Electrical – Problem with accuracy of AD633 multiplier

multiplierprecisiontolerance

I have 3pcs of AD633 chips, and the accuracy should be ±1% (typical), ±2% (max) according to datasheet.

I wired it like this:

enter image description here

I tried several input voltages, but it seems, that output is still way out of tolerance.
For example:

IN1=7.008V
IN2=2.003V
OUT=1.4537V

Output should be precisely 1.4037V. But it's 3.5% out.
All 3 my chips are out of tolerance (up to 5%).

I don't know if there is problem in my circuit?
Or problem is that all of those chips are out of tolerance? (bought from China)

Best Answer

I made very basic error. Problem was in quality of ±12V power source. After I added some capacitors, precision of those multipliers improved dramatically. enter image description here

Precision is within 1% now.

IN1=7.004V
IN2=2.0046V
OUT=1.4082V

So, now it is out by 0.3%. That is better :)

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