, and amplifier signals obtained in collectors of TRs 1 and 2 are amplified by a main amplifier 13 and are transmitted to an output terminal To. A low band amplifier 21 amplifies the input signal Vi to cause a light emitting diode 22 to emit the light, and the resistance value of photoconductive element 18 is changed by this light emission. Currents i1 and i2 flowed to TRs 1 and 2 are changed by this change of the resistance value, and amplified signals are superposed and obtained in collectors of both TRs. |
