From WikiChip
Analog Adders

Not to be confused with Digital Adders.

In analog computers addition is usually done using an operational amplifier, although other methods such as resistive adder circuit are possible. Additionally CMOS analog adders are another method used when dealing with natural signals.

Summing Op-Amp[edit]

summing op amp.svg
Main article: Summing amplifier

Given Equation upper G equals normal infinity , the sum of the currents at the summing junction is 0.

Equation sigma-summation Underscript i equals 1 Overscript n Endscripts StartFraction upper V Subscript i Baseline Over upper R Subscript i Baseline EndFraction equals minus StartFraction upper V Subscript out Baseline Over upper R Subscript upper F Baseline EndFraction

Given Equation x equals StartFraction upper R Subscript upper F Baseline Over upper R Subscript i Baseline EndFraction , then

Equation minus upper V Subscript out Baseline equals sigma-summation Underscript i equals 1 Overscript n Endscripts x Subscript i Baseline upper V Subscript i

Input are usually configured using a set of coefficient potentiometers.

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