Basic Amplifier Block

What's the Ideal vs. Actual Output?

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IDEAL AMPLIFIER

Here's the Ideal Output equation with gain (K) and offset (Voffset).

You can think of this mathematically as the classic slope (m) and intercept (b) or shift of a line.

You might have seen other terms too!

Check out the equations of the Ideal and Actual blocks.

The errors are defined as

∆K - Gain Error
- change in Gain from ideal (K).
- also called Slope, Span Error
∆Voffset - Offset Error
- change in offset from ideal (0V)
- also called Intercept, Zero Error

Often amplifiers are designed with zero offset (Voffset = 0V) for 0V in, 0V out.
Now the Ideal and Actual (with errors) equations look like this:

Check out the plots of both Ideal (GRN) and Actual (RED) output.

Play in the Excel file - modify values, see what happens!
Right Click on the filename, select "Save link as...".

Excel File: Circuit_Block_with_Errors_1.xlsx

Signal Gain

Start with no errors: ∆Voffset=0 and ∆K/K=0. The Ideal and Actual outputs (and plots) should be equal.
Add an Offset Error, ∆Voffset = 1.0. What happens to the Actual output plot?
Add a Gain Error, ∆K/K = 20%. How does it impact the Actual output plot?

Check out the analog design power tool - Sensitivity Analysis.