TRANSIMPEDANCE AMPLIFIER CIRCUIT

• Main Author: SUGIMOTO YOSHIYUKI
• Format: Patent
• Language: English; Japanese
• Published: 11.11.2022
• Subjects: BASIC ELECTRONIC CIRCUITRY; CONTROL OF AMPLIFICATION; ELECTRICITY

To provide a transimpedance amplifier circuit that prevents fluctuations of an AGC band due to amplitude setting.SOLUTION: A transimpedance amplifier circuit comprises: an amplifier circuit that amplifies an input current signal and converts it into a voltage signal according to a first gain set according to a control signal; and a gain control circuit that generates the control signal according to the amplitude of the voltage signal. The gain control circuit includes a detection circuit that generates an amplitude detection signal according to the amplitude of the voltage signal, a setting circuit that generates an amplitude reference signal according to a reference voltage, a differential voltage generation circuit that corrects the difference between the voltage of the amplitude detection signal and the voltage of the amplitude reference signal according to an output amplitude setting signal to generate a differential signal, a voltage control current source circuit that amplifies the voltage difference of the differential signal to generate a differential current signal according to a second gain set according to the output amplitude setting signal, and a capacitive element that is charged and discharged according to the differential current signal. The gain control circuit generates the control signal according to the charge voltage of the capacitive element.SELECTED DRAWING: Figure 2 【課題】振幅設定によるＡＧＣ帯域の変動を抑えるトランスインピーダンス増幅回路を提供する。【解決手段】トランスインピーダンス増幅回路は、制御信号によって設定される第１利得に応じて入力電流信号を増幅して電圧信号に変換する増幅回路と、電圧信号の振幅に応じて制御信号を生成する利得制御回路と、備え、利得制御回路は、電圧信号の振幅に応じて振幅検出信号を生成する検出回路と、基準電圧に応じて振幅基準信号を生成する設定回路と、振幅検出信号の電圧と振幅基準信号の電圧との差分を出力振幅設定信号に応じて補正して差動信号を生成する差分電圧生成回路と、出力振幅設定信号によって設定される第２利得に応じて、差動信号の電圧差を増幅して差分電流信号を生成する電圧制御電流源回路と、差分電流信号によって充放電される容量素子と、を備え、利得制御回路は、容量素子の充電電圧に応じて制御信号を生成する。【選択図】図２