Electronic circuit comprising a current mirror integrated of the variable gain and advantages of the control of the gain of a current mirror

摘要

The circuit uses a pair of bipolar transistors (T1,T2), of same polarity, on the integrated circuit substrate, connected as a current mirror of gain I2/I1, depending on their individual characteristics. The circuit (T3,T4,11a,11b) applies a potential difference between the emitters of the first pair (T1,T2). This is varied by a control signal (S) to vary the gain. The transistor bases (B1,B2) may be connected together and their emitters (E1,E2) to a common voltage (10). The first transistor (T1) may be diode connected, with collector (C1) to base (B1), so that second transistor (T2) collector (C2) current (I2) varies as the first (T1,C1,I1). Modulation transistor (T3,T4) emitters (E3,E4) may be connected between the first transistor emitters and the common voltage.