| 摘要 |
PURPOSE:To extend a demodulation frequency band and the range of linear detection, by converting the frequency modulation wave to a square wave and by averaging the square wave to obtain the average value as the detection output after subtracting the waveform of a fixed area from the waveform of this square wave. CONSTITUTION:The frequency modulation wave is subjected to amplitude limiting through amplitude limiting amplifying circuit 1 and is subjected to waveform shaping through waveform shaping circuit 2 and is converted to a square wave. This square wave is not only converted to a saw-tooth wave through saw-tooth wave generating circuit 3 but also has the amplitude limited to be converted to a trapezoidal wave where the waveform area is changed in proportion to the frequency of the frequency modulation wave. This trapezoidal wave is caused to pass through low-pass filter 4 to take out the average value, and this average value is set to the detection output. |
