Integrated bipolar current controlled resistor for gain control - has two parallel connected transistors with bases joined to receive common control current

摘要

The resistor comprises two bipolar transistors (T1,T2) of the same type, NPN or PNP. Each signal terminal (A,B) of the resistor is a connection between the emitter of one transistor (T1,T2) and the collector of the other. The resistance controlling terminal (C) is the connection between the two bases. The transistor (T1) which has its emitter grounded has a smaller emitter surface than the other. Each transistor (T1,T2) may have an additional emitter which is connected to the bases. The controlling current (i) is applied to the bases and additional emitters. The resistor has a linear resistance characteristic for a high range of voltages, both negative and positive.