Input signal intensity display circuit for avalanche photodiode (APD) in light receive module

Abstract

The present invention discloses an input signal intensity display circuit for an avalanche photodiode (APD) in a light receive module. The input signal intensity display circuit comprises a transimpedance amplifier output voltage sampling module, a virtual transimpedance amplifier, a transimpedance error amplifier and a current proportion amplifier. The transimpedance amplifier output voltage sampling module is used for sampling an output signal of a transimpedance amplifier so as to obtain an output common mode direct current voltage related to the input signal intensity of the APD. The virtual transimpedance amplifier is used for copying the transimpedance amplifier so as to obtain a circuit the same as the transimpedance amplifier and obtain an output reference voltage when the input signal intensisty is zero. The transimpedance error amplifier is used for converting errors of the output common mode direct current voltage and the output reference voltage, so as to obtain a current signal equivalent to the input current of the APD. The current proportion amplifier is used for performing proportional mirroring on the output current of the transimpedance error amplifier, so as to obtain an input signal intensity display current. According to the input signal intensity display circuit, the input signal intensity of the APD can be displayed inside a chip; a manner of sampling and comparing the output signal of the transimpedance amplifier is adopted, thereby having a small impact on input of the transimpedane amplifier; and peripheral system is simple to use.

Description

technical field [0001] The invention relates to the technical field of optical communication, in particular to an input signal strength display (RSSI, ReceiveSingalStrengthIndicator) circuit used for an APD in an optical receiving module. Background technique [0002] In the field of optical communication, the transimpedance amplifier is usually used as the preamplifier of the receiver, such as figure 1 As shown, it is the schematic diagram of the input signal strength display circuit of the traditional APD (avalanche photodiode), which mainly samples from the negative electrode of the avalanche photodiode, so as to display the amplitude of the input signal outside the chip. The input signal strength is displayed, and this circuit needs to add a pair of mirrored triode circuits in the peripheral application circuit, which makes the peripheral system application complicated. [0003] In view of this, there is an urgent need to provide an input signal strength display circuit...

AI Technical Summary

Problems solved by technology

[0002] In the field of optical communication, the transimpedance amplifier is usually used as the preamplifier of the receiver, such as figure 1 As shown, it is the schematic diagram of the input signal strength display circuit of the traditional APD (avalanche photodiode), which mainly samples from the negative electrode of the avalanche photodiode, so as to display the amplitude of the input signal outside the chip. The input signal strength is displayed, and this circuit needs to add a pair of mirror transistor circuits in the peripheral application circuit, which makes the peripheral system application complicated

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