Presentations
EE4109 Lecture 2 agenda
Presentation
The presentation “EE4109 Lecture 2 Agenda ” shows the agenda for lecture 2.
Poster
Wrap-up: “Application of Negative Feedback”
Negative feedback can be regarded as a powerful error reduction technique. The transfer of a negative feedback amplifier can ideally be fixed with the aid of accurate (passive) components. Active components are only used in a controller or error amplifier that nullifies the error with respect to this ideal transfer.
By doing so, the inaccuracy and the differentail gain error of the feedback amplifier can be much smaller than that of its controller, while the bandwidth of the feedback amplifier can be much larger than that of its controler.
The load drive capability and the equivalent input noise sources of a negative feedback amplifier, at best equal those of its controller.
The above results in a clear design sequence for negative feedback amplifiers in which the various performance aspects can be designed independently (orthogonal design).
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Relevant presentations from EE3C11
Below, the relevant presentations from EE3C11 including links to video recordings.
Amplifiers: functions and requirements (wrap up)
A short wrap up of the amplification function and performance limitations in amplifiers.
Presentation
The presentation “Amplifiers, functions and requirements (wrap up)” briefly summarizes the basic function of amplification, characteristic properties of amplifiers and performance aspects, environmental conditions and cost factors.
Amplifiers: basic function design approach
The design approach for basic functions is based upon the:
Presentation
The presentation “Amplification” briefly summarizes the approach of the design of basic functions, as advocated in structured electronic design.
Amplifiers: application of negative feedback
Negative (corrective) feedback can be regarded as a powerful error-reduction technique. It trades power gain for quality improvement and facilitates orthogonal design of the various performance aspects.
Presentation
The presentation “Amplifiers: application of negative feedback”shows that accurate, low-noise and power-efficient amplifiers can be realized through application of negative feedback.
Videos
Study
Chapter 7.1
Feedback amplifiers: orthogonal design sequence
In electronic information processing systems, amplification is one of the most important basic functions. Since the basic amplification mechanism, as it is found in biased ‘active’ devices, suffers from many imperfections, negative feedback is often exploited as powerful error reduction technique.
The application of negative feedback, together with proper sequencing of the design of various performance aspects makes it possible to prevent or minimize design iterations and have an early awareness of possible show-stoppers.
Presentation
The presentation “Structured design of negative feedback amplifiers” gives the outline of the design sequence of high-performance negative feedback amplifiers.
Video
Amplifiers: design procedure feedback configurations
The design of negative amplifier configurations follows a strict procedure based on sensing and comparison techniques.
Presentation
The presentation “Feedback amplifiers: design procedure” illustrates the procedure for the design of a negative-feedback amplifier that accurately relates the desired electrical quantity at the load of the amplifier to that of the signal source.
Study
Chapter 7.2
Amplifiers: design of single-loop feedback configurations
Sensing of the load quantity and nullification of the difference between the feedback quantity with the source quantity form the basis of the design procedure of negative feedback amplifiers.
Presentation
The presentation “Design of Single-loop Negative Feedback Amplifier Configurations” illustrates the application of the design procedure for negative feedback amplifiers to the design of single-loop negative feedback amplifiers:
It illustrates a number conflicts between design aspects for passive feedback amplifiers:
Video
Amplifiers design of single-loop feedback configurations (11:41)
Study
Chapter 7.2
Feedback amplifiers: ideal gain
The conceptual design or functional design of negative feedback amplifiers comprises the design of the feedback networks and their interconnection with the source, the load and nullors.
Presentation
The presentation “Negative Feedback Amplifier Configurations: Ideal Gain and Controller” gives a definition of the gain of negative feedback amplifiers that have ideal controllers (nullors). The implications of controller imperfections will be discussed at a later stage.
Video
Negative Feedback Amplifier Configurations Ideal Gain and Controller (3:35)
Study
Chapter 7.3
Amplifiers: multiple-loop feedback configurations
Each transmission-1 two-port parameter of an amplifier can be given an accurate value with the aid of a feedback network around a high-gain controller.
Presentation
The presentation “Design of Multi-loop Negative Feedback Amplifier Configurations” briefly discusses the design of multiple-loop negative feedback amplifiers.
Video
Amplifiers multiple-loop feedback configurations (2:58)
Study
Chapter 7.3, 7.4.1
Noise performance of feedback amplifiers
In general, insertion of impedances in series and/or in parallel with the signal path should be avoided. They increase:
Presentation
The presentation “Influence of Feedback Networks on Noise Performance of Negative Feedback Amplifiers” shows that detrimental effects caused by impedances in the feedback networks can be kept low.
Video
Noise behavior of negative feedback amplifiers (19:42)
Study
Chapter 7.4, 7.5
Discussion of homework: Lecture2SLiCAP.zip.
Guidance with homework
Chapter 7
The theory presented in this lecture will be applied in the design of the active antenna. Please use SLiCAP as documentation tool.
In which way does the length of the antenna affect the amplifier’s noise requirements?
After having completed the exercises of the first lecture, we may conclude that the amplifier can be realized as a voltage amplifier with 50 \(\Omega\) output impedance, or as an integrating transimpedance amplifier with 50 \(\Omega\) output impedance. We have also seen that the antenna should not be longer than a quarter of the wavelength of the maximum frequency, because above this frequency the sensitivity will drop.
Design feedback configurations for the active antenna. You may use nullors as controllers and transformers and passive network elements as feedback elements.
Evaluate the ideal values of the transmission-1 matrix parameters of the configurations from the previous exercise and verify the obtained results with SLiCAP.
Consider the effect of the passive elements in your configurations on the noise performance.
Consider the influence of the passive elements in your configurations on the power dissipation and the voltage and current-drive capability of the controller.
The input of the amplifier for the active antenna should be protected against overdrive and ESD. Consider this will be done with ESD protection diodes in parallel with the input. Those diodes suffer from:
At this stage of the design, which of the your configurations shows the lowest impact of the input ESD protections on the signal processing quality? Please motivate your answer.
Make a comparison table for the design configurations that shows a qualitative comparison of the most important performance aspects and cost factors at this stage of the design.
