Dependent Sources

A dependent source is either a voltage or a current source which is dependent upon another value within the circuit, usually another voltage or current. Typically, these are used in circuit modelling and analysis. There are four main types of such sources.

Voltage-controlled voltage source (VCVS)

This is a voltage source whose value is controlled by another voltage elsewhere in the circuit. Its output will typically be given as Vo = AVc, where A is a gain term and Vc is a control voltage. An example of a VCVS may be an idealized amplifier1 , where A is the gain of the amplifier.

Current-controlled voltage source (CCVS)

This is a voltage source whose value is controlled by a current elsewhere in the circuit. Its output is typically given as Vo = AIc, where A is a gain term and Ic is a control current.

Voltage-controlled current source (VCCS)

This is a current source whose value is controlled by a voltage elsewhere in the circuit. Its output is typically given as Io = AVc, where A is a gain term and Vc is a control voltage.

Current-controlled current source (CCCS)

This is a current source whose value is controlled by a current elsewhere in the circuit. Its output is typically given as Io = AIc, where A is a gain term and Ic is a control current.

An example of a CCCS is an idealized bipolar junction transistor2, which may be thought of as a small current controlling a larger one. Specifically, the base current, Ibis the control and the collector current Ic is the output.