# 18-03-2024: Electronics 11#

Date: Monday, March 18 2024

Location: Pi

Time: 10:45 - 12:30

Question of the day

How do we find requirements for the controller?

## Knowledge Test#

Press the button(s) below to test your knowledge and understanding of the topics covered this lecture.

## Modeling of negative feedback circuits#

Two-step design of negative-feedback amplifiers

The design of negative-feedback amplifiers can be performed in two steps:

The design of the

*ideal gain*of the amplifier. This comprises the design of the structure of the amplifier with feedback networks and nullors as ideal controllers.The design of the controller(s) (also

*error amplifiers*)

This two-step design method requires that butgets for performance limitations of the amplifier are split into error budgets for the feedback networks and error budgets for the controller.

**Presentation**

The presentation Two-step design of negative feedback amplifiers shows that a feedback model that supports the two-step design of negative feedback amplifiers will tell us in which way and to what extent performance limitations of the amplifier are affected by performance limitations of the controller(s).

**Presentation in parts**

Two-step design of negative feedback amplifiers (parts)

**Video**

Two-step design of negative feedback amplifiers

**Study**

Chapter 10.1

Feedback model of Black

In 1927, Black built the first negative feedback amplifier. The feedback model of Black is commonly used to evaluate the dynamic performance of negative feedback systems. However, Black's feedback model is not optimally suited for the analysis of dynamic behavior of electronic feedback amplifiers and providing meaningful design information from such analysis.

**Presentation**

The presentation Feedback model of Black introduces the feedback model of Black and shows its limitations for the analysis of electronic feedback circuits.

**Presentation in parts**

Feedback model of Black (parts)

**Video**

**Study**

Chapter 10.2

Asymptotic-gain feedback model

The asymptotic-gain feedback model provides a solid base for relating controller imperfections such as:

Static (DC) gain limitation

Bandwidth limitation

Weak nonlinearity (differential gain)

to important performance limitations of the amplifier:

Gain inaccuracy

Frequency response

Differential gain

**Presentation**

The presentation Asymptotic-gain model introduces the asymptotic-gain feedback model.

**Video**

Asymptotic-gain feedback model

**Study**

Chapter 10.3.1, 10.3.2

Selection of the loop gain reference variable

The analysis of feedback circuits with the asymptotic-gain feedback model gives the same result as network analysis techniques. However, if the loop gain reference is selected in a proper way, the asymptotic-gain model provides much more design information and it facilitates two-step design of negative feedback circuits.

**Presentation**

The presentation Selection of the loop gain reference illustrates the way in wich the loop gain reference should be selected such that the model provides meaningful design information.

**Presentation in parts**

Selection of the loop gain reference (parts)

**Videos**

**Downloads**

SLiCAP_python source files Chapter 10

**Study**

Chapter 10.3.3, 10.3.4

## Downloads#

## Homework#

Evaluate the frequency characteristics of the asymptotic-gain, the loop gain and the servo function for the transmitter equipped with the TLV4111, designed to deliver 100mA peak into the transmit coil. Use SLiCAP to plot the frequency characteristics.

Evaluate the frequency characteristics of the asymptotic-gain, the loop gain and the servo function for the receiver equipped with the OPA209, designed with a transmitter that delivers 100mA peak into the transmit coil. Use SLiCAP to plot the frequency characteristics.