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Related Manuals for Tektronix XYZs
Summary of Contents for Tektronix XYZs
- Page 1 XYZs of Oscilloscopes...
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Page 3: Table Of Contents
XYZs of Oscilloscopes Primer Table of Contents Bandwidth Limit ......... . .20 Alternate and Chop Display Modes . - Page 4 XYZs of Oscilloscopes Primer The Complete Measurement System Oscilloscope Measurement Techniques Probes ........... .33 Voltage Measurements .
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Page 5: Introduction
The vocabulary and multiple-choice written exercises Tektronix representative, or visit www.tektronix.com. on oscilloscope theory and controls make this primer a useful classroom aid. No mathematical or electronics knowledge is necessary. -
Page 6: Signal Integrity
XYZs of Oscilloscopes Primer Signal Integrity Without some precautionary measures, high-speed problems can creep into otherwise conventional digital designs. If a circuit is The Significance of Signal Integrity experiencing intermittent failures, or if it encounters errors at voltage The key to any good oscilloscope system is its ability to accurately recon- and temperature extremes, chances are there are some hidden signal struct a waveform –... -
Page 7: Viewing The Analog Origins Of Digital Signals
XYZs of Oscilloscopes Primer The lumped circuit model has always been the basis of most calculations used to predict signal behavior in a circuit. But when edge speeds are more than four to six times faster than the signal path delay, the simple lumped model no longer applies. -
Page 8: Understanding Waveforms And Waveform Measurements
XYZs of Oscilloscopes Primer Sine Wave Damped Sine Wave Square Wave Rectangular Wave Triangle Wave Sawtooth Wave Pulse Step Figure 4. Sources of common waveforms. Complex Waveform shapes reveal a great deal about a signal. Any time you see a change in the height of the waveform, you know the voltage has changed. -
Page 9: Types Of Waves
XYZs of Oscilloscopes Primer Sine Wave Damped Sine Wave Sawtooth Wave Triangle Wave Figure 5. Sine and damped sine waves. Figure 7. Sawtooth and triangle waves. Square and Rectangular Waves The square wave is another common wave shape. Basically, a square wave is a voltage that turns on and off (or goes high and low) at regular intervals. -
Page 10: Step And Pulse Shapes
XYZs of Oscilloscopes Primer Pulse Step Pulse Train Complex Figure 8. Step, pulse and pulse train shapes. Figure 9. An NTSC composite video signal is an example of a complex wave. Step and Pulse Shapes Synchronous and Asynchronous Signals Signals such as steps and pulses that occur rarely, or non-periodically, When a timing relationship exists between two signals, those signals are are called single-shot or transient signals. -
Page 11: Waveform Measurements
XYZs of Oscilloscopes Primer 0 ° 270 ° 90 ° 180 ° ° +1 V Frequency 3 Cycles per Second = 3 Hz period –1 V 1 second Figure 10. Frequency and period of a sine wave. Figure 11. Amplitude and degrees of a sine wave. -
Page 12: Phase
XYZs of Oscilloscopes Primer Waveform Measurements with Digital Oscilloscopes Voltage Modern digital oscilloscopes have functions that make waveform measurements easier. They have front-panel buttons and/or screen-based Current menus from which you can select fully automated measurements. These include amplitude, period, rise/fall time, and many more. Many digital instruments also provide mean and RMS calculations, duty cycle, and other math operations. -
Page 13: The Types Of Oscilloscopes
XYZs of Oscilloscopes Primer Display Vertical System System Vertical Attenuator Amplifier Trigger System Horizontal System Probe Sweep Horizontal Generator Amplifier Ramp Time Base Figure 13. The architecture of an analog oscilloscope. The Types of Oscilloscopes horizontally across the display, tracing the waveform on the screen. The... -
Page 14: Digital Oscilloscopes
XYZs of Oscilloscopes Primer 1010 0001 0010 0101 Triggered Display Untriggered Display Analog Oscilloscopes Digital Oscilloscopes Samples Trace Signals Signals and Construct Displays Figure 14. The trigger stabilizes a repetitive waveform, creating a clear picture of the signal. Figure 15. Analog oscilloscopes trace signals, while digital oscilloscopes sample signals and construct displays. -
Page 15: Digital Storage Oscilloscopes
XYZs of Oscilloscopes Primer Display Acquisition Display DeMUX Memory Memory Figure 16. The serial-processing architecture of a digital storage oscilloscope (DSO). Digital Storage Oscilloscopes Serial-processing Architecture Like an analog oscilloscope, a DSO’s first (input) stage is a vertical A conventional digital oscilloscope is known as a digital storage amplifier. - Page 16 XYZs of Oscilloscopes Primer The sample points from the ADC are stored in acquisition memory as waveform points. Several sample points may comprise one waveform point. Together, the waveform points comprise one waveform record. The number of waveform points used to create a waveform record is called the record length.
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Page 17: Digital Phosphor Oscilloscopes
XYZs of Oscilloscopes Primer • Snapshots of the Digital Phosphor contents are periodically sent directly to the display without stopping the acquisition. Digital Display Phosphor • Waveform math, measurements, and front panel control are executed by the microprocessor parallel to the integrated acquisition/display system. - Page 18 XYZs of Oscilloscopes Primer A DPO faithfully emulates the best display attributes of an analog oscilloscope, displaying the signal in three dimensions: time, amplitude and the distribution of amplitude over time, all in real time. Unlike an analog oscilloscope’s reliance on chemical phosphor, a DPO uses a purely electronic digital phosphor that’s actually a continuously updated...
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Page 19: Digital Sampling Oscilloscopes
XYZs of Oscilloscopes Primer Sampling Bridge 50 Ω Input Amplifier (3 V Max) Figure 20. The architecture of a digital sampling oscilloscope. Digital Sampling Oscilloscopes When measuring high-frequency signals, the oscilloscope may not be able to collect enough samples in one sweep. A digital sampling oscilloscope is an ideal tool for accurately capturing signals whose frequency components are much higher than the oscilloscope’s sample... -
Page 20: The Systems And Controls Of An Oscilloscope
XYZs of Oscilloscopes Primer The front panel of an oscilloscope is divided into three main sections labeled vertical, horizontal, and trigger. Your oscilloscope may have other sections, depending on the model and type – analog or digital – as shown in Figure 22. See if you can locate these front-panel sections in Figure 22, and on your oscilloscope, as you read through this section. -
Page 21: Position And Volts Per Division
XYZs of Oscilloscopes Primer DC Coupling of a V Sine AC Coupling of the Same Signal Wave with a 2 V DC Component Figure 23. AC and DC input coupling. Position and Volts per Division Input Coupling The vertical position control allows you to move the waveform up and Coupling refers to the method used to connect an electrical signal from down exactly where you want it on the screen. -
Page 22: Bandwidth Limit
XYZs of Oscilloscopes Primer Chop Mode: Segments of Channel 1 and Attention Mode: Channel 1 and Channel 2 Channel 2 Drawn Alternately Drawn Alternately Drawn First Drawn Second Figure 24. Multi-channel display modes. Bandwidth Limit Alternate mode draws each channel alternately – the oscilloscope... -
Page 23: Horizontal System And Controls
XYZs of Oscilloscopes Primer Acquisition Controls Digital oscilloscopes have settings that let you control how the acquisition system processes a signal. Look over the acquisition options on your digital oscilloscope while you read this description. Figure 25 shows you an example of an acquisition menu. - Page 24 XYZs of Oscilloscopes Primer Sampled point displayed by the DSO The glitch you will not see Figure 26. Sample rate varies with time base settings – the slower the time base setting, the slower the sample rate. Some digital oscilloscopes provide peak detect mode to capture fast transients at slow sweep speeds.
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Page 25: Starting And Stopping The Acquisition System
XYZs of Oscilloscopes Primer Sampling is like taking snapshots. Each snapshot corresponds to a 100 ps specific point in time on the waveform. These snapshots can then be arranged in the appropriate order in time so as to reconstruct the 1 Volt input signal. -
Page 26: Real-Time Sampling
XYZs of Oscilloscopes Primer Waveform Constructed with Record Points Sampling Rate Figure 29. Real-time sampling method. Real Time Sampled Display Input Signal Figure 30. In order to capture this 10 ns pulse in real-time, the sample rate must be high enough to accurately define the edges. -
Page 27: Real-Time Sampling With Interpolation
XYZs of Oscilloscopes Primer Waveform Constructed with Record Points Sine Wave Reproduced using Sine x/x Interpolation 1st Acquisition Cycle 2nd Acquisition Cycle Sine Wave Reproduced using Linear Interpolation 3rd Acquisition Cycle nth Acquisition Cycle Figure 31. Linear and sin x/x interpolation. -
Page 28: Random Equivalent-Time Sampling
XYZs of Oscilloscopes Primer Equivalent Time Sequential Sampled Display Figure 33. In random equivalent-time sampling, the sampling clock runs Figure 34. In sequential equivalent-time sampling, a single sample is taken asynchronously with the input signal and the trigger. for each recognized trigger after a time delay which is incremented after each cycle. -
Page 29: Position And Seconds Per Division
XYZs of Oscilloscopes Primer Position and Seconds per Division XY Mode The horizontal position control moves the waveform left and right to Most analog oscilloscopes have an XY mode that lets you display an exactly where you want it on the screen. -
Page 30: Trigger System And Controls
When you are using more than four channels to trigger on signals, a Trigger controls allow you to stabilize repetitive waveforms and capture logic analyzer is the ideal tool. Please refer to Tektronix’ XYZs of Logic single-shot waveforms. Analyzers primer for more information about these valuable test and The trigger makes repetitive waveforms appear static on the oscilloscope measurement instruments. -
Page 31: Trigger Position
XYZs of Oscilloscopes Primer Slew Rate Triggering. High frequency signals with slew rates Runt Pulse Triggering. Runt triggering allows you to faster than expected or needed can radiate troublesome capture and examine pulses that cross one logic threshold, energy. Slew rate triggering surpasses conventional edge but not both. -
Page 32: Trigger Level And Slope
XYZs of Oscilloscopes Primer Trigger Level and Slope Triggering on the Positive Slope with the Level Set to 3 V The trigger level and slope controls provide the basic trigger point Positive Negative definition and determine how a waveform is displayed, as illustrated... -
Page 33: Trigger Holdoff
XYZs of Oscilloscopes Primer Figure 37. Trigger holdoff. Trigger Holdoff Display System and Controls An oscilloscope’s front panel includes a display screen and the knobs, Sometimes getting an oscilloscope to trigger on the correct part of a signal buttons, switches, and indicators used to control signal acquisition and requires great skill. -
Page 34: Other Oscilloscope Controls
XYZs of Oscilloscopes Primer Rise Time Marks Channel 1 Display ADD Mode: Channel 1 and Channel 2 Combined Channel 2 Display Minor Marks Major Division Figure 38. An oscilloscope graticule. Figure 39. Adding channels. Display systems vary between analog oscilloscopes and digital Other Oscilloscope Controls oscilloscopes. -
Page 35: The Complete Measurement System
A description of the types of probes follows. Please refer to to choose a probe that, when paired with your oscilloscope, exceeds the signal bandwidth by 5 times. Tektronix’ ABCs of Probes primer for more information about this essential component of the overall measurement system. www.tektronix.com... -
Page 36: Passive Probes
XYZs of Oscilloscopes Primer Because it attenuates the signal, the 10X attenuator probe makes it difficult to look at signals less than 10 millivolts peak-to-peak. The 1X probe is similar to the 10X attenuator probe but lacks the attenuation circuitry. Without this circuitry, more interference is introduced to the circuit being tested. -
Page 37: Active And Differential Probes
XYZs of Oscilloscopes Primer Figure 42. High-performance probes are critical when measuring the Figure 43. Differential probes can separate common-mode noise from fast clocks and edges found in today’s computer buses and data the signal content of interest in today’s fast, low-voltage applications –... -
Page 38: Probe Accessories
Please refer to Tektronix’ ABCs of Probes primer for more information screen. Some probe interfaces also recognize the type of probe – that is, about probe accessories. -
Page 39: Performance Terms And Considerations
XYZs of Oscilloscopes Primer } 3% 70 (-3dB) Normalized Frequency Figure 46. Oscilloscope bandwidth is the frequency at which a sinusoidal input signal is attenuated to 70.7% of the signal’s true amplitude, known as the –3 dB point. Figure 47. The higher the bandwidth, the more accurate the reproduction... -
Page 40: Rise Time
XYZs of Oscilloscopes Primer Typical Signal Calculated Rise Time Signal Logic Family Bandwidth 2 ns 175 MHz CMOS 1.5 ns 230 MHz 1 ns 350 MHz LVDS 400 ps 875 MHz 100 ps 3.5 GHz GaAs 40 ps 8.75 GHz Figure 49. -
Page 41: Sample Rate
XYZs of Oscilloscopes Primer How do you calculate your sample rate requirements? The method differs based on the type of waveform you are measuring, and the method of signal reconstruction used by the oscilloscope. In order to accurately reconstruct a signal and avoid aliasing, Nyquist theorem says that the signal must be sampled at least twice as fast as its highest frequency component. -
Page 42: Waveform Capture Rate
XYZs of Oscilloscopes Primer Figure 51. A DSO provides an ideal solution Figure 52. A DPO enables a superior level of Figure 53. Capturing the high frequency for non-repetitive, high-speed, multi-channel insight into signal behavior by delivering detail of this modulated 85 MHz carrier digital design applications. -
Page 43: Triggering Capabilities
XYZs of Oscilloscopes Primer Modern oscilloscopes allow you to select record length to optimize the Vertical Sensitivity level of detail needed for your application. If you are analyzing an Vertical sensitivity indicates how much the vertical amplifier can amplify extremely stable sinusoidal signal, you may need only a 500-point a weak signal –... -
Page 44: Connectivity
XYZs of Oscilloscopes Primer Analysis Software Dual Monitor Browser Storage Word Processor Windows Desktop Drive Spread- sheet Open Windows Platform Wireless E-mail Figure 55. A TDS3000 Series oscilloscope provides a wide Serial/ array of communications interfaces, such as a standard... -
Page 45: Expandability
XYZs of Oscilloscopes Primer Figure 56. The TDSJIT2 optional software Figure 57. Equip the TDS700 Series oscillo- Figure 58. The TDS3SDI video module makes package for the TDS7000 Series oscillo- scope with the TDSCEM1 application module the TDS3000 Series oscilloscope a fast, tell-all scope is specifically designed to meet jitter for communications mask compliance testing. -
Page 46: Ease-Of-Use
Please refer to The Complete Measurement System under the Systems and Controls of the Oscilloscope section, or the Tektronix’ ABCs of Probes primer, for additional information. www.tektronix.com... -
Page 47: Operating The Oscilloscope
XYZs of Oscilloscopes Primer Operating the Oscilloscope Setting Up This section briefly describes how to set up and start using an oscilloscope – specifically, how to ground the oscilloscope, set the controls in standard positions, and compensate the probe. Proper grounding is an important step when setting up to take measure- ments or work on a circuit. -
Page 48: Setting The Controls
Please refer to The Complete Measurement System under the Systems attach the probes. Most oscilloscopes have at least two input channels and and Controls of the Oscilloscope section, or the Tektronix’ ABCs of each channel can display a waveform on the screen. Multiple channels are Probes, for additional information. -
Page 49: Compensating The Probe
XYZs of Oscilloscopes Primer Probe Compensated Correctly Probe Note Proper Adjustment Amplitude of a Signal 1 MHz Test Signal Probed Undercompensated Note Reduced Probe Amplitude of a Adjustment 1 MHz Test Signal Signal Probed Overcompensated Note Increased Probe Amplitude of a... -
Page 50: Oscilloscope Measurement Techniques
XYZs of Oscilloscopes Primer Voltage Peak Voltage Peak-to-Peak RMS Voltage Zero Volts Figure 66. Voltage peak (V ) and peak-to-peak voltage (V When you compensate the probe, always attach any accessory tips you Voltage Measurements will use and connect the probe to the vertical channel you plan to use. This... -
Page 51: Time And Frequency Measurements
XYZs of Oscilloscopes Primer Take Amplitude Measurements at Center Vertical Graticule Line Take Time Measurements at Center Horizontal Graticule Line Figure 67. Measure voltage on the center vertical graticule line. Figure 68. Measure time on the center horizontal graticule line. -
Page 52: Phase Shift Measurements
XYZs of Oscilloscopes Primer Phase Shift Rise Time X:Y Ratio Fall Time Frequency 100% 0° 45° 90° 180° 270° 360° 22° 30° Voltage 0° 45° 90° 135° 180° Pulse Width 0° 15° 30° 60° 90° 120° 0° 11° 15° 22° 30°... -
Page 53: Written Exercises
XYZs of Oscilloscopes Primer Written Exercises This section contains written exercises that cover information in this book. The exercises are divided into two parts, Part I and Part II. Part I covers information presented in these sections: The Oscilloscope Performance Terms and Considerations... -
Page 54: Application Exercises
XYZs of Oscilloscopes Primer Part I 5. On an oscilloscope display: Voltage is on the vertical axis and time is on the The Oscilloscope horizontal axis. Performance Terms and Considerations A straight diagonal trace means voltage is changing at a steady rate. -
Page 55: Vocabulary Exercises
XYZs of Oscilloscopes Primer Part II The Systems and Controls of an Oscilloscope Operating the Oscilloscope Measurement Techniques Vocabulary Exercise – Write the letter of the definitions in the right column next to the correct words in the left column. -
Page 56: Application Exercises
XYZs of Oscilloscopes Primer Part II 5. The trace rotation control is useful for: Scaling waveforms on the screen. The Systems and Controls of an Oscilloscope Detecting sine wave signals. Operating the Oscilloscope Aligning the waveform trace with the screen’s horizontal axis on an analog oscilloscope. -
Page 57: Answer Key
XYZs of Oscilloscopes Primer 11. The two most basic measurements you can make with an oscillo- Answer Key scope are: This section provides the answers to all written exercises Time and frequency measurements. in the previous sections. Time and voltage measurements. -
Page 58: Glossary
XYZs of Oscilloscopes Primer Glossary Acquisition Mode – Modes that control how waveform points are Coupling – The method of connecting two circuits together. Circuits con- produced from sample points. Some types include sample, peak detect, nected with a wire are directly coupled (DC); circuits connected through a hi res, envelope, and average. - Page 59 XYZs of Oscilloscopes Primer Direct Current (DC) – A signal with a constant voltage and/or current. Horizontal Sweep – The action of the horizontal system that causes a Also used to indicate signal coupling type. waveform to be drawn. Division – Measurement markings on the cathode-ray tube (CRT) graticule Intensity Grading –...
- Page 60 XYZs of Oscilloscopes Primer Phase Shift – The difference in timing between two otherwise Signal Integrity – The accurate reconstruction of a signal, determined by similar signals. the systems and performance considerations of an oscilloscope, in addition to the probe used to acquire the signal.
- Page 61 XYZs of Oscilloscopes Primer Trigger Slope – The slope that a trigger source signal must reach before the trigger circuit initiates a sweep. Vertical Resolution (Analog-to-Digital Converter) – An indication of how precisely an analog-to-digital converter (ADC) in a digital oscilloscope can convert input voltages into digital values, measured in bits.
- Page 62 XYZs of Oscilloscopes Primer Notes: www.tektronix.com...
- Page 64 Information in this publication supersedes that in all previously published material. Specification and price change privileges reserved. TEKTRONIX and TEK are registered trade- marks of Tektronix, Inc. All other trade names referenced are the service marks, trademarks or registered trademarks of their respective companies.