# offset voltage calculation (c)

Discussion in 'Homework Help' started by Viktor Vaughn, Apr 25, 2015.

1. ### Viktor Vaughn Thread Starter New Member

Mar 21, 2015
24
0
Hi everyone,

I am having trouble understanding how my professor calculated 12.8mv for the output offset. Attached is the highlighted homework question and my calculations for circuit (c). If anyone can help me better understand this would be great.

Thanks, View attachment 84634 View attachment 84635

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2. ### crutschow Expert

Mar 14, 2008
13,479
3,366
You need to include the temperature effect on the offset but your value looks correct at room temperature for that circuit.

3. ### Viktor Vaughn Thread Starter New Member

Mar 21, 2015
24
0
Ok, so when I add the temperature coefficient it would be 20mv + 10uv(50) = 20.5mv. I can't fathom where he is getting 12.8mv from , unless his calculations are wrong.

4. ### kdillinger Active Member

Jul 26, 2009
141
3
You should double check with your professor regarding the 12.8mV answer. The question as posed is missing information. Offset voltage coefficient (also known as offset voltage drift) is a calculation based off measurements during test. Using drift in a total offset measurement requires a change in temperature to understand its effect. The question simply states 50C.

5. ### Viktor Vaughn Thread Starter New Member

Mar 21, 2015
24
0
Your correct! Im going to ask him about his 12.8mv calculation, because by the text in the book, I cant see any other possibility other than 20.5mv