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 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 voltage control current source circuit that generates a differential current signal based on a differential voltage in which the difference between the voltage of the amplitude detection signal and the voltage of the amplitude reference signal is corrected according to an output amplitude setting signal, and a variable capacitance circuit that is connected with output of the voltage control current source circuit, has a capacitance value set according to the output amplitude setting signal, and is charged and discharged according to the differential current signal. The gain control circuit generates the control signal according to a charging voltage of the variable capacitance circuit.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が出力振幅設定信号に応じて補正された差分電圧に基づいて差分電流信号を生成する電圧制御電流源回路と、電圧制御電流源回路の出力に接続され、出力振幅設定信号に応じて設定される容量値を有し、差分電流信号によって充放電される可変容量回路と、を備え、利得制御回路は、可変容量回路の充電電圧に応じて制御信号を生成する。【選択図】図２