| 摘要 |
PURPOSE:To set the gain freely and simply, by providing plural operating circuits multiplying a certain coefficient with an output signal, synthesizing the outputs of a selected operating circuit and feeding back the synthesized result to an input. CONSTITUTION:An output VO of an operational amplifier 3 to which an input signal Vi is applied, is supplied to operating circuits K1-Kn multiplying coefficients k1-kn via switches S1-Sn. Further, the output of each operating circuit is summed at an adder M and applied to an input of the amplifier 3 as a feedback signal Vf. The gain G of this circuit is G=VO/vi=1/(k1+k2+...+kn). Thus, the setting of the gain G is done by selecting the coefficients k1-kn with the plural switches S1-Sn. The switches S1-Sn are switched with an external signal in this way, allowing to set the gain freely and simply. |
