| 摘要 |
PURPOSE:To obtain a constant gain and phase characteristic from a low frequency to a high frequency by detecting the quantity based on phase transition and feeding back the quantity to an operational amplifier. CONSTITUTION:A variable gain control circuit 2, n-set of analog switches S1-Sn, operational amplifiers 3, 4, 5, an input resistor RC, n-set of gain selection feedback resistors RE1-REn, and resistors RF, RG and RH are provided, one terminal of the analog switches S1-Sn, is connected to a non-inverting terminal of the operational amplifier and the other terminal is connected to a mutual connecting point of the resistors RE1-REn connected in series. When no phase difference exists between an input signal and an output signal, two signals at an adder means become signals of inverted phase accurately, and nothing is caused at the output, but when a phase difference is generated, a signal based on said phase difference is outputted by the adder means, the signal is given to the non-inverting input terminal of the operational amplifier, which acts like making the input signal coincident with the output signal.
|
