AMPLIFICATION CIRCUIT

• Main Authors: SUGIMOTO YOSHIYUKI, TANAKA KEIJI
• Format: Patent
• Language: English; Japanese
• Published: 11.06.2020
• Subjects: BASIC ELECTRONIC CIRCUITRY; CONTROL OF AMPLIFICATION; ELECTRICITY

To provide an amplification circuit capable of reducing a temperature dependency of a gain.SOLUTION: An amplification circuit 15 comprises: a differential circuit 53 that generates a differential current signal in accordance with a differential input signal; and a control current source 55 that supplies a control current IDAC so that a transconductance of a field-effect transistor 84 becomes constant. In a variable resistance circuit 58 of the differential circuit 53, a source and a drain of a field-effect transistor 83 are electrically connected to emitters of transistors 56 and 57, respectively. A source of the field-effect transistor 84 is electrically connected to a connection point P between a resistance element 81 and a resistance element 82 connected between the emitters of the transistors 56 and 57 in series and having mutually equal resistance values. A gate of the field-effect transistor 83 and a gate and a drain of the field-effect transistor 84 are electrically connected to a control terminal TC, which receives the control current IDAC, in common.SELECTED DRAWING: Figure 1 【課題】利得の温度依存性を低減可能な増幅回路を提供すること。【解決手段】増幅回路１５は、差動入力信号に応じて差動電流信号を生成する差動回路５３と、電界効果トランジスタ８４のトランスコンダクタンスが一定となるように制御電流ＩＤＡＣを供給する制御用電流源５５と、を備え、差動回路５３の可変抵抗回路５８では、電界効果トランジスタ８３のソース及びドレインがトランジスタ５６，５７のエミッタにそれぞれ電気的に接続され、トランジスタ５６，５７のエミッタの間に直列に接続された互いに等しい抵抗値を有する抵抗素子８１及び抵抗素子８２の接続点Ｐに電界効果トランジスタ８４のソースが電気的に接続され、電界効果トランジスタ８３のゲートと、電界効果トランジスタ８４のゲート及びドレインとが、制御電流ＩＤＡＣを受ける制御端子Ｔｃに共通に電気的に接続される。【選択図】図１