| 摘要 |
PURPOSE:To adjust an offset and to suppress its fluctuation by connecting the 2nd differential amplifier in parallel with the 1st differential amplifier amplifying an input signal and adjusting an input DC voltage of the 2nd differential amplifier. CONSTITUTION:An offset adjusting differential amplifier 26 is connected in parallel with a differential amplifier 24 amplifying an input signal fed to input terminals 22A, 22B. A constant bias voltage is set to a base of a transistor (TR)36 by a voltage source 40 in the differential amplifier 26 and a bias voltage as a DC input voltage for offset adjustment is set to a base of a TR34 by a variable voltage source 42. Thus, a desired offset is set by adjusting a variable voltage source 42. Thus, the offset is adjusted freely and the change in the offset is suppressed even if the adjusting current is fluctuated. |
