| 摘要 |
PROBLEM TO BE SOLVED: To allow a circuit to restore quickly from a standby state to a reception state by providing a voltage/current conversion amplifier receiving respectively noninverting and inverting outputs and having a capacitor between both input terminals to the amplifier circuit to feed back an output of the voltage/ current conversion amplifier to an inverting input signal. SOLUTION: A prescribed bias is given respectively to noninverting and inverting inputs. Furthermore, a noninverting output OUT 1 (inverting output OUT2) is connected to a noninverting input (inverting input) of a voltage/current conversion amplifier 104 via a resistor 105(106)(the resistance of both the resistors is selected identically). A capacitor 107 is connected between both the noninverted and inverted inputs of the amplifier 104 and configures a DC voltage feedback low-pass filter together with the resistors 105, 106. The amplifier 104 receives a DC offset produced between the outputs OUT 1 and OUT2 to change a DC bias of the inverted input IN 2 by an output current depending on the DC offset. Thus, the DC offset caused between the outputs OUT1, OUT2 is cancelled. Then the amplitude of the received signal is limited so that a prescribed bias voltage is selected for a center level and a peak voltage is a power supply voltage. |
