Electronic – CCVS (current controlled voltage source) in practice

current measurementcurrent-source

In my current project I'll possibly need to deploy a CCVS (Current controlled voltage source). It is transconductance amplifier or converter and many manufacturers offers transconductance amplifier but in form of a VCCS (Voltage controlled current source). In practice I need CCVS with 0.5ohm (or 500mV/A). When using simulation like one in TINA it's easy: there you can choose ideal CCVS and everything works perfect: for let say 5mA of current it's "mirroring" 2.5mV.

Current mirroring using ideal CCVS

I was playing with different current mirror topologies (with 2 to 4 transistors) and the best what I got is predictable "transfer" of 100 ohm, that means for 1mA of the current (Ibias on the picture) 100mV (Vbias). Something that seems to make things more challenging is that emitter is connected to approx. -6V (-15V + 9.1V zener) but this is another story. First I need to get a precise 0.5ohm "mirroring".
My question is how to calculate 0.5ohm current mirror (any topology) that I can use in place of ideal CCVS.

Best Answer

Some background: A device (or circuit) in which the Output Voltage is controlled by the Current i.e. V(I), is a trans-resistance (or trans-impedance).

A device (or circuit) in which the Output Current is controlled by the Voltage i.e. I(V), is a trans-conductance.

What you need is a TIA (TransImpedance Amplifier). Using current mirrors and the voltage on the gate will be very non-linear. To be fair, I am assuming you want something linear, if that is wrong then use transistors.

schematic

simulate this circuit – Schematic created using CircuitLab