## TRANSITION FROM ECE 109 TO ECE 207

### ALAN FELZER, CAL POLY POMONA

The overall objective of ECE 109 was to develop methods for analyzing linear resistor circuits. The class began with a detailed study of Kirchhoff's Laws and Ohm's Law since they form the foundation for all subsequent results. We then analyzed series and parallel resistor circuits since they are not only the easiest to analyze but also because they are so common. We developed voltage division for series circuit analysis and current division for parallel circuit analysis.

We then developed node equations for the analysis of more general circuits like the following that have no circuit elements that are in series or in parallel. Node equations are not always the most efficient way to analyze such circuits but they usually are and they always work. And once we've gotten the node voltages, it's very simple to then calculate all the rest of the voltages and currents in the circuit.

We then used node analysis to demonstrate some of the basic properties of general linear resistor circuits including the following

1. Arbitrary circuits of resistors are equivalent to single resistors
2. All voltages and currents in circuits with one source are proportional to the source
3. Linear circuits with more than one source can be analyzed with superposition
4. Circuits with resistors and sources have Thevenin as well as Norton Equivalents

These results are important not only because they greatly simplify analysis but also because they are useful in design as you will see.

The overall goal of ECE 207 is to extend the methods we developed in ECE 109 for the analysis of linear resistor circuits to circuits containing not only resistors and independent sources (power supplies and batteries) but also controlled sources, capacitors and inductors.

The first new material in ECE 207 is an introduction to controlled sourcesand the analysis of resistor circuits containing them. What we find is that such circuits can be analyzed in basically the same way as purely resistor circuits can and that they have the same basic properties except for one Đ circuits containing controlled sources can amplify signals. We then apply these results to the analysis of resistor op amp circuits.

Now as we've said, controlled sources are great for amplifying signals butto build circuits that can separate one signal from another Đ like one radio station from another Đ and to build circuits that have memory we need to introduce capacitors and inductors. What we find is that these circuits also obey Kirchhoff's Laws and so can be analyzed with node equations. But now we must solve differential equations to analyze them. Our objective in ECE 207 is to show how to analyze simple circuits containing capacitors and inductors as well as find the basic properties of these circuits.

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