| 摘要 |
PURPOSE:To adjust automatically the duty ratio of an EFM signal, by comparing the integrated output of the EFM signal with a reference voltage to generate a control voltage which sets the slice level of a waveform shaping circuit which generates the EFM signal from an HF signal. CONSTITUTION:An amplifying circuit 3 consists of an operational amplifier 13, a feedback resistance 14 connected to one terminal of the operational amplifier 13 and an output terminal, an output resistance 15, and a capacitor 16, and the terminal voltage of a capacitor 12 is impressed to the + terminal of the operational amplifier 13, and a reference voltage Vf is impressed to the - terminal. The reference voltage Vf is obtained by dividing voltage +5V in a variable resistor 17. The operational amplifier 13 charges the capacitor 16 through the resistance 15 with an output voltage corresponding to the difference between the reference voltage Vf and the terminal voltage of the capacitor 16, and the terminal voltage of the capacitor 16 is impressed to the gate of an FET5 through a resistance 10. |
