Investigation of the Noise Figure of Basic Amplifiers

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Szombathy Csaba Zoltán
Department of Broadband Infocommunications and Electromagnetic Theory

The theme of this thesis is noise, more precisely the noise figure and the methods of measuring it. The idea came to me reading an article about the noise figure of a transimpedance amplifier. In order disclose the depths of that in pracitce, it is essential to understand the nature of noise and how to handle it as an engineer.

In the first few chapters mathematical models of noise will be presented along with some usually relevant noise types in electrical circuits. But designing proper circuits is rather time consuming using solely these models therefore a more practical quantity is introduced called the noise figure. This parameter is often used to measure noise or signal-to noise ratio within electrical circuits, thus it is presented more thoroughly. The next few chapters will include information on how to measure it and how to avoid common errors before even starting.

Having summerized the basics of noise, it is essential to introduce the so called transimpedance amplifier which is going to be measured later on. With the requiered knowledge acquiered, a piece of printed circuit consisting of said amplifier will be built in order to investigate it. The last main chapters are about the measuremet process, the precautions and the the detailed presentation of the methods used in order to improve the results. Last, a comparison of the theoritical and the measured values will be shown, finally evaluating the process and the thesis itself.


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