Optical Automatic Gain Control Circuit

Abstract

The present invention relates to an optical automatic gain control circuit. Most of the usual automatic gain control circuits are realized by controlling the attenuation of the PIN diode. This kind of circuit is low in cost, but due to the nonlinearity of the PIN diode, the control range is small and the accuracy is low; when the received power changes, the control When the MCU in the circuit sends an adjustment instruction to the digital control attenuator, because the internal adjustment of the digital control attenuator is step-by-step, the electronic pulse will interfere with the transmission signal, and bright spots or bright lines will appear on the screen of the user terminal, and the dynamic The range is small. The optical automatic gain control circuit includes an operational amplification unit and a radio frequency broadband network matching unit, and is characterized in that it also includes a photoelectric conversion and receiving power detection unit, an MCU control unit, and a gain-adjustable radio frequency broadband amplification unit. The automatic gain control circuit of the invention has high control precision and wide dynamic range.

Description

technical field [0001] The invention belongs to the technical field of cable TV transmission equipment and relates to an optical automatic gain control circuit. Background technique [0002] In the optical receiver of cable TV transmission equipment, most of the usual automatic gain control circuits are realized by controlling the attenuation of PIN diodes. This kind of circuit is low in cost, but due to the nonlinearity of PIN diodes, the control range is small and the accuracy is low. ; The other is realized by single-chip microcomputer and numerical control attenuator. The controllability of this scheme is better than that of PIN diode, but when the received power changes, when the MCU in the control circuit sends an adjustment command to the numerical control The internal adjustment of the attenuator is step-by-step, and the electronic pulse will interfere with the transmission signal, and bright spots or bright lines will appear on the screen of the user terminal, and t...

AI Technical Summary

Problems solved by technology

[0002] In the optical receiver of cable TV transmission equipment, most of the usual automatic gain control circuits are realized by controlling the attenuation of PIN diodes. This kind of circuit is low in cost, but due to the nonlinearity of PIN diodes, the control range is small and the accuracy is low. ; The other is realized by single-chip microcomputer and numerical control attenuator. The controllability of this scheme is better than that of PIN diode, but when the received power changes, when the MCU in the control circuit sends an adjustment command to the numerical control The internal adjustment of the attenuator is step-by-step, and the electronic pulse will interfere with the transmission signal, and bright spots or bright lines will appear on the screen of the user terminal, and the dynamic range is small

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