Amplitude detection and automatic gain control (AGC) circuit

Abstract

The invention relates to an amplitude detection and automatic gain control (AGC) circuit. An input signal is taken from a common-mod circuit and an input signal amplitude detection circuit which are respectively connected with a level-shifting circuit, and the level-shifting circuit is connected with an AGC circuit which is connected with an automatic gain circuit. The amplitude detection AGC circuit mainly has the effects that the AGC circuit can detect the amplitude of the input signal and adjusts an AGC voltage according to an amplitude value thereof to further adjust the gain of a transimpedance amplifier, and a large input signal has little output distortion.

Description

technical field [0001] The invention belongs to the field of optical fiber communication and integrated circuit design, in particular to an amplitude detection automatic gain control circuit. Background technique [0002] Fiber optic communication uses light as the information carrier and optical fiber as the transmission medium. At present, the bottleneck of the development of the optical communication industry. Microelectronic integrated circuits used in optical communication networks mainly include preamplifiers, limiting amplifiers, clock and data recovery circuits, splitters, and multiplexers. Among them, the preamplifier is directly connected with the photodetection device, and the photodetector converts the input light signal into electric current. Because the distance between the signal transmitting end and the receiving end may be very far or very close. This difference in distance is directly reflected in the strength of the optical signal. After the signals of ...

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Problems solved by technology

However, the response of this AGC control circuit is relatively slow, generally taking hundreds of microseconds

And because the change of its common-mode voltage will affect the operating point of the subsequent stage, the post-stage amplifier works in the saturation region, resulting in distortion of the output signal

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