# What is an example of a three-terminal current-controlled voltage source?

Dependent sources come in four flavors:

• voltage-dependent current sources (e.g. a FET can act as a VCCS)
• current-dependent current sources (BJT)
• voltage-dependent voltage sources (OpAmp as an example of a linear component)
• current-dependent voltage sources

A resistor can be seen as a special type of CCVS, where the current through the resistor determines the voltage across it.

Is there such a thing as a three-terminal current-controlled voltage source? I guess the equivalent circuit could look like this:

simulate this circuit – Schematic created using CircuitLab

The current at AM1 controls the voltage across R1, measured by VM1. But is there a single, specific component that does the same thing?

• I think your exercise is a pointless. Why? Because you try to find examples of devices which behave as ideal devices. The point of those ideal devices is that they are not real. We use them to model the behavior of real devices. a FET can act as a VCCS not really as a FET is very non-linear and has a finite output impedance, limited output current range etc. We can however model a FET, while it is operating under certain conditions, as a VCCS. Not the other way round. – Bimpelrekkie Nov 26 '18 at 14:27
• @Bimpelrekkie But does a VCCS need to be linear? I'm not looking for ideal devices, but rather for the 'missing component': in an FET, the current is controlled by a voltage. In a BJT, the current is controlled by a current. In an OpAmp, the voltage is controlled by a voltage. That leaves the last combination, which so far I have only seen as a conjunction of several other components. If such a device doesn't exist, doesn't have a special name or is generally never needed in applications, that would also be an answer. – ahemmetter Nov 26 '18 at 14:45
• All these can be made using opamps, including the CCVS: electronics-tutorial.net/analog-integrated-circuits/… So it is not a question of "can I make one?" Yes you can. All that's needed is an Opamp, some resistors and perhaps a MOSFET. – Bimpelrekkie Nov 26 '18 at 14:51
• A Norton amplifier is kinda like a CCVS: mysite.du.edu/~etuttle/electron/elect21.htm – John D Nov 26 '18 at 14:59
• @Bimpelrekkie Thanks! My question though was if such device has a name and exists as a common lumped element, rather than 'if I can make one'. After all, I already showed a quick example in the question, so of course that's possible. To rephrase: does a component exist that directly controls the voltage through an applied current, rather than through the 'conversion' between current and voltage in a resistor? – ahemmetter Nov 26 '18 at 15:20