| 摘要 |
PURPOSE:To ensure the demodulation of the FM signal by giving the differetial amplification to the input signal and then giving ON/OFF to the two MOSFET's with the two outputs of the input signal through the control given to the charge/discharge of the capacitor connected between the two MOSFET's. CONSTITUTION:When switch 12 is turned toward terminal 11 at circuit B, the electric charge is charged to CV1 of capacitor 13 (capacity C). And the charge amount flowing over toward terminal 14 features Q=C(V1-V2) when switch 12 is turned toward terminal 14, and thus the average level features I=(V1-V2)C/T (T: cycle) for the alternating current between terminals 11 and 14. With the replacement with insertion of such circuit B between terminals 3 and 17 of FM detection circuit A, switch 12 corresponds to 5 and 6 of MOSFET's. In other words, the input signal given from input signal source 1 which gave the frequency modulation to the rectangular wave is applied to differential amplifier 4, and the two signals of opposite phases to each other which are the output of amplifier 4 are supplied to the gate. As a result, transistors Tr5, 6 are switched to each other, and the frequency of the frequency modulation wave, i.e., the output DC voltage corresponding to sampling cycle T can be extracted out of load 8 via capacitor 7. |
