# Reduce T-Network Feedback Resistance

• JasonHathaway
In summary, The Thevenin approach is a good method to reduce the feedback resistance in a T-Network. It is unlikely that the resistance can be simplified further without plugging in actual values. Another option is to use the star-triangle transformation, which can eliminate two resistors that do not affect the closed-loop gain.

## Homework Statement

Reduce the feedback resistance for the following T-Network

## Homework Equations

Basic circuit analysis (Thevenin maybe?)

## The Attempt at a Solution

My first though was to use Thevenin, and actually I've found some book used that method:

The Thevenin approach looks fine. Did you have some question about it?

Thank you for your quick respond. My question is whether this approach OK or not. And if the feedback resistance can be reduced more.

JasonHathaway said:
Thank you for your quick respond. My question is whether this approach OK or not. And if the feedback resistance can be reduced more.
The approach is good, and I doubt that the resistance can be simplified further (other than rearranging it algebraically) without plugging in actual values to reduce it to a number.

JasonHathaway said:
Thank you for your quick respond. My question is whether this approach OK or not. And if the feedback resistance can be reduced more.
Typically it is a good idea to get it in the form of

G=NUM/DEN.

in other words, simplify to get rid of R2*R3/R4 in the Numerator

As an alternative, you can apply the star-triangle transformation.
After applying this transformation there will be two resistors which do not influence the closed-loop gain (and can be neglected).

## 1. What is a T-network feedback resistance?

A T-network feedback resistance is a type of electrical circuit that is commonly used in amplifiers to reduce the amount of feedback that occurs between the input and output signals. It consists of three resistors arranged in a "T" shape, with one resistor connected between the input and ground, and the other two resistors connected in series between the output and ground.

## 2. How does a T-network feedback resistance work?

A T-network feedback resistance works by creating a voltage divider between the input and output signals. This means that a portion of the output signal is fed back to the input, but it is attenuated by the resistors in the network. This reduces the amount of feedback that occurs, which can help to improve the stability and performance of the amplifier.

## 3. Why is it important to reduce T-network feedback resistance?

Reducing T-network feedback resistance is important because it can help to prevent unwanted oscillations or instability in an amplifier. If there is too much feedback, it can cause the amplifier to become unstable and produce distorted or noisy output signals. By reducing the amount of feedback, the amplifier can operate more reliably and produce cleaner output signals.

## 4. How do you calculate the feedback resistance in a T-network?

The feedback resistance in a T-network can be calculated using the formula: Rfb = R1 + (R2 * R3) / (R2 + R3). This formula takes into account the values of the resistors in the network and determines the overall feedback resistance. It is important to choose appropriate resistor values to achieve the desired amount of feedback reduction.

## 5. Are there any drawbacks to using a T-network feedback resistance?

While T-network feedback resistance can be beneficial in reducing feedback, it can also introduce some drawbacks. One potential issue is that it can decrease the gain of the amplifier, as some of the output signal is being attenuated. Additionally, T-networks can introduce unwanted phase shifts in the circuit, which can affect the frequency response of the amplifier. These factors should be carefully considered when deciding whether to use a T-network feedback resistance in an amplifier circuit.