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Unformatted text preview: V p V pp T Class notes for the week of October 1 st Periodic signals: DC circuits are kind of boring, after all they don’t do anything. On the other hand, the kinds of signals that we are most interested in (music, video, streams of text) are very complex and difficult to analyze. A good compromise is to evaluate our circuits with repetitive time varying signals. These require that the circuit under test do something , but at the same time it is not too hard to figure out what that something is! There are a few favorite periodic signals that are widely used for test and also in circuits. • Square wave: The output alternates between one voltage level and another. Ideally, the transition time between these two levels is zero. That can never happen, but these signals find many applications to control the timing of digital circuits. A true square wave has the output ‘high’ and ‘low’ (as viewed on an oscilloscope) for equal time intervals. The duty cycle is the ratio of the high time to the low time and is 50% for the square wave. • Rectangular wave: This is like a square wave, except that the high time and low time are not necessarily the same. The duty cycle here may not be 50%. • Triangle wave: The output linearly increases from one voltage to another. When it reaches the second voltage it reverses course and linearly returns to the first voltage. A true triangle wave spends the same amount of time increasing as it voltage....
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This note was uploaded on 09/26/2008 for the course ESE 123 taught by Professor Westerfield during the Fall '07 term at SUNY Stony Brook.
- Fall '07