| 摘要 |
PURPOSE:To prevent the increase in noise attended with an increase in a DC component of an input signal and to suppress the rapid reduction in the amplification factor due to the saturation of the circuit by adding a current mirror circuit on the way of a feedback resistor. CONSTITUTION:An area Z1 of a differential amplifier (amplifier A1) is a feedback part of the circuit and includes feedback resistors Rf1, Rf2 and a current mirror circuit C having NPN transistors(TRs) Q1, Q2. The feedback quantity to an input terminal of the amplifier A1 is increased to decrease the amplification factor when the DC component of the input signal is increased by adding the current mirror circuit C on the way of the feedback resistors Rf1, Rf2, then increase in noise is prevented and the rapid reduction in the amplification factor due to the saturation in the circuit is suppressed. |
