electrical4u.com logo Home MCQ Engineering Calculators Videos Basic Electrical Circuit Theories Electrical Laws Materials Batteries Illumination Generation Transmission Distribution Switchgear Protection Measurement Control System Utilities Safety Transformer Motor Generator Electrical Drives Electronics Devices Power Electronics Digital Electronics Biomedical Instrumentation

Summing Amplifier or Op Amp Adder

Published on 24/2/2012 & updated on 5/9/2018
HOME / CIRCUIT THEORY / OP-AMP
An op amp is an amplifier. But an op amp can also perform summing operation. We can design an op amp circuit to combine number of input signals and to produce single output as a weighted sum of input signals.
Summing amplifier is basically an op amp circuit that can combine numbers of input signal to a single output that is the weighted sum of the applied inputs.

The summing Amplifier is one variation of inverting amplifier. In inverting amplifier there is only one voltage signal applied to the inverting input as shown below, inverting amplifier This simple inverting amplifier can easily be modified to summing amplifier, if we connect several input terminals in parallel to the existing input terminals as shown below. summing amplifier

Related pages
Summing Amplifier or Op Amp Adder

Here, n numbers of input terminal are connected in parallel. Here, in the circuit, the non-inverting terminal of the op amp is grounded, hence potential at that terminal is zero. As the op amp is considered as ideal op amp, the potential of the inverting terminal is also zero. So, the electric potential at node 1, is also zero. From the circuit, it is also clear that the current i is the sum of currents of input terminals.

Therefore, Now, in the case of ideal op amp the current at the inverting and non-inverting terminal are zero. So, as per Kirchhoff Current Law, the entire input current passes through the feedback path of resistance Rf. That means, From, equation (i) and (ii), we get, This indicates that output voltage v0 is weighted sum of numbers of input voltages.

Example of summing Amplifier

Let us calculate the output voltage of 3 inputs summer or summing amplifier, circuit as shown below, Here, as per equation of summing amplifier,




Please Rate this Article
3
⚑ 2 total
5
4
3
2
1


New Articles
More Articles on Circuit Theory
Circuit and NetworkCircuit TheoremCircuit AnalysisTwo Port NetworkRL CircuitMatrixRLC Circuit
Articles Categories
Write for Us
Home
Basic Electrical
Electric Transformer
Electric Generator
Electric Motor
Electrical MCQ
Engineering Calculators
Video Lectures
Electrical Generation
Electric Transmission
Switchgear
Electric Protection
Electrical Measurement
Electronics Devices
Power Electronics
Digital Electronics