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The Transfer Function of the Non-Inverting Summing Amplifier with “N” Input Signals
Sunday, August 9th, 2009Summary:
In a previous article, How to Derive the Summing Amplifier Transfer Function, I deduced the formula for the non-inverting summing amplifier with two signals in its input. But what if we have 3, 4 or an n number of signals? Can we add them all with one amplifier?
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How to Derive the Summing Amplifier Transfer Function
Thursday, July 9th, 2009Summary:
The summing amplifier, or the non-inverting summing amplifier, is an analog processing circuit with the transfer function (the summing amplifier formula as some say) shown in the following equation.
(1)
The first term of the product is the actual summing, while the second term is a gain due to the R3 and R4 resistors. I prefer this [...]
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The Transfer Function of an Amplifier with a Bridge in the Negative Feedback
Friday, July 3rd, 2009Summary:
In allaboutcircuits.com forum an interesting circuit was posted. The question was, how to determine the transfer function, Vout/Vin?
The circuit schematic was drawn as in Figure 1.
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The Differential Amplifier Common-Mode Error – Part 2
Sunday, June 7th, 2009Summary:
When designing a differential amplifier, part of the art is to manage the errors affecting the precision of the circuit. In The Differential Amplifier Common-Mode Error – Part 1 of this presentation I discussed the common-mode error of a differential amplifier. I also showed that, given the circuit in Figure 1, the common-mode voltage can be viewed as V2, when we consider V1-V2 as a signal that rides on top of V2. The same goes for V1, which can be considered the common-mode voltage of the differential amplifier when -(V1-V2) is the signal that rides on top of V1.
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The Differential Amplifier Common-Mode Error – Part 1
Wednesday, May 20th, 2009Summary:
The common-mode voltage can bring errors in the differential amplifier applications. What is the common-mode voltage? The common-mode voltage is the voltage level common to both inverting and non-inverting inputs of the differential amplifier. In many applications, the differential amplifier is used to amplify the difference between two voltages, for later processing, or to isolate a signal from common-mode noise, or to amplify a signal that rides on top of some large voltage level. If the common-mode voltage is not rejected, it appears as an error at the amplifier output.
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How to Derive the Differential Amplifier Transfer Function
Thursday, May 7th, 2009Summary:
The transfer function of the differential amplifier, also known as difference amplifier, can be found in articles, websites, formula tables, but where is it coming from? Why is the differential amplifier transfer function as in the following mathematical relation? …
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Solving the Differential Amplifier – Part 3
Sunday, May 3rd, 2009Summary:
Designing the differential amplifier by inspection is part of the art in the analog design. Inspecting the circuit and knowing how it works, it really gives you a feeling on what the values of the resistors should be.
Looking back at the example I took in Solving the Differential Amplifier – Part 1 and 2, we need to have an output signal of -1.25V to +2.365V with an input signal of -0.5V to 5.5V. In those two articles I used the differential amplifier transfer function and I applied math to find the resistors.
This time I am going to demonstrate how this circuit can be solved by simple reasoning and knowing how it works. Some calculations are also necessary. Cannot get rid of math totally.
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