| 摘要 |
PURPOSE:To detect the intensity of a signal without giving effect on the operation of an amplitude limiting amplifier, by rectifying an output of a differential amplifier constituting the amplitude limiting circuit with two full-wave rectifier transistors (TRs) and a smoothing capacitor and inputting the rectified output to a comparator. CONSTITUTION:Amplitude limiting amplifier circuits 271-274 comprise differential amplifiers A1-A4, and level shift circuit B1-B4, and one of them, e.g., an output of the differential amplifier B3 of the circuit 273 is applied to a base of full-wave rectifier TRs Q7, Q8. The collectors and emitters of the TRs Q7, Q8 are connected respectively in common, the smoothing capacitor C1 is connected to the emitter and a DC voltage in response to the signal intensity obtained across the C1 is applied to the base of a TR Q9 of the comparator comprising the TRs Q9, Q10, and a reference voltage is applied to the base of the Q10. The output of the comparator is obtained at a current mirror circuit comprising TRs Q11, Q12 and drives a signal intensity meter 33 via a TR Q13. |
