EMI Debug using a Rohde&Schwarz Oscilloscope

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Ing. Leonardo Nanetti

Businnes Development manager

EMI Debug using a

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Outline

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EMI R&S Full portfolio solution overview

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Introduction of the Oscilloscope RTO main feature

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RTO FFT short review

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• Pre-Compliance • QA Testing implementation • Compliance Test • Design verifications • Specifications Testing • Product reviews

EMI Measurements in different design phases

How R&S Products contribute to EMI Measurements

Design Manufacturing

R&D Prototype Pre-Production Manufacturing

ו Top performance ו High accuracy ו Beyond specs

verifications ו Real- time spectrum ו Fast captures of

spurious noise

ו Correlate time & frequency domain ו Fast & accurate

measurements

ו Pre-certification EMI Test ו Fast & reliable

ו CISPR16 compliance ו High speed time

domain scan ו Hi performance ו Wide variety of measurements ו Good level of accuracy ו Reliable

ו Many meas. functions ו Entry level

ו Combo of EMI test receiver & spectrum ו Fully automated

ו Entry level EMI-EMC KIT

ו Good level of accuracy ו Reliable

ו Many meas. functions

Fastest EMI test receiver

- Time domain scan - Real time spectrum

- Frequency Mask Trigger - Spectrogram

- Persistence Mode

New

ESR3/7

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EMC Applications for Oscilloscopes

Radiated Interference

EMI

Conducted

Interference Power Quality

EN55011, EN55012, EN55013, EN55014, EN55015, EN55022, CISPR EN55011, EN55012, EN55013, EN55014, EN55015, EN55022, CISPR EN61000-3-2 EN60555-2 EN61000-3-3 EN60555-3 Power Harmonics Flicker Measurement EMS

ESD, EFT and

Burst Calibration EUT Monitoring

EN61000-4-2 EN61000-4-4 EN61000-4-5

EN61000-4-3

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R&S RTO Digital Oscilloscope

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R&S RTO Product Details

# 1. High Signal Fidelity

# 2. Leading Acquisition Rate # 3. Unique Digital Trigger # 4. Memory Speciality

# 5. Intuitive User Interface

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Created to be unique – RTO oscilloscopes

ı Fastest detection of rare signal faults

ı High accuracy and signal fidelity

Fastest

signal acquisition

& analysis

l Minimized trigger jitter

l New functionalities

l Optimized usage of touch screen display

l Intuitive user interface

New

benchmark

in usability

Most

innovative

trigger system

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R&S RTO Instrument Structure

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R&S RTO Digital Oscilloscope

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#1 High Signal Fidelity: Convincing Accuracy

Low Noise Front End

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Noise floor directly affects the sensitivity of the oscilloscope

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Noise floor is determined by the noise characteristics of the components in the signal path of the front end

 Variable Gain Amplifier (VGA)

 ADC

 Front end Layout and shielding

* Specified. Typical lower

ADCs

Front end

& Amplifiers Input channels

Channel-to-Channel Isolation > 60dB!

Benefit of lower noise: - Better Test Margin

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#1 High Signal Fidelity: Convincing Accuracy

Single Core ADC

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ADC-Picture

Single-core monolithic 10GS/s ADC vs Multiple ADCs in Single chip > 7 ENOBs !

High Accuracy without using interleaving!

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#1 High Signal Fidelity: Convincing Accuracy

Single Core ADC

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Effective Number of Bits (ENOB): A Number for Signal Fidelity

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Higher ENOB => lower quantization error and higher SNR

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Better accuracy Effective Bits (N) Quantization Levels Least Significant Bit ∆V 4 16 62.5 mV 5 32 31.3 mV 6 64 15.6 mV 7 128 7.8 mV 8 256 3.9 mV

Offset Error Gain Error Nonlinearity Error Aperture Uncertainty And Random Noise

+ + + ± ½ LDB Error Quantatized Digital Level Sample Points Analog Waveforms <

Ideal ADC vertical 8bits = 256 Quantatizing levels 8 bits Effective Number of Bits ! Ideal RTO Others

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#1 High Signal Fidelity: Convincing Accuracy

Multiple ADCs

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Conventional ADC-Design:

 Multiple ADCs used in parallel to increase sampling rate

 Errors in the phase delay and mismatch of the ADCs result in signal distortion Interleaving distortions In Time Domain Phase Errors Spurious Frequency Interleaving Artifact Signal Interleaving distortions In Frequency Domain

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#1 High Signal Fidelity: Convincing Accuracy

Input Sensitivity

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Do you expect your scope to perform with its Full Bandwidth Specification at all time? BNC Input Channel Amplifiers Position Input Coupling ADC Offset Vertical Input Sensitive Range Use with x10 Active Probe R&S RTO102x 50 Ω 1M Ω

>= 10 mV/div >=100 mV/div Full BW 500MHz

5 mV/div … 9.9 mV/div 50 mV/div … 99.9 mV/div Full BW 500MHz 2 mV/div … 4.99 mV/div 20 mV/div … 49.8 mV/div Full BW 500MHz 1 mV/div … 1.99 mV/div 10 mV/div … 19.9 mV/div Full BW 500MHz

True Accuracy => no BW limitation! True Resolution => no software magnification!

Benefit of dedicated amplifiers: Ability to analyze weak signal

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R&S RTO Digital Oscilloscope

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# 2. Leading Acquisition Rate

# 3. Unique Digital Trigger # 4. Memory Speciality

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#2 Market Leading Acquisition Rate

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Sees up to 20x more than traditional oscilloscopes

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=> Detect and also analyze rare signal 20x faster

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#2 Market Leading Acquisition Rate

R&S Enabler: RTC ASIC

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An Acquisition ASIC with high integration level (14 million gates) and massive parallel high-speed paths

R&S

®

RTC ASIC

ADC 8 bit, 10 Gbps 20x 8 bit, 500 Mbps

Acquisition Memory 160x 500 Mbps Memory 4x 8 bit Post-Processing Measurement, etc. Display

20x parallel: acquisition block

4x parallel: post-processing block

90nm technology 14 M gates ASIC

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#2 Market Leading Acquisition Rate

Data Decimation & Waveform Arithmetics

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Differentiated analysis with up to 3 simultaneous waveforms per channel

1 Channel

Original Waveform Envelope Waveform Hi-Res Waveform

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#2 Market Leading Acquisition Rate

Hardware Accelerated Analysis

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Most of analysis functions implemented in RTC ASIC & FPGA

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Acquisition rate remains high even during complicated signal analysis

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#2 Market Leading Acquisition Rate

Hardware Accelerated Analysis – Fast FFT

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FFT based spectrum analysis:

powerful & user-friendly

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Mask testing on FFT and

correlate with Time Domain

Mask violation -> Stop Acquisition HW overlapping FFT implementation =>

Very responsive and intensity modulated color display.

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R&S RTO Digital Oscilloscope

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# 2. Leading Acquisition Rate

# 3. Unique Digital Trigger # 4. Memory Speciality

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#3 Unique Digital Trigger System

Challenges of Analog Triggering

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Traditional: Analog trigger

=> has separate paths for signal and trigger different time-invariant

behavior of hardware components causes measurement errors

which cannot be compensated in real-time

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Comparison of Digital and Analog triggering architecture

Innovative Digital Trigger

Traditional

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#3 Unique Digital Trigger System

Challenges of Analog Triggering

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Different paths for signal and trigger cause measurement errors

ı Jitter can be corrected by using post processed DSP techniques and it slow down acquisition rate

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#3 Unique Digital Trigger System

R&S RTO Implementation Benefits

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Digital Triggering in Realtime is unique to RTO:

Real time, no DSP post correction!

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Benefits over Analog Triggering

 Industry leading Trigger Jitter <1ps rms without using DSP correction

 High trigger sensitivity down to 0.1 div for small signal amplitude

 Adjustable trigger hysteresis for stable trigger

 Flexible trigger filtering (user-defined low pass filter) for noisy signal

What you can see, you can trigger on!

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R&S RTO Digital Oscilloscope

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# 2. Leading Acquisition Rate # 3. Unique Digital Trigger

# 4. Memory Speciality

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#4 Memory Implementation Speciality

R&S RTO Unique – History View Mode

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Each waveform acquisition:

 is being stored in R&S RTO memory automatically

 can be playback anytime whenever is needed

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Note: RTO has the shortest Blind Time!

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R&S RTO Digital Oscilloscope

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#5 Intuitive User Interface

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Easy and fast access to all features and settings

 Flat menu hierarchy

 Cross links for easy access to belonging settings

 Fast access to often used function with toolbar

 Variable Transparent dialogue box

 Unlimited “Undo” button

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FFT as Basis for EMI Debugging with Oscilloscopes

Conventional FFT Implementation on a Scope

t Time Domain Record length T Windowing FFT Data acquisition Zoom (f₁…f₂) f Frequency Domain Dt = 1/F_s f Display f₂ f₁ F_max = F_s/2 S(f) S(f) x(t) Df = 1/T Disadvantages:

 Time domain settings define frequency domain

 Zoom in frequency domain does not give more details

 Correlated Time-Frequency Analysis not possible f₁ f₂

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FFT on the RTO

Spectrum Analyzer Use Model

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Use model: Frequency domain controls time domain

 Time domain parameters (record-length / sampling rate) automatically changed as necessary

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Downconversion FFT (DDC) zooms into frequency range before FFT

 Largely reduced record length, much faster FFT 500 MHz center, 10 MHz span: 1 GHz vs 20 MHz sampling frequency Time Domain t Record length T Data acquisition F_s=2B x(t) Frequency Domain f Display f2 f1 B=f₂-f₁ S(f) Df = 1/T Windowing FFT

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HW Zoom (DDC)

NCO

Decim- ation LP

Zoom happens here – before the FFT!

500 MHz center, 10 MHz span: Fs = 1 GS/s vs 20 MS/s

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What if we combine time and frequency domain?

Overlap FFT comes into play

Advantages:

• Analyse time-dependend spectrum

• Conventional (non-overlapping) FFT looses

information due to windowing  overlapping allows to capture everything

• Limit No of frames to ensure fast FFT processing • Note: FFT processing starts from the left!

FFT 1

FFT 2

FFT N Record length

Max frame count limit N = N_max Frame coverage up to here

10GS/s 18.96ns/div 1898 Samples 1 FFT (persistance disabled) 10GS/s 5 us/div 500 kSamples ~440 FFTs

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Gated FFT in the RTO

Practical Time-Frequency Analysis

50% overlap (default setting) Gated FFT:

|--- One complete Time-Domain capture ---|

Key Feature for EMI Debug!

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FFT – Further Settings, Further Features

Max-Hold*, Average, RMS

*Note: Envelope = Max Hold

Spectrum Units Correction factor

for a LISN (frequency independent,

e.g. 10 dB in this case)

Multiple FFTs

Green: Max-Hold

Purple: Current spectrum,

intensity graded

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What Accessory do we have?

31/05/2013 EMI debug using R&S RTO 33 R&S ® HZ-15

E- and H-field

30 MHz – 1 GHz

Can be used down to 100 kHz

Near-Field Probes

Hameg HZ530 E- and H-field Hameg HZ540/550 E- and H-field 100 kHz – 1 GHz 1 MHz – 3 GHz EUR 1.730,- EUR 788,- EUR 1.428,- / 1.848,-

LISN

Note: You need an isolation transformer for operating the LISN

R&S ENV216 Hameg HM 6050-2

EUR 1.038,- EUR 2-4k • Small size • No battery needed • Probe single circuit lines Note: No power supply included

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EMI Debugging: Equipment

Near-field sniffer Probes R&S ® HZ-15 E- and H-field R&S ® RTO 30 MHz – 1 GHz

Optional: R&S ® HZ-16

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EMI Debugging: Equipment

31/05/2013 EMI debug using R&S RTO

Near-field sniffer Probes R&S ® HZ-15

E- and H-field R&S ® RTO

30 MHz – 1 GHz

Optional: R&S ® HZ-16

Preamplifier

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Analyzing EMI Faults:

- Detecting possible signal problem due to EMI and sniff out the EMI source on the DUT

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Locating EMI weak points:

- Injecting EMI to detect possible signal faults to identify weaker DUT location

Electric field Probe Magnetic field Probe

Frequency Analysis Debugging

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EMI Debug with Near-Field Probes

Important Settings

Parameter Description

Record length Ensure that you capture enough (>= 500 kSamples)

Vertical settings 1 – 5 mV/div, 50 W Color table &

persistance Easily detect and distinquish CW signals and burst

Max. Frame Count Take care that you analyze the right part of the time signal Signal zoom & FFT

gating

Easily isolate spurious spectral components in time domain

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EMI voltage test: Basic test setup

> 8 0 cm 8 0 cm 30 to 40 cm 4 0 cm reference ground EUT test receiver AN wooden table > 2 0 0 >200 cm

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Precompliance Measurements with a Scope ???

• Conducted Emission using LISN • 9 kHz – 30 MHz

• FSV trace 1 = Max hold / Pos Peak RTO FFT1 = Normal mode • FSV trace 2 = Clear Write / Auto Peak RTO FFT2 = Envelope mode

EN55015Q

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Precompliance Measurements with a Scope ???

• Conducted Emission using LISN • 9 kHz – 1 MHz

• FSV trace 1 = Max hold / Pos Peak RTO FFT1 = Normal mode • FSV trace 2 = Clear Write / Auto Peak RTO FFT2 = Envelope mode

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FAQs … and Answers

Sensitivity

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DANL at 500 MHz, 120 kHz RBW, 50 W

Receiver DANL

RTO ~0 dBuV (1mV/div)1

ESR -7 dBuV (with Preamp)2

ESCI -4 dBuV (with Preamp)2

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How to show on the RTO using the FFT

 Note: Vertical Settings are 1mV/div, 50 W

 Sampling rate>=2xBW of the scope! Otherwise aliasing will increase noise!

1_Measured 2_{Datasheet value}

But:

A. RTO dynamic range

very limited compared to EMI receivers

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FAQs … and Answers

Noise Figure

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How to show on RTO

 Vertical Settings

 1mV/div, 50 W

 Enable FFT

 Use RMS detector

 Set center frequency

 Set RBW to e.g. 1 MHz

 Set unit to dBm

NF = Output noise – Input noise 

 RMS Power_dBm/RBW - (-174 dBm/Hz + 10xlog10 (RBW/Hz) ) = = -98 dBm – 60 dB + 174 dBm = 16 dB

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Limit Lines?



Use the mask tool

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6 dB EMI filter?



Not critical for precompliance, will change results only slightly.

FAQs … and Answers

What about …

Upper for limit line usage Mask definition in units of FFT

Upper region mask acting

as limit line

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EMI Debugging with Near-Field Probes

Use Cases

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A) Debugging problems that occurred during compliance test

31/05/2013 EMI debug using R&S RTO 45 CW Emission

Unknown broadband noise peak Noise from

power supply

 Identifying the location of the emission (down to signal paths)

 Understanding signal behaviour to identify the source

Problem in compliance test

Check if shielding etc enough

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EMI Source Identification

Advanced debugging – Using the RTO for the far-field

EMI Receiver, Spectrum Analyzer

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EMI/EMC

Further Use Cases

C) Use near-field probes

before

compliance test

 Only possible for EMC experienced design engineers

D) Near-field (small) EMI chambers

 Near-field – Far-field transformation with oscilloscopes  Only possible with two coherent channels

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EMI Debug

Customer Groups

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EMC test house engineers

 General EMI Debugging

 Far-field and near-field measurement

 Pulse calibration (ESD, EFT, Burst)

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In-house EMC labs

 See above

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Design engineers

A) After failed compliance B) Pre-Compliance

 Conducted emissions with LISN

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Summary

USPs of the RTO for EMI Debugging

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Sensitivity similar to EMI receivers

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Capture intermittent events with stop-on-mask-violation in frequency domain

 But, also time-domain trigger can help

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Analyze in frequency domain after capturing (changing RBW etc)

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Time-frequency correlation analysis (FFT gating)

 Discover cause of emission in time signal

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Flexible and easy-to-use FFT

 Use it like a spectrum analyzer

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