# current controlled current source

## Objective

I am trying to build a gain-of-1 current controlled current source (current mirror) that is less sensitive to resistor value variation. The designs i have been making are highly resister dependent, as I am using shunt resisters.

## Specifications

• On the input and output sides, I have 24vdc source
• The input side control current is well behaved.
• Input and output safe-operating-range must include 4mA-20mA
• The load is 500 ohms

## Current Approach

This is the circuit I have been playing with. The circuit is very dependent on the 50 ohm resisters.

I have looked at a current mirror, but the matched mosfets I can get only have a VDS of 10V, when given a 24vdc supply, bad things can happen.

• a bipolar transistor is a current controlled current source. You need to be clearer with specs. Mar 26 '13 at 20:13
• What is the range of the input current? What voltage range must the output current be correct over? Does this device need to source current, sink it, or both? Mar 26 '13 at 20:28
• input current is 4ma to 20ma. The output has a 24vdc supply. This device needs to source 4ma to 20ma based on the input. Mar 26 '13 at 20:36
• Please answer the questions. Your concept of the circuit to meet the specs is of little use at best since it doesn't work. Tell us what you want to accomplish, not how you think it should be accomplished. Mar 26 '13 at 20:42
• A piece of wire will supply 4-20 mA out with 4-20 mA input... what are your input and output voltage compliance requirements? Mar 26 '13 at 20:44

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