Scope Technology Improvements

Save Time and Money by Upgrading Your Test Equipment

Presented by Mike Hoffman

How Have Oscilloscopes Improved?

“Banner” Specifications

Bandwidth

Sample Rate

Memory Depth

Waveform Update Rate

Number of Channels

Other Important Factors

Triggering

Display Quality

Serial Bus Applications

Measurements & Analysis

Connectivity & Documentation

Probing

Total Cost of Ownership

Handheld Most portable Battery operation Lowest performance

PC-based Module Lowest costEasy connectivity

to other analysis tools

Limited performance

Portable Benchtopwith embedded O.S. Most pervasive Best debug tool Easiest to use Limited analysis

Windows-based Mainframe Highest performance Most analysis Most expensive Windows only

Select the format that meets your performance requirements, use-model, and budget.

What Oscilloscopes are Out There?Form Factor Considerations

#1 – BandwidthHow much do I need?

Step #2: Determine highest signal frequency content (fKnee).

fKnee = 0.5/RT (10% - 90%) fKnee = 0.4/RT (20% - 80%)

Step #3: Determine degree of required measurement accuracy.

Required Accuracy

Gaussian Response

20% BW = 1.0 X fKnee

10% BW = 1.3 X fKnee

3% BW = 1.9 X fKnee

Step #4: Calculate required bandwidth.

Step #1: Determine fastest rise/fall times of device-under-test.

Source: Dr. Howard W. Johnson, “High-speed Digital Design – A Handbook of Black Magic”

#1 – BandwidthHow much do I need?

fknee = (0.5/1 ns) = 500 MHz

3% Accuracy: Scope Bandwidth = 1.9 x 500 MHz = 950

MHz

20% Accuracy: Scope Bandwidth = 1.0 x 500 MHz = 500

MHz

Example (using the more accurate method):

Determine the minimum required bandwidth of an oscilloscope (assume Gaussian frequency response) to accurately measure digital signals that have rise times as fast as 1 ns (10-90%):

Agilent’s Recommendation:

Select a scope that has sufficient bandwidth to accurately capture the highest frequency content of

your signals.

#2 – Memory DepthHow do scopes manage memory?

Scopes with deep acquisition memory can capture longer time spans while also sampling at a higher rate.

Scopes automatically adjust their sample rates based on the timebase setting and memory depth of the scope.

Deep memory Usually a manual selectionUsually slows update ratesUsually adds cost

Agilent’s MegaZoom IV Technology automatically turns on deeper memory when the scope is used on slower timebase settings in order to sustain faster sample rates, while also providing responsive waveform update rates.

#2 – Memory DepthHow much memory do I need?

Step 1: Determine required sample rate (4x BW of signal)

Step 2: Determine longest time-span to acquire

Step 3: Required Memory Depth = Time-span/Sample Interval

Example:Required Sample Rate = 2 GSa/sSample Interval = 1/SR = 500 psLongest Time Span = 2 ms (200 µs/div)Required Memory Depth

= 2 ms / 500 ps= 4 MB

Agilent’s Recommendation:

Select a scope that has sufficient acquisition memory to capture your most complex signals

with high resolution.

#2 – Memory DepthSegmented MemorySegmented Memory optimizes a scope’s available acquisition memory by only capturing important segments of an input signal. It is ideal for capturing bursts of signals such as packetized serial data that have long signal idle times between packets.

Example:Number of segments captured: 1000Time-tag of last segment: 3 secEquivalent memory depth: 120 MB

Segment #1Time-tag = 0.0 s

Segment #2Time-tag = 2.99 ms

Segment #1000Time-tag = 2.99 s

Improves scope usability

Improves scope display quality

Improves scope probability of capturing infrequent events

#3 – Waveform Update RateWhy are fast update rates important?

dead-time (děd’-tīm) n. 1.) Re-arm and waveform processing time between acquisition cycles. 2.) May be many orders or magnitude larger than the acquisition time.

#3 – Waveform Update RateWhat is dead time?

% Dead-time = 95%Glitch Capture Probability = 91.8%

% Dead-time = 99.995%Glitch Capture Probability = 0.25%

No Glitches Captured

Ex #1: Update Rate = 1000 waveforms/sec Ex #2: Update Rate = 1,000,000 waveforms/sec

Multiple Glitches Captured

Glitch Rate = 10 occurrences/secViewing Window = 50 ns (5 ns/div)Observation Time = 5 seconds

#3 – Waveform Update RateInfrequent Glitch Capture Comparison

#3 – Waveform Update RateMask Testing and Six Sigma

#4 – Number of ChannelsHow many channels do I need?

2 & 4 Channel DSOs are common

> 4 Channel DSOs are less common and expensive

But many of today’s complex digital systems require measurements on more than 4 channels simultaneously.

Solution: Mixed Signal Oscilloscope (MSO)

• What is an MSO?

Time-correlated display of scope and logic-timing waveforms

Full scope functionality with ease-of-use

Advanced logic triggering

MSOs combine ALL the measurement capabilities of an oscilloscope, with SOME of the measurement

capabilities of a logic analyzer.

Agilent’s Recommendation:

Select a scope that has a sufficient number of channels of acquisition so that you can perform critical time-

correlated measurements.

#4 – Number of ChannelsMixed Signal Oscilloscopes

Think of oscilloscope “triggering” as “synchronized picture taking”.

One waveform “picture” consists of many consecutive digitized samples.

“Picture Taking” must be synchronized to a unique point on the waveform that repeats.

Most common oscilloscope triggering is based on synchronizing acquisitions (picture taking) on a rising or falling edge of a signal at a specific voltage level.

Triggering is often the least understood function of a scope, but is one of the most important capabilities

that you should understand.

A photo finish horse race is analogous to

oscilloscope triggering

#5 – TriggeringHow does it work?

Default trigger location (time zero) on DSOs = center-screen (horizontally)

Only trigger location on older analog scopes = left side of screen

Trigger = Rising edge @ +2.01 V

Trigger Point

Positive TimeNegative Time

#5 – TriggeringEdge triggering

Example: Trigger on 1110 0110 (E6HEX)

Some oscilloscopes can trigger on complex parallel bus conditions using Pattern triggering (especially useful on MSOs)

#5 – TriggeringAdvanced MSO Triggering

Example: Trigger if setup time < 25 ns

Some oscilloscopes can trigger on clock-to-data timing violations using Setup & Hold Time triggering

Edge triggering reveals random shifting data edge

Infrequent timing shift

#5 – Triggering

Some oscilloscopes can trigger using predefined zones, often called visual triggering or zone triggering.

#5 – TriggeringZone Triggering

Agilent’s Recommendation:

Select a scope that has the types of advanced triggering that you may need to help you isolate waveform acquisitions on your most complex signals.

#5 – Triggering

#6 – Display Quality

DSO with 2 levels of intensity gradation

Traditional analog scope

DSO with 64 levels of intensity gradation

Factors to consider…

Number of levels of intensity modulation

Display size

Display resolution (VGA, XGA, etc.)

Color or Monochrome

Agilent’s Recommendation:

Select a scope that provides multiple levels of trace intensity gradation in order to display subtle waveform details and signal anomalies.

Intensity gradation can reveal relative jitter and noise

distribution on digital signals

#6 – Display Quality

#7 – Serial Bus Applications

I2C SPI RS232/UART CAN LIN FlexRay MIL-STD 1553 ARINC 429 I2S USB

Serial buses are used pervasively in most of today’s designs to communicate: Between functional blocks Chip to chip Board to IO Remote sensor to control

Protocol Decode

Lister/Event Table

Time-aligned Decode Trace

Frame ID = 07FFrame Type = Remote Transfer Request (RMT)Data Length Code = 1Data = N/ACRC = 60D9

#7 – Serial Bus ApplicationsToday’s Decode Method

Protocols Supported?

Decoding MethodHardware-based?Software-based?

Serial TriggeringAddress/Frame ID?Data contents?Errors?

Post-acquisition Search & Navigation?

Serial Eye-diagram Mask Testing?Agilent’s Recommendation:

Select a scope that can trigger on and decode serial bus protocols to help you debug your designs faster.

#7 – Serial Bus ApplicationsThings to Consider

Time & Voltage Cursors

Parametric MeasurementsRise Time, Vpp, Pulse width, etcMeasurement statisticsUser-selectable threshold settings

Waveform MathSum, Subtract, Integrate, FFT, etc.

Pass/Fail Mask Testing

Application-specific Compliance Testing

Agilent’s Recommendation:

Select a scope that can automatically perform your required measurements and waveform analysis to help you characterize

your designs faster.

#8 – Measurements and AnalysisThings to Consider

Parametric Measurements

Pass/Fail Mask Testing

Waveform Math (FFT)

Application-specific Compliance Testing

#8 – Measurements and AnalysisAdvanced Examples

GP-IB

RS-232

USB

LAN

Automated testing requires that your scope be fully programmable and linked to a PC via:

Supported on most older DSOs (sometimes optional)

Supported on most newer DSOs (sometimes optional)

All of Agilent’s oscilloscopes come standard with USB and/or LAN

connectivity.

#9 – Connectivity and DocumentationProgramming the Scope Remotely

Saving Images (screen-shots)

BMP, TIF, PNG

Saving data (waveforms, protocol decodes)

CSV, ASCII, BINAgilent’s Recommendation:

Select a scope that meets your particular connectivity and documentation

requirements.

For documenting test results, you can transfer waveform data and/or images to a PC or save them to a USB memory stick on the scope in various formats on most of today’s digital oscilloscopes.

#9 – Connectivity and DocumentationDocumenting your Results

Types of Oscilloscope Probes:Standard passive probesTypically included with scopeLimited to 500 MHz BW

High frequency passive probesBut with low Z input

High frequency active probes

Differential active probes

High voltage probes

Current probes

Agilent’s Recommendation:

Select a scope from a vendor that can also provide the variety of specialty probes that you may require.

Scope measurements are only as good as the what the probe can deliver to the scope’s

inputs.

#10 – Probing

#11 – Total Cost of OwnershipCalibration, Repair, Replacement, Accessories, Upgrades, Software

Sticker price is only half the battle…

#11 – Total Cost of OwnershipMaintenance

Sticker price is only half the battle…

Maintenance ConsiderationsCalibration

Down time Cost

Reliability MTBF Warranty

#11 – Total Cost of OwnershipUpgrades

Sticker price is only half the battle…

Upgrade ConsiderationsProbesMore BandwidthMore ChannelsMeasurement Apps

Application Notes Publication #

Evaluating Oscilloscope Fundamentals 5989-8064EN

Evaluating Oscilloscope Bandwidths for your Applications 5989-5733EN

Evaluating Oscilloscope Sample Rates vs. Sampling Fidelity 5989-5732EN

Evaluating Oscilloscopes for Best Waveform Update Rates 5989-7885EN

Evaluating Oscilloscopes for Best Display Quality 5989-2003EN

Evaluating Oscilloscope Vertical Noise Characteristics 5989-3020EN

Evaluating Oscilloscopes to Debug Mixed-signal Designs 5989-3702EN

Evaluating Oscilloscope Segmented Memory for Serial Bus Applications 5990-5817EN

http://cp.literature.agilent.com/litweb/pdf/xxxx-xxxxEN.pdf

Insert pub # in place of “xxxx-xxxx”

Getting More Information

Scope

Series

Bandwidth Sample Rate (Max)

Memory

Depth

MSO Option

Function

Gen Opt.

Segmented

Memory Opt.

Serial Bus

Options

Advanced

Triggering

2000X

70 to 200 MHz 2 GSa/s 1M 8-Ch Yes 250

Segs Yes Serial only

3000X

100 to 500 MHz 4 GSa/s 4M 16-Ch Yes 1000

Segs Yes Optional

4000X

200 MHz to 1.5 GHz 5 Gsa/s 4M 16-Ch Dual 1000

Segs Yes Standard

Engineered for Best Signal Visibility

InfiniiVision 2000 X-Series InfiniiVision 3000 X-Series

Agilent InfiniiVision X-Series Oscilloscopes

InfiniiVision 4000 X-Series

Thank You For Attending!

Questions or Comments?

Email the moderator, Nicole VanWert: nvanwert@Transcat.com

Or contact Transcat sales at:

800-828-1470

www.Transcat.com

sales@Transcat.com