Oscilloscope Tricks - Top of the p(acq)
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This document provides an overview of oscilloscope triggers and other components. It discusses how the trigger circuit works to determine when the oscilloscope acquires data from the analog-to-digital converter. The trigger looks for a specific edge or pattern in the signal and uses that to tell the oscilloscope when to start sampling and storing data. There are different trigger modes like edge, pulse width, and delay that are implemented using comparators and timing circuits. Proper use of the trigger is important for acquiring stable waveforms and avoiding jitter. The document also briefly outlines other oscilloscope subsystems like the attenuator, acquisition memory, and display and provides additional learning resources.
Oscilloscope Tricks - Top of the p(acq)
- 1. Oscilloscope Triggers And other things you never knew 1 A/D Converter Acquisition Memory Trigger Circuit Memory Controller Time base Vertical Edge Logic Analog Sample Rate 1ns 1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns Digital Resolution = Sample Rate 1 1Ga/s 1 = 1ns= 1 2 3 4 5 6 7 8 9 10 11 12 13 1 2 3 4 5 6 7 8 9 10 11 12 13 Sample Rate 1ns 1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns Digital Resolution = Sample Rate 1 1Ga/s 1 = 1ns= 1 2 3 4 5 6 7 8 9 10 11 12 13 If your event occurs exactly when a sample does, buy some lotto tickets.
- 2. Top of the P(acq) 2 James Lewis james@baldengineer.com email | twitter | www
- 3. 3 Have you ever used an oscilloscope?
- 4. Inside Oscilloscope 4 Have you ever looked inside one?
- 5. Scope Screen 5 Graticules are overrated Trigger Point Sampling Trigger Type
- 6. Scope Block Diagram Attenuator A/D Converter Acquisition Memory CPU Display Trigger Circuit Memory Controller Time base Vertical Amplifier Edge Logic Analog 6 All digital scopes contain these blocks, sometimes arranged a little different.
- 7. 7 Front-End Amplifier Attenuator A/D Converter Acquisition Memory CPU Display Trigger Circuit Memory Controller Time base Vertic Edge Logic Analog 7
- 8. Whered my signal go? 8
- 10. -3db Magic 10 0db -3db fBW Attenuation Frequency Analog Digital Attenuator Vertical Amplifier Modern digital oscilloscopes dont roll-off like traditional analog did. Their Bandwidth IS their bandwidth.
- 11. Avoid Overdrive 11 ? 11 Off-screen signals overdrive the amplifier, creating distortion
- 13. Real-Fme Sampling 13 Digital Resolution = Sample Rate 1 1Ga/s 1 = 1ns= Sample Rate 1ns 1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns 1 2 3 4 5 6 7 8 9 10 11 12 13 1 2 3 4 5 6 7 8 9 10 11 12 13
- 14. DSP Path 14 Memory Controller DSP Correction Transfer to PC Sin X / X DSP Boost DSP Correction Linear Interpolation Measure Math Cursors (oh and Display) Acquisition Memory CPU Correction can include calibration factors for a specific scope channel.
- 16. Display 16 Sample Rate 1ns 1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns 1 2 3 4 5 6 7 8 9 10 11 12 13 1 2 3 4 5 6 7 8 9 10 11 12 13 1 2 3 4 5 6 7 8 9 10 11 12 13 Interpolation isnt just for waveform display
- 18. Measure 18 90% 10% When making measurements, most scopes default to 10-90 points. Interpolation method matters. Ideal Thresholds As Sampled Interpolated Thresholds
- 19. Make use of Zoom 19
- 21. What does Trigger Do? A/D Converter Acquisition Memory Trigger Circuit Memory Controller Time base Vertical Edge Logic Analog Sample Rate 1ns 1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns Digital Resolution = Sample Rate 1 1Ga/s 1 = 1ns= 1 2 3 4 5 6 7 8 9 10 11 12 13 1 2 3 4 5 6 7 8 9 10 11 12 13 Sample Rate 1ns 1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns Digital Resolution = Sample Rate 1 1Ga/s 1 = 1ns= 1 2 3 4 5 6 7 8 9 10 11 12 13 21 Analog events in the digitized waveform
- 22. Do you even Edge, Bro? 22 AA B Positive Edge AA B Negative Edge A B OUT A B OUT Flip-Flop
- 23. Do you even Edge, Bro? 23 Ref Comparator Edge Detector Trigger-Output Bu鍖er Signal from Pre-Amp Edge Trigger Ref Comparator Edge Detector Trigger-Output Bu鍖er Signal from Pre-Amp Edge Trigger
- 24. Moar Modes 24 Ref Comparator Edge Detector Trigger! Signal Under Test Counter Control Logic Pulse Width SlopeDelay Runt Ref Comparator Edge Detector Signal Under Test Multiple Modes with the Same Hardware: Couple of Comparators and a timer
- 25. Triggers arent perfect A/D Converter Acquisition Memory Trigger Circuit Memory Controller Time base Vertical Edge Logic Analog Sample Rate 1ns 1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns Digital Resolution = Sample Rate 1 1Ga/s 1 = 1ns= 1 2 3 4 5 6 7 8 9 10 11 12 13 1 2 3 4 5 6 7 8 9 10 11 12 13 Sample Rate 1ns 1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns1ns Digital Resolution = Sample Rate 1 1Ga/s 1 = 1ns= 1 2 3 4 5 6 7 8 9 10 11 12 13 25 If your event occurs exactly when a sample does, buy some lotto tickets.
- 26. Trigger JiOer 26 Trigger jitter is a cumulation of error It doesnt specify any one good or bad aspect
- 27. Digital Trigger 27 R&S has a unique digital trigger system
- 28. InteresFng Content https://www.youtube.com/user/KeysightOscilloscope Tons of Scope Videos http://www.scope-of-the-art.com R&S Scope Dedicated Site http://teledynelecroy.com/events/?capid=107&mid=555 Free Seminars (Plus other good Content) 28
- 29. 29 Download 際際滷s At: baldengineer.com/hddg22 James Lewis james@baldengineer.com email | twitter | www