Frequency Content of Digital Signals

Summary

This chapter focuses on Fourier series and frequency content of digital signals. There are two forms of the Fourier series: trigonometric and exponential. The complex exponential form is more useful and more easily computed than the trigonometric form. Clock waveforms can be represented as periodic trains of trapezoid‐shaped pulses. Each pulse is described by the key parameters: period, amplitude, rise time, fall time, and the on‐time or pulse width. The chapter investigates the effect of these pulse parameters on the spectrum of the clock waveform. To obtain the complex‐exponential Fourier series of this waveform, the chapter uses the computational techniques. It explains effect of the signal amplitude, fundamental frequency, and duty cycle on the frequency content of trapezoidal signals. Reducing the signal amplitude reduces the frequency content over the entire frequency range.