| 摘要 |
PURPOSE:To make it possible to measure under the condition of constant output voltage without variation in the condition due to a measured frequency in the measurement of open voltage gain for an operational amplifier by utilizing the operational amplifier for measurement and making measurement without using a capacitor in a feed back circuit. CONSTITUTION:The output terminal 4 of an operational amplifier 1 to be measured is connected to the non-reversible input terminal 12 of an operational amplifier 17 to be used for measurement, and feed-back is provided to a reversible input terminal 3 of the amplifier 1 through resistors 16 and 15 from the output terminal 14 of the amplifier 17. When signal voltage VX is input to the reversible input terminal 13 of the operational amplifier 17 for measurement by using an alternating current signal source 5, voltage VX develops at the output terminal 4 of the operational amplifier 1 to be measured. Supposing that alternating current voltage gain in AVD of the amplifier 1, VX/AVDI is outputted at the reversible input terminal 3, and VY/AVDI is outputted at the output terminal of the amplifier 17, and voltage gain is expressed as AVDI=(VX.R16)/ (VY.R16). It is possible, therefore, to measure with the output voltage of the calculation amplifier 1 to be measured with previous variation in the conditions due to frequency. |
