Hello,

I need output current ~10 uA-30 mA and input voltage should be 0-5 V. I can build U/I converter with an op-amp and 150-ohm resistor, but it means that I get 10 uA for 1 mV.
Is there an easy way to get 10 uA on the higher value of input voltage (e.g. 100 mV)? For example some nonlinear element, or threshold. Because 1mV is a small value.

Thanks in advance for any suggest

 

I don't know if you can do it with a single device. Your range covers about 2.5 decades. I'm thinking it might require some kind parallel control with a coarse and a fine adjustment. Non-linear will probably not work well. As you may or may not know adjusting anything non-linear is more than a bit tricky.

 

Here's a non-linear approach, but it would not be very consistent/reproducible, because of the temperature dependence of the diode response. The two yellow traces are for 0C and 30C respectively.

 

Good luck with controlling that tiger by the tail at the low end of the range. Hope you have a STEADY hand.

 

Indeed. I agree that, for good control, multiple ranges would be needed; 1 linear decade per range tops.