1. 1 Oscilloscope Capabilities and Demonstration April 2004 Trace Hitt Account Manager Tektronix, Inc.

2. 2 Oscilloscopes – Why Do We Need Them? To Verify:  Measure and Control Known Operation  Calibrate  Characterize  Analyze To Troubleshoot:  Find Unknown Operation  Search for a Problem or Defect  Test for Limits  Observe New Phenomena Through Research

3. 3 How Can They Give Us Incorrect Information? By:  Not showing waveshape information that really exists - when detail of interest occurs during holdoff, between samples, or is too fast for the writing speed of the oscilloscope to display  Showing waveshape information that does not exist - such as aliasing, aberrations or distortion

4. 4 Evaluate Your Needs The key to any good oscilloscope system is its ability to accurately reproduce your waveform.

5. 5 Agenda Bandwidth and Rise Time Acquisition and Display Modes Sampling and Digitizing Aliasing, Sample Rate and Interpolation Waveform Capture Rate Triggering Modes DPO

6. 6 Select the Right Bandwidth Bandwidth is sine wave frequency where amplitude is down 30% or 3dB. Bandwidth x Risetime = 0.35* i.e. 100 MHz Bandwidth will have 3.5 nsec Rise Time When system bandwidth increases, system rise time decreases. 0 dB 6 div at 50 kHz - 3 dB 4.2 div at 100 MHz * This constant is based on a one pole model. For higher bandwidth instruments, this constant can range as high as 0.45.

7. 7 Rise Time of Step Waveform Rise Time of Waveform, t r 100% 90% 10% 0%

8. 8 Bandwidth and Amplitude Accuracy  At the 3dB bandwidth frequency, the vertical amplitude error will be approximately 30%.  Vertical amplitude error specification is typically 3% maximum for the oscilloscope.  When you depend on the specified maximum vertical amplitude error, divide the specified bandwidth by 3 to 5 as a rule of thumb, unless otherwise stated. 70.7 (- 3 dB) 0.10.20.30.40.50.60.80.91.00.7 100% 97.5 95 92.5 90 87.5 85 82.5 80 77.5 75 72.5 } 3% t ris e 0.35* BW = Sine Wave Frequency Sine Wave Amplitude

9. 9 Measurement System Bandwidth Requirements (t rise (scope + probe) ) 2 + (t rise (source) ) 2 5 - 20 ns 17.5 - 70 MHz 2 ns175 MHz 500 ps700 MHz 200 ps1.75 GHz 58 – 233 MHz 87.5 - 350 MHz 580 MHz875 MHz 2.33 GHz3.5 GHz 5.8 GHz8.75 GHz Analog Video, Electro- Mechanical TTL, Digital TV CMOS HDTV, LV CMOS Device Under Test Typical Signal Rise Times Measurement Bandwidth for  3% Rolloff Error Measurement Bandwidth For  1.5% Rolloff Error Calculated Signal Bandwidth = 0.35* t rise t rise (displayed) =

10. 10 Choose the Right Voltage Probe For the Application 15 MHz23 ns100 pF 1 M  100 MHz - 500 MHz 3.5 ns - 700 ps 13 pF - 8 pF 10 M  3 GHz - 9 GHz 120 ps - 40 ps 1 pF - 0.15 pF 500  500 MHz - 6 GHz 700 ps - 80 ps 2 pF - 0.4 pF 1 M  - 20 k  1X Passive Probe 10X Passive Probe Z0 Passive Probe Active Probe TypeBandwidthInput CInput RRise Time

11. 11 Vertical Position  Moves the Volts/Div Reference Point On Screen  Is Expressed In Divisions Ref at +4 Divs Ref at -4 Divs Possible Display Screens

12. 12 Vertical Offset  Changes the Volts/Div Reference From 0 to Some Other Voltage  Is Expressed In Volts +5 Volts 100 mV/Div

13. 13 What About Horizontal Time Resolution?  Two criteria are affected when improving resolution (decreasing time) between samples for a given time window. You need...  More Sample Rate (Speed) for less time between acquisition samples.  More record length (Memory), or total number of acquisition points.

14. 14 DSO Acquisition Modes Can Help Isolate Signal Details  Sample  When time per division is increased for a given displayed record length, displayed sample rate is decreased.  Peak Detect  Detects peaks between displayed samples.  Envelope  Accumulates peaks over multiple acquisitions.  High Resolution  Box car averages between displayed samples.  Average  Averages (normal or weighted) over multiple acquisitions.

15. 15 Digital Peak Detect Can Discover Glitches Between Displayed Samples Glitch Screen Trace Displayed Samples Glitch falls between sample points and would be missed in sample mode. Min Max Min More samples taken for peak detect. Max Min Glitch Screen Trace Max Displayed Samples Additional samples taken, min/max displayed, glitch captured in peak detect mode. MinMax

16. 16 Envelope Mode Can Accumulate Noise Average Mode Can Filter Out Noise  First Trace  Envelope Mode  Shows Maximum Noise  Second Trace  Average Mode  Reduces Noise

17. 17 Hi-Res Mode Is a Low Pass Filter That Improves Resolution for Each Acquisition As time/division is increased, better vertical amplitude resolution and noise removal can occur for a single triggered acquisition, at lower bandwidth. Used for High Resolution Acquisition Mode. Time Between Actual Samples Digitized Samples to be Averaged For the Next Display Point Averaged Display Points Actual Signal

18. 18 Digital Storage Oscilloscope Display Modes Can Help to Better See the Waveform  Dots  Replaces old acquired and displayed dots with new ones.  Vectors  Joins the acquisition dots in time with straight lines.  Persistence or Accumulate  Holds acquired and displayed dots for a defined amount of time. Infinite persistence holds acquired and displayed dots until erased.

19. 19 Dot Mode Displays Can Be Hard To Interpret

20. 20 Vector Mode, or Linear Interpolation Can Help To See The Real Signal

21. 21 Sampling and Digitizing What Happens To The Samples? 1 0 1 1 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 1 0 1 0 0 1 1 0 1 1 0..... Signal Sampling Digitizing Memory Storage (Sample, Hold) (Convert to Number) (Sequence Store) Record Length Sample Rate 1 0 1 1 1 0 0 1 Scope Screen Record Length Is Equal To The Total Number of Acquisition Points Acquisition Time Window =

22. 22 Real Time Digitizing (RTD) Acquires a Complete Waveform With One Trigger  Samples Single-shot Events in Real Time  With Samples Equally Spaced in Time  With Selectable Pre/Post Trigger Post-triggerPre-trigger Trigger

23. 23 Equivalent Time Digitizing (ETD) Acquires a Waveform Over Many Triggers  Uses repetitive sampling to reconstruct the shape of a high frequency repeating waveform over many triggered acquisition cycles  Allows bandwidth to increase to the DSO’s analog bandwidth

24. 24 Random Equivalent Time Digitizing Digitized samples are accumulated randomly before and after each trigger point. Time must be measured from the trigger point to the next sample in order to correctly place the digitized samples in the display memory. T1 S1S2S3

25. 25 Random Equivalent Time Digitizing Digitized samples are accumulated randomly before and after each trigger point. Time must be measured from the trigger point to the next sample in order to correctly place the digitized samples in the display memory. T1T2 S1S2S3S4S5S6

26. 26 Random Equivalent Time Digitizing Digitized samples are accumulated randomly before and after each trigger point. Time must be measured from the trigger point to the next sample in order to correctly place the digitized samples in the display memory. T1T2T3 S1S2S3S4S5S6S7S8S9

27. 27 Random Equivalent Time Digitizing  Multiple samples per trigger provide faster update rate.  Pre/post trigger capability is preserved. Digitized samples are accumulated randomly before and after each trigger point. Time must be measured from the trigger point to the next sample in order to correctly place the digitized samples in the display memory. T1T2T3 TN S1S2S3S4S5S6S7S8S9 S(T1)S(TN)

28. 28 Sequential Equivalent Time Digitizing Digitized samples are accumulated in time sequence after each trigger point with one sample per trigger. T1 S1

29. 29 Sequential Equivalent Time Digitizing Digitized samples are accumulated in time sequence after each trigger point with one sample per trigger. T1 S1 T2 S2

30. 30 Sequential Equivalent Time Digitizing Digitized samples are accumulated in time sequence after each trigger point with one sample per trigger. T1 S1 T2 S2 T3 S3

31. 31 Sequential Equivalent Time Digitizing  No Pre-trigger Digitized samples are accumulated in time sequence after each trigger point with one sample per trigger. T1 S1 T2 S2 T3 S3 S1SN TN

32. 32 What Happens When Too Few Samples Are Acquired? Aliasing or False Waveform Reproduction

33. 33 Single Event Bandwidth  Must Have Enough Sample Points to Reconstruct Waveform  Is Determined By the DSO’s Analog Bandwidth, Maximum Sample Rate, and Method of Waveform Reconstruction Amplitude Time

34. 34  Caused by Under Sampling the Signal  Cannot be Corrected With Digital Signal Processing Because the Maximum Sinewave Frequency In the Waveform Is More Than Half of the Digitized Sample Rate  Reproduces the Waveform Shape at a Lower Frequency Actual Aliasing Will Display False Waveform Reproduction Nyquist Theory Violated

35. 35 Slow Sample Rate Can Miss Important Signal Details Slow Sample Rate Misses High Speed Details Fast Sample Rate and/or Peak Detect Mode Captures High Speed Details Slower sample rate means more time between samples.

36. 36 Perceptual Aliasing Can Exist When Nyquist Theory Is Satisfied The Eye Cannot Interpret or Connect Dots in the Proper Sequence Improved by “Connecting the Dots”

37. 37 Perceptual Aliasing Can Be Reduced With Interpolation The Eye Cannot Interpret or Connect Dots in the Proper Sequence Improved by “Connecting the Dots” Sine Interpolation Linear Interpolation

38. 38 Analog Real-Time DPO Digital Storage More Waveform Capture Rate Displays More Details of Complex Signals More Waveform Capture Rate Will Capture More Waveform Anomalies On a Repeating Signal

39. 39 Waveform Capture Rate For Different Oscilloscopes Waveform Capture Rate (Waveforms/Second) Sweep Speed (Log Scale) 5 ms/div500 ps/div 0.1 1 10 100 1000 10000 100000 1000000 Typical DSO <100 Waveforms/Sec TDS7000 with DPX™ Enhanced DPO Acquisition >400,000 Waveforms/Sec Analog Real Time 2467B with Micro Channel Plate Up To 500,000 Waveforms/Sec TDS3000B with DPO Acquisition >3500 Waveforms/Sec TDS1000/TDS2000 >180 Waveforms/Sec

40. 40 Typical DSO Acquisition Misses Infrequent Waveform Information

41. 41 Fast Waveform Capture Rate Captures Infrequent Waveform Anomalies

42. 42 Triggering System Controls Allow for Isolating the Signal of Interest Source (Channel, Line) Coupling (AC/DC, HF/LF Rej) Horizontal System Trigger System Vertical System Internal Triggers External Trigger Level (P-P Auto, Norm) Slope Mode (Auto, TV, Single Sweep, Glitch, Width, Runt, Slew Rate, Setup/Hold, Logic) Holdoff Display System Signal ~

43. 43 Advanced Triggering Allows for Acquiring Specific Signal Details  Pulse (Width, Glitch, Runt, Slew Rate, Setup/Hold)  Logic (And, Or, Nand, Nor)  Timing (Four Channels)  State (Three Channels + One Clock)  TV/Video  Field Selection  Line Counting

44. 44 Pulse Width Triggering Accept only (or reject only) those triggers defined by pulse widths that are between two defined time limits, with +/- polarity selected. Time T1 (+) (-) T2 “Accept Only” is the same as “Within Limits” or “Equal To +/- 5%” “Reject Only” is the same as “Outside Limits” or “Not Equal To +/- 5%”

45. 45 Pulse Glitch Triggering Accept only (or reject only) those triggers defined by pulse widths that are below a defined time limit, with +/-/either polarity selected. Time (+) (-) (Either) “Accept Only” is the same as “Less Than” the defined time “Reject Only”is the same as “More Than” the defined time

46. 46 Pulse Runt Triggering Accept only those triggers defined by pulses that enter and exit between two defined amplitude thresholds, with +/-/either polarity selected. Time (+) (-) (Either)

47. 47 Slew Rate Triggering Trigger if the time interval from the low-to-high and/or high-to-low thresholds is slower (larger) than, or faster (smaller) than a specified time, with +/-/either polarity selected. Trigger If Faster Than Trigger If Slower Than Trigger If Faster Than Trigger If Slower Than High Threshold Low Threshold + Polarity Low-to-High Time Interval - Polarity High-to-Low Time Interval Time

48. 48 Setup/Hold Triggering Trigger if a + or - data edge (transition) occurs within the defined setup and hold time window of the positive (or negative, if selected) clock edge. Clock Source (Any Channel) Clock Level X X Setup TimeHold Time Data Level Trigger Reference Trigger Reference Hold Time Violation Setup Time Violation Data Source (Any Channel) Time

49. 49 A Breakthrough Solution The Digital Phosphor Oscilloscope  Digital Phosphor Oscilloscope An instrument that digitizes electrical signals and displays, stores, and analyzes three dimensions of signal information in real time. DPO Amp A/D Display uP DPX Waveform Imaging Processor Parallel Processing Acqui- sition Rasterizer Digital Phosphor Display Memory

50. 50 DPO Is Not A Persistence Mode  DPOs provide intensity grading, in real-time, as part of the acquisition system  Limited only by acquisition (trigger) rate  Provides intensity graded display information on dynamic signals  Captures dynamic signal variations, in real-time, enabling the user to see actual signal behavior  Allows vector waveforms  Rapidly builds a statistical representation of actual signal behavior Analog DSO Persistence DPO

51. 51 DPO Helps to Solve Today’s Measurement Challenges  Dynamic-Complex Signals  Example: Composite Video  Need: Accurate representation of dynamic-complex signal  Challenges: Make measurement on:  Multiple modulation types  Multiple periods  Highly dynamic signals  Detailed signal information over long time intervals  Distribution of occurrence information

52. 52 DPO Helps to Solve Today’s Measurement Challenges  Infrequent Event Capture  Example: Metastable event in high speed logic  Need: Detection and analysis of rare signal events  Challenges: Find and analyze infrequent faulty digital signals that have:  Low frequency of occurrence  Potentially non-repetitive characteristics  Vastly different durations from the primary signal  Highly dynamic characteristics  Unknown characteristics

53. 53 DPO Helps to Solve Today’s Measurement Challenges  Edge Jitter Evaluation  Example: High speed optical communications links  Need: Understanding of signal edge timing characteristics  Challengers: Analyze optical communications signals that have:  Highly dynamic characteristics  Distribution of occurrence information  Critical timing issues  Behaviors that require rapid statistical characterization

54. 54 DPO Helps to Solve Today’s Measurement Challenges  Long-Time Interval Capture  Example: Hard disk drive read channel  Need: Detecting subtle patterns of signal behavior over long time intervals  Challenges: Find and characterize disk drive signal faults and variations that have:  Rapid signal variations within long time window  Multiple time windows  Distribution of occurrence information

55. 55 DPO Helps to Solve Today’s Measurement Challenges  Complex Modulation  Example: Digital Cellular (Constellation Diagram)  Need: Detect phase and offset of I and Q signals  Challenges: Analyze and characterize digital cellular in- phase (I) and quadrature (Q) signal details that have:  Highly dynamic characteristics  Qualitative and quantitative information  Distribution of occurrence information  Dual axis bandwidth characteristics

56. 56 Choose the Right Oscilloscope Evaluate Your Needs

57. 57 Advantages of Digital Storage  Allows Up to 7 GHz Bandwidth Acquisitions for Single-shot Events  Finds Glitches with Peak Detect/Envelope  Finds Anomalies with DPX™ Enhanced DPO Acquisition  Acquires Waveforms Before the Trigger  Allows High Resolution Single-shot Averaging  Makes Accurate Timing Measurements  Provides Highest Bandwidth with Equivalent Time Digitizing  Enables Digital Signal Processing  Allows a Color Display

58. 58 Advantages of Digital Phosphor Oscilloscope (DPO)  Simulates the Characteristics of an Analog Real Time Oscilloscope’s Fast Waveform Capture Rate and Intensity Graded Display  Provides Intensity and/or Color Graded Display Showing Distribution of Amplitude Over Time, All In Real Time  Integrates An Image Over Many Real Time Traces of the Signal

59. 59 Advanced Triggering Can Provide:  Pulse Characteristic Selection  Width, Glitch, Runt, Slew Rate, Setup/Hold  Logic Condition Qualification  Filtering  HF/LF/Noise Reject  TV/Video Triggering

60. 60 Remember Probing and Vertical Amplifier Issues Such as:  Loading Effects  Differential Measurements  Current Sensing  High Voltage Breakdown  Transducer Characteristics  Vertical Range and Linearity  Vertical Sensitivity  SMT Connection

61. 61 For Ease of Use and Productivity Consider:  Human Interface Issues  Auto Set  Limit Testing  Cursors/Readout  Store/Recall Settings/Waveforms  Floppy Disk Storage  Color Displays  Programmability  Printer/Plotter/Computer Interfaces  Accessories

62. 62 Thank You For Your Attendance