Oscilloscopes
By: Kr. Rajeev Ranjan May 8, 2010
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Introduction: Theory of Oscilloscope
What is an oscilloscope?
Cathode Ray Oscilloscope -first oscilloscope May 8, 2010
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Introduction •A graph-displaying device of electrical signal •X axis: Time •Y axis: Voltage •Z axis: Intensity or brightness
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Information Given by Oscilloscope •Time and voltage •Frequency and phase •DC and AC components •Spectral analysis •Rise and fall time •Mathematical analysis Any Thing Else??? Guess ??? May 8, 2010
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What can you do with Oscilloscope? • Designing and repairing electronic equipment • With the proper transducer (Ex: microphone) – Electrical signal in response to physical stimuli, such as sound, mechanical stress, light, or heat. – Engine vibrations – Brain waves
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Control panel of an Oscilloscope • Vertical Section • Horizontal Section • Trigger Section
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Basic Setting: • Vertical system – attenuation or amplification of signal (volts/div)
• Horizontal system – The Time base (sec/div)
• Trigger system – To stabilize a repeating signal and to trigger on a single event
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In Digital Circuit • Measuring – Logic level – Timing – Logic strength – Rise and fall time – Frequency – Signal integrity May 8, 2010
• Waveform distortion • Noise level
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In Digital Circuit • Diagnosing – Timing fault – Proper fan-in and fan-out – Proper pull-up and/or termination – Collision – Signal integrity • Reflection • Noise, crosstalk and ground bounce
– Open, short or stuck at 0 or 1
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Type of Oscilloscope Analog and digital oscilloscope
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Analog Oscilloscope • Real-time display of signals • Block diagram – Sweep generator and vertical amplifier – Earthquake recorder
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Digital Oscilloscope • Capture and view events – Digital storage oscilloscope (DSO)
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Digital Oscilloscope Contd…
Sampling
Interpolation
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Advantages of Digital Oscilloscope May 8, 2010
Trend towards digital. Easy to use. One-shot measurement Recoding Triggering Data reuse Connectivity 14
Probes used in CRO/DSO Components
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Probes Properties •High quality connector •High impedance (10M) •50 for high frequency measurement
Types •Active Probe •Passive Probe
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Passive Probe • 10 attenuation – Good for low circuit loading – Suitable to high frequency signal – Difficult to measure less than 10mV signals • 1 attenuation – Good for small signals – Introducing more interference May 8, 2010
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Active Probe • Signal conditioning ⇒ oscilloscope • Require power source • Good for high speed digital signals over 100MHz clock frequency
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Summary Oscilloscope: A graphical device showing voltage w.r.t time. Types •Analog or Cathode Ray Oscilloscope •Digital or Digital Storage Oscilloscope
Probes used in CRO/DSO should be High quality connector and its impedance should be properly matched. Active Probe and Passive Probe are there as per the requirements
Applications
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Design and Debug Education and Training Manufacturing Test and Quality Control 19 Service and Repair
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