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Pulse Width
The pulse width (tp), or pulse duration, is defined by a pulse level
equal to 50% of the peak value.
For the ideal pulse of Fig. 24.1, the pulse width is the same at any level,
whereas tp for the waveform of Fig. 24.2 is a very specific value.
Base-Line Voltage
The base-line voltage (Vb) is the voltage level from which the pulse is
initiated.
The waveforms of Figs. 24.1 and 24.2 both have a 0-V base-line voltage.
In Fig. 24.3(a) the base-line voltage is 1 V, whereas in Fig. 24.3(b)
the base-line voltage is �4 V.
5 V
V b = 1 V
v
Amplitude = 4 V
0 t
(a)
–10 V
FIG. 24.3
Defining the base-line voltage.
Positive-Going and Negative-Going Pulses
A positive-going pulse increases positively from the base-line voltage,
whereas a negative-going pulse increases in the negative direction
from the base-line voltage.
The waveform of Fig. 24.3(a) is a positive-going pulse, whereas the
waveform of Fig. 24.3(b) is a negative-going pulse.
Even though the base-line voltage of Fig. 24.4 is negative, the waveform
is positive-going (with an amplitude of 10 V) since the voltage
increased in the positive direction from the base-line voltage.
– 1 V
9 V
v
0 t
V b
t p
FIG. 24.4
Positive-going pulse.
Amplitude = 10 V
v
IDEAL VERSUS ACTUAL ⏐⏐⏐ 1095
0 t
V b = – 4 V
(b)
Amplitude = – 6 V