| 摘要 |
PURPOSE:To attain the advantage of hybrid integrated circuit by constituting the circuit where a coupling capacitor is inserted between an HPF circuit and a rectifier smoothing circuit so as to make an offset voltage at a BPF output point constant and improve the recognizing rate. CONSTITUTION:The coupling capacitor 61 is inserted between the HPF circuit and the rectifier smoothing circuit. In taking a + terminal input point of an amplifier circuit 25 as 1, an output point of the amplifer circuit 25 as 2, an output point of the BPF as 3, an output point of the coupling capacitor 61 as 4, and a resistance value of a resistor 24 as R2, although an input voltage at the + terminal input point of the amplifier circuit 25 is fluctuated at each channel because each resistance value differs more or less from each channel and the R2 of (Ib+R2) is different and a voltage at an output point 2 of the amplifier circuit 25 is fluctuated at each channel, the DC component is not transmitted because of the capacitor 61, then an output point 4 of the capacitor 61 reaches a prescribed voltage and each offset voltage of an output point 3 of the BPF is also a constant value. |
