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222
Baseband Pulse and Digital Signaling Chap. 3
Analog input
signal
Triangle
function
generator
+
+
+
Comparator
–
V r = reference level
Monostable
multivibrator
PWM
output
PPM
output
Analog
input
signal
t
Triangle
t
V r
Analog
plus
triangle
t
PWM
t
PPM
Figure 3–45
Technique for generating naturally sampled PTM signals.
t
be a truncated ramp. After the PWM signal goes low, the amplitude of the truncated ramp signal
will be equal to the corresponding PAM sample value. At clocking time, the output of the
integrator is gated to a PAM output line (slightly before the integrator is reset to zero), using a
sample-and-hold circuit. The PAM signal is then converted to the analog signal by low-pass