Design of differential amplifier

[kasse]

Homework Statement

http://i36.tinypic.com/hugkyb.jpg

Homework Equations

According to my book, if R₃ = R₂ and R₄ = R₁, I can use the following formula:

V_o = (R₂/R₁)(V₂ - V₁).

The Attempt at a Solution

We want R₂/R₁ to equal 5. This means that R₃ and R₂ must be 5*3,3 = 16.5 k(ohms).

However, I don't know what to do with the inner resistance of V₂ and V_o. Any suggestions?

 

[dlgoff]

For an ideal op-amp, the input current is zero.

 

[piercas]

The design of a differential amplifier is a fundamental aspect of electronic circuit design, and it plays a crucial role in many applications. The circuit diagram provided in the homework statement shows a basic differential amplifier configuration with two input signals, V1 and V2, and an output signal, Vo. The goal of this circuit is to amplify the difference between the two input signals while rejecting any common-mode signals that may be present.

To design this circuit, we can use the formula provided in the problem, Vo = (R2/R1)(V2 - V1). This formula assumes that R3 = R2 and R4 = R1, which results in a gain of 5. This means that the output voltage will be 5 times larger than the difference between the two input signals.

To achieve this gain, we can choose R1 and R2 to be 16.5 k(ohms), as suggested in the attempt at a solution. However, it is important to also consider the inner resistance of V2 and Vo. The inner resistance of V2 can be taken into account by adding it in series with R2, while the inner resistance of Vo can be taken into account by adding it in parallel with R1.

It is also worth noting that the values of R3 and R4 can be chosen independently, as long as their ratio is equal to the ratio of R2 and R1. This means that we have some flexibility in choosing the values of R3 and R4, as long as their ratio is maintained.

In summary, the design of a differential amplifier involves choosing appropriate values for the resistors in order to achieve the desired gain and to take into account the inner resistance of the input and output signals. It is important to carefully consider these factors in order to ensure the proper functioning of the circuit.