| 摘要 |
PURPOSE:To obtain an operational amplifier that has high input resistance without increasing the number of DC amplification stages while facilitating the selection of the resistance for determining an amplification factor with an attenuation factor of noises, by providing an operational amplifier and an inverting amplifier that inverts and amplifies its output. CONSTITUTION:Operational amplifier 10 and inverting amplifier 20 that inverts and amplifies the output of operational amplifier 10 are provided. To the inverted input terminal of operational amplifier 10, the output of operational amplifier 10 is applied after being voltage-divided by resistances 18 and 14 and to the uninverted input terminal, the output of inverting amplifier 20 is applied via capacitor 12 as well as input signal e1 passed through resistance 16, so that output signal E0 will appear at the output terminal of operational amplifier 10. In the above-mentioned constitution, if the input resistance of operational amplifier 10 is not sufficient, resistance values r2 and Rf of resistances 18 and 14 have the resistance ratio from a required amplification factor, so that resistance values of resistances 18 and 14 can freely be selected in themselves. Resistance 16 does not exert any influence on a DC input-output relation at all. |
