| 摘要 |
PURPOSE:To respond quickly to both an increase and decrease in input signal waveform by providing three comparators or more different in threshold level to a circuit which attains the amplitude discrimination and generates a control voltage for an AGC loop and by controlling the charging and discharging of a capacitor in a current supply with outputs of those comparators. CONSTITUTION:Amplitude-discriminating and control-voltage generating circuit DET LF for the AGC circuit controlling siganl amplitude to a fixed value is provided with three comparators CMP1 to CMP3 or more with different threshold levels (alpha), (beta) and (gamma), and change-over switches SW1 to SW3 are controlled by outputs of those comparators CMP1 to CMP3 to control a current form constant current supply nIo for the charging and discharging of capacitor C. Then, the voltage of capacitor C is applied to buffer amplifier BA, output is applied to variable gain amplifier GCA, so that the amplitude discrimination system will be constituted which responds quickly to both an increase and decrease in input signal Vsi waveform. |
