The Waveform & Characteristics Presentation Presented By: Sufian Mehmood Soomro Department: (BS) Computer Science Course Title: Digital Logic & Design Shah Abdul Latif University Ghotki Campus

1. Sufian Mehmood
Soomro
(BS) Computer Science
3rd Semester
Digital Logic Design
Shah Abdul Latif University Ghotki Campus

2. Digital Waveform
Digital Waveform Characteristics
01
02
CONTENT

3. 01
ONE
Digital Waveform
Digital Waveform

4. Digital Waveform
ØConsist of voltage levels that change back and forth between the
HIGH and LOW states.
ØPositive-going pulse – generated when the voltage goes from LOW
level to HIGH level and back to LOW level
ØNegative-going pulse – generated when the voltage goes from
HIGH level to LOW level and back to HIGH level
A Digital Wavefrom
is made-up of a series of pulses

5. Digital Waveform
v Diagram: Positive (+ve) & Negative (-ve) Going Pulse
Rising/ Leading
Edge
Low
Falling / Tralling
Edge
t0 t1
High High
Low
Falling /Leading
Edge
Rising/ Tralling
Edge
t0 t1
Positive (+ve) Going Pulse Negative (-ve) Going Pulse

6. Digital Waveform
ØLeading edge (occurs first at t = 0)
ØTrailing edge (occurs last at t = 1)
ØPositive-going pulse: Leading edge is a rising edge and trailing
edge is falling edge
ØNegative-going pulse: Leading edged is falling edge and trailing
edge is rising edge
v Pulse Characteristics:

7. Digital Waveform
Amplitude
Baseline
Rise time (tr) Fall time (tf)
Pulse width (tw)
v Diagram: Non-Ideal Pulse

8. Digital Waveform
Ø Rise time (tr) is the time required for a pulse to go from its LOW to
HIGH level (measured 10% to 90% of the pulse amplitude).
ØFall time (tf) is the time required for the transition from the HIGH to
LOW level (measured 90% to 10% of the pulse amplitude).
ØPulse amplitude height of the pulse from baseline.
ØPulse width (tw) duration of the pulse (defined as the time interval
between the 50% points on the rising and falling edges).
v Pulse Parameters:

9. 02
ONE
Digital Waveform
Characteristics
Digital Waveform Characteristics

10. Digital Waveform Characteristics
Ø Most waveforms are composed of a series of pulses (pulse trains)
Ø Pulses can be either –
Ø periodic – repeats itself at a fixed interval called a period
(T)).
Ø The frequency, f, is the rate at which it repeats itself and is
measured in Hertz (H)
Ø non-periodic – does not repeat itself at fixed intervals and may be
composed of pulses of different pulse widths.
v Waveform Characteristics

11. Digital Waveform Characteristics
Ø Frequency of a pulse, f, is the reciprocal of its period, T
Ø f = 1/T
Ø T = 1/f
Ø Duty cycle – the ratio of the pulse width (tw) to the period (T),
expressed as a percentage
Ø Duty Cycle = (tw/T)x100%
v Waveform Characteristics

12. Thanks!