| 摘要 |
PURPOSE:To enable to perform broad band amplification having the gain selection functions less in the points of adjustment and in drift, by comparing the input signal with the difference signal voltage between the output terminals by means of the first operational amplifier and performing negative feedback the difference to the amplifying transistor. CONSTITUTION:The operational amplifiers 61, 68 and 80 are placed between the signal input terminal 1 and signal output terminals 2, 3. Further, the amplifier 68 inputs the output of the output terminals 2 and 3, amplifies the potential difference between the output terminals 2 and 3 and feeds it to the operational amplifier 80. This amplifier 80 compares the input signal with the difference signal voltage between the output terminals 2 and 3, and the difference is negative-fed-back to the base of the amplifying transistor Tr28. This negative feedback compensates the variation in the potential difference between the terminals 2 and 3 accompanied with the gain selection and with the drift due to the amplifying circuit consisting of Tr27...34. Thus, the broad band amplification having the gain selective functions less in the points of adjustment and in the drift can be made. |
