Comments on Is a current-dependent current source and a current mirror the same thing?
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Is a current-dependent current source and a current mirror the same thing?
I have a 4-20 mA digital air pressure regulator which is controlled by and reports its pressure by being the current sink in two independent 4-20 mA current loops.
Our control system utilizes Analog Devices AD4111 ADC which itself sinks current.
I've ran into numerous roadblocks in trying to develop a converter or circuit to allow us to adapt to this regulator which sinks instead of sources current. For example, we've unsuccessfully attempted to add a simple opamp + BJT circuit to act as a repeater of sorts.
Researching this further, I've been trying to determine what the correct terminology would be for a circuit that fulfills this purpose.
Would a "current-dependent current source" (CDCS?) be the correct circuit for this? (I've also seen "current-controlled current source (CCCS).) Is a "current mirror" the same thing? Does the terminology change when the controlling-side current is sinked (sunk?) by an external device versus within the CDCS itself?
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It's not clear that the problem is. It seems you want to interface to this "digital air pressure regulator" via two 4-20 mA current loops.
For reading the output, it should be as simple as a 24 V power supply with a resistor in series. A 250 Ω resistor, for example, will give you a 5 V signal at full scale.
To drive the input, it seems all you need it a 20 mA controlled current source or sink, with possibly another 24 V power supply depending on what's already available in your system. This could be as simple as a FET source follower driven by an opamp to regulate the voltage across the source resistor. I can go into more details once you show a block diagram and otherwise clarify your setup.
As for the title question (which seems completely different from the actual question), a current mirror is one example of a current-controlled current source, but not all current-controlled current sources are current mirrors.
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