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Harmonics and Interharmonics 47
i D (t)
T
90%
T D
10%
t
t r
(a)
f 1
−20 dB / Decade
f 2
−40 dB / Decade
f 0 2f 0 3f 0 4f 0 5f 0 6f 0 7f 0 8f 0 9f 0 10f 11f 0
0
f
(b)
Figure 4.4 Trapezoidal waveform. (a) Current waveform that may
be produced by a DC/DC converter or other electronic system.
(b) Spectrum.
rate of 40 dB/decade. It can be shown that the two corner frequencies f 1
and f are found by [4.4], [4.5]:
2
1
f 5
1
pT d
1
f 5
2
pt r
Root-mean square
Root-mean square is a measure of the heating value of a periodic waveform
when this periodic waveform drives a resistive load. Mathematically, the
