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Yeah, right.Ron please tell me what needs to be done.I will learn better this way.
Below is a block diagram of the idea I mentioned earlier. If Rload is low (you said <5Ω, IIRC), you shouldn't need a buffer amplifier, and you definitely won't need an output level shifter.This is just a small part of the project and i never thought it would be so tough.
I hope you wont mind
Thanks and regards
If I understand your calibration procedure, when you subtract the cal value, that will (I think) also subtract all offset (but not gain) errors in the measurement chain. Offsets will still show up in the initial current magnitude measurement, so if that's important, you will need to use low-offset amplifiers. For example, 50mA will give you 50mV across the 1Ω sense resistor. 1mV of offset in the input amplifier will cause 1mA of error. You can't compensate for that unless you are using a high-precision, low drift sense resistor.Reading your post
..just checking what you meant by i being correct about offset in output amplifier..Does it mean that the actual measured voltage in microvolts(above some millivolts) is above the offset voltage so any opamp would do?(although i will use a precise opamp)..Is that correct?
Meanwhile will check the link u posted
thanks for your time
In my current sink schematic, I added a frequency compensation network consisting of resistors and capacitors. I determined their values empirically, by simulations. You may need similar compensation in the current source circuits to prevent ringing or oscillation.Hello Ron
i have said earlier that for the current magnitude measurement i am using OP07 since the accuracy required is below the offset stated by OP07.I will dig some p-channel mosfets and test the source version today.
The sense resistor i am using is not precise for now.But WILL sure use a precise one actually.I am getting a board painted for this today since on a general purpose board i have lots of wires and links which must be adding to noise and offsets.
You have been very helpful..