| 摘要 |
PURPOSE:To obtain a demodulated output without distortion by forming a signal in-phase to a carrier of an AM signal and a phase difference of 90 deg. thereto and applying the signal to the 1st and 2nd sample-and-hold circuits so as to apply orthogonal demodulation. CONSTITUTION:A PLL circuit consists of a phase comparator 11, an LPF 12, a voltage controlled oscillator 13, and 1/2 frequency dividers 14, 15, and a signal in phase and having a phase difference of 90 deg. is obtained respectively from frequency dividers 15, 16. The signal is fed to switches 19, 20 of the 1st and 2nd sample-and-hold circuits via differentiation circuits 17, 18. A lead circuit comprising a capacitor 23 and a resistor 24 is connected to the 1st sample-and-hold circuit and a lag circuit comprising a resistor 25 and a capacitor 26 is connected to the 2nd sample-and-hold circuit. Outputs of the 1st and 2nd sample-and-hold circuits are summed via resistors 27, 28 and the result is outputted. |
