Precise automatic gain control circuit

Abstract

The invention discloses a precise automatic gain control circuit, relates to the technical field of automatic gain control in a transimpedance amplifier under an integrated circuit, and aims to solvethe problem that the output swing of a common automatic gain control circuit cannot be adjusted due to temperature and process influences, so that the overall performance of a TIA is reduced. The circuit comprises an output buffer, a peak-to-peak value detection circuit, a resistor R1, an amplifier A0 and a capacitor C1. The input end of the output buffer is connected with the output end of the trans-impedance amplifier (TIA); two output ends of the output buffer are respectively connected with a positive voltage output end OUTP and a negative voltage output end OUTN, and are simultaneously connected with two input ends of the peak-to-peak value detection circuit; the output end of the peak-to-peak value detection circuit is connected with one end of the resistor R1; the other end of the resistor R1 is connected with the inverting input end of the amplifier A0 and one end of the capacitor C1; the in-phase input end of the amplifier A0 is connected with a comparison threshold voltage VSET, and the other end of the capacitor C1 is connected with the output end of the amplifier A0 and a feedback resistor RF resistance value control signal line at the same time.

Description

technical field [0001] The invention belongs to the technical field of automatic gain control in transimpedance amplifiers under integrated circuits, and relates to a precise automatic gain control circuit. Background technique [0002] At the receiving end of the optical fiber communication integrated circuit, it is necessary to convert the optical signal into a current signal through a photodiode (PD), and then convert the current signal into a voltage signal through a transimpedance amplifier (TIA). Under the condition that the gain of the transimpedance amplifier (TIA) is constant, when a large current is input, the non-linear problem of the circuit becomes very serious. Therefore, an automatic gain control circuit (AGC) is introduced into the transimpedance amplifier. When the transimpedance amplifier inputs a large current, it can automatically reduce the circuit gain to keep the output voltage range unchanged. [0003] figure 1 The structure of a commonly used autom...

AI Technical Summary

Problems solved by technology

[0010] The purpose of the present invention is to solve the problem that the output swing of the commonly used automatic gain control circuit cannot be adjusted due to the influence of temperature and process, resulting in a decrease in the overall performance of the TIA, and provides a precise automatic gain control circuit

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