To start off, I simulated a base square wave with a sine wave harmonic at twice the base frequency as in Figure 1. I put a square wave source in series with a sine wave source at twice the square
wave's frequency and viewed the result with a virtual dual
trace oscilloscope. The base frequency is in black and the
sine wave is in red.
Figure 2 shows the simulated circuit used to create
the wave form in Figure 1. A harmonic switch was added
so that the enhancement could be switched off and the
This article uses simulation to explore
harmonics, which are whole number
multiples of a base frequency. Harmonics
form a base line for testing, comparing, and
explaining various circuits. The term can
also refer to the ratio of the frequency of
such a signal or wave to the frequency of the
reference signal or wave.
UNDERSTANDING
HARMONICS
USING
SIMULATION
By Richard Agard
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FIGURE 1. Enhanced square wave with second
harmonic interference.
FIGURE 2.
Simulation circuit
used in Figure 1.
October 2015 31
