| 摘要 |
PURPOSE:To achieve high linearity and high S/N, by charging/discharging a given charge to a capacitor with a signal in FM modulation. CONSTITUTION:When a signal in frequency (f) is applied to a limiter 1, the output is a rectangular wave and applied to an amplifier 6. The noninverting and inverting output of the amplifier 6 are applied to switching elements SWs 8, 9, and when they are at high level, the SWs 8, 9 are turned on. When the SW8 is turned on, the SW9 is turned off and a capacitor 10 is charged. Then, when the SW9 is turned on, the SW8 is turned off, and the charge in the capacitor 10 is discharged to an input resistor 13. This current flows to a feedback resistor 12. Since the gain of the amplifier 11 is greater, the output VAMP of the amplifier 11 is as expressed in equation (9), and the average output VOUT is obtained in the relation of equation (11) by applying this output to a low-pass filter 5. That is, the (f) and the VOUT have a relation of proportion. |
