Re: Opamp offset voltage problem
- From: Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@xxxxxxxxxxx>
- Date: Sun, 04 Feb 2007 11:43:30 -0500
kell wrote:
On Feb 1, 10:36 pm, amy_burton2...@xxxxxxxxx wrote:you know, back in the old days! i think it is the 741? pins 1 and 8
Hi! I want to measure the offset voltage of an opamp. First, I
configure the opamp in an unity gain buffer and measure the output.
Here's another way that might be more reliable.
To measure offset:
ground the non-inverting input; run a pot from the op-amp output to
ground; connect the pot wiper to the inverting input. Measure the
output voltage. Calculate offset at the input as output voltage times
1+(R2/R1), where R1 is the grounded side of the pot and R2 is the side
connected to the op amp output.
The offset voltage is 64.16uV. Then, I applied this voltage to the
non-
inverting input of the opamp. When I simulate it again, instead of
getting 0V at the output, I get 464.29mV.
Is the op amp open loop? I don't think that's how you null them out.
There are nulling cicuits here:
http://www.google.com/search?hl=en&q=op+amp+circuit+collection
gave you nulling inputs you could put a pot on with the wiper to
- to fix that little problem. :)
--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
.
- References:
- Opamp offset voltage problem
- From: amy_burton2007
- Re: Opamp offset voltage problem
- From: kell
- Opamp offset voltage problem
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