EMI Debug using a Rohde&Schwarz Oscilloscope

Transcription

1 EMI Debug using a Rohde&Schwarz Oscilloscope Ing. Leonardo Nanetti Businnes Development manager

2 Outline ı EMI R&S Full portfolio solution overview ı Introduction of the Oscilloscope RTO main feature ı RTO FFT short review ı EMI Debuggung use cases and demo 31/05/2013 EMI debug using R&S RTO 2

3 EMI Measurements in different design phases How R&S Products contribute to EMI Measurements R&D Design verifications Specifications Testing Product reviews Design Prototype Pre-Production Pre-Compliance QA Testing implementation Compliance Test Manufacturing Manufacturing New ESR3/7 ו Top performance ו High accuracy ו Beyond specs verifications ו Real- time spectrum ו Fast captures of spurious noise ו CISPR16 compliance ו High speed time domain scan ו Pre-certification EMI Test ו Fast & reliable ו Correlate time & frequency domain ו Fast & accurate measurements ו Entry level ו Combo of EMI test receiver & spectrum ו Fully automated ו Entry level EMI-EMC KIT ו Hi performance ו Wide variety of measurements ו Good level of accuracy ו Reliable ו Many meas. functions 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 31/05/2013 EMI debug using R&S RTO 3

4 EMC Applications for Oscilloscopes EMI EMS Radiated Interference Conducted Interference Power Quality ESD, EFT and Burst Calibration EUT Monitoring EN55011, EN55012, EN55013, EN55014, EN55015, EN55022, CISPR EN55011, EN55012, EN55013, EN55014, EN55015, EN55022, CISPR EN EN EN EN EN EN EN EN Power Harmonics Flicker Measurement RTO: An powerful tool for EMI/EMS debugging and precompl. applications 31/05/2013 EMI debug using R&S RTO 4

5 R&S RTO Digital Oscilloscope ı R&S RTO Product Details # 1. High Signal Fidelity # 2. Leading Acquisition Rate # 3. Unique Digital Trigger # 4. Memory Speciality # 5. Intuitive User Interface 31/05/2013 EMI debug using R&S RTO 5

6 Created to be unique RTO oscilloscopes ı Fastest detection of rare signal faults ı High accuracy and signal fidelity Fastest signal acquisition & analysis l Optimized usage of touch screen display l Intuitive user interface New benchmark in usability l Minimized trigger jitter l New functionalities Most innovative trigger system

7 R&S RTO Instrument Structure 31/05/2013 EMI debug using R&S RTO 7

9 #1 High Signal Fidelity: Convincing Accuracy Low Noise Front End ı Noise floor directly affects the sensitivity of the oscilloscope ı 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 ADCs * Specified. Typical lower Benefit of lower noise: - Better Test Margin Front end & Amplifiers Input channels Channel-to-Channel Isolation > 60dB! 31/05/2013 EMI debug using R&S RTO 9

10 #1 High Signal Fidelity: Convincing Accuracy Single Core ADC ı ADC-Picture RTO Single Core ADC Single-core monolithic 10GS/s ADC vs Multiple ADCs in Single chip > 7 ENOBs! High Accuracy without using interleaving! 31/05/2013 EMI debug using R&S RTO 10

11 #1 High Signal Fidelity: Convincing Accuracy Single Core ADC ı Effective Number of Bits (ENOB): A Number for Signal Fidelity ± ½ LDB Error Effective Bits (N) Quantization Levels Least Significant Bit V mv Quantatized Digital Level Analog Waveforms Others mv mv Ideal ADC vertical 8bits = 256 Quantatizing levels Sample Points RTO Ideal mv mv < ı Higher ENOB => lower quantization error and higher SNR Offset Error Gain Error Nonlinearity Error Aperture Uncertainty And Random Noise Better accuracy 8 bits Effective Number of Bits! 31/05/2013 EMI debug using R&S RTO 11

12 #1 High Signal Fidelity: Convincing Accuracy Multiple ADCs ı 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 Interleaving distortions In Frequency Domain Signal Interleaving Artifact Spurious Frequency Phase Errors 31/05/2013 EMI debug using R&S RTO 12

13 #1 High Signal Fidelity: Convincing Accuracy Input Sensitivity ı Do you expect your scope to perform with its Full Bandwidth Specification at all time? Input Coupling Amplifiers Position BNC Input Channel ADC Vertical Input Sensitive Range Use with x10 Active Probe R&S RTO102x Offset 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 31/05/2013 EMI debug using R&S RTO 13

15 #2 Market Leading Acquisition Rate ı Sees up to 20x more than traditional oscilloscopes ı => Detect and also analyze rare signal 20x faster 31/05/2013 EMI debug using R&S RTO 15

16 #2 Market Leading Acquisition Rate R&S Enabler: RTC ASIC ı An Acquisition ASIC with high integration level (14 million gates) and massive parallel high-speed paths 20x parallel: acquisition block ADC 8 bit, 10 Gbps 20x 8 bit, 500 Mbps 160x 500 Mbps Memory Acquisition Display 4x parallel: post-processing block Post-Processing Measurement, etc. 4x 8 bit Memory R&S RTC ASIC 90nm technology 14 M gates ASIC 31/05/2013 EMI debug using R&S RTO 16

17 #2 Market Leading Acquisition Rate Data Decimation & Waveform Arithmetics ı Differentiated analysis with up to 3 simultaneous waveforms per channel Original Waveform 1 Channel Envelope Waveform Hi-Res Waveform 31/05/2013 EMI debug using R&S RTO 17

18 #2 Market Leading Acquisition Rate Hardware Accelerated Analysis ı Most of analysis functions implemented in RTC ASIC & FPGA Acquisition rate remains high even during complicated signal analysis Histogram Testing Mask Testing 31/05/2013 EMI debug using R&S RTO 18

19 #2 Market Leading Acquisition Rate Hardware Accelerated Analysis Fast FFT l FFT based spectrum analysis: powerful & user-friendly l Mask testing on FFT and correlate with Time Domain HW overlapping FFT implementation => Very responsive and intensity modulated color display. Mask violation -> Stop Acquisition 31/05/2013 EMI debug using R&S RTO 19

21 #3 Unique Digital Trigger System Challenges of Analog Triggering ı 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 ı Comparison of Digital and Analog triggering architecture Traditional Innovative Digital Trigger 31/05/2013 EMI debug using R&S RTO 21

22 #3 Unique Digital Trigger System Challenges of Analog Triggering ı 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 31/05/2013 EMI debug using R&S RTO 22

23 #3 Unique Digital Trigger System R&S RTO Implementation Benefits ı Digital Triggering in Realtime is unique to RTO: Real time, no DSP post correction! ı 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! 31/05/2013 EMI debug using R&S RTO 23

25 #4 Memory Implementation Speciality R&S RTO Unique History View Mode ı Each waveform acquisition: is being stored in R&S RTO memory automatically can be playback anytime whenever is needed ı Note: RTO has the shortest Blind Time! 31/05/2013 EMI debug using R&S RTO 25

27 #5 Intuitive User Interface ı 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 31/05/2013 EMI debug using R&S RTO 27

28 FFT as Basis for EMI Debugging with Oscilloscopes Conventional FFT Implementation on a Scope Time Domain Dt = 1/F s F max = F s /2 Frequency Domain x(t) S(f) S(f) t Data acquisition Windowing FFT f 1 f 2 f Zoom (f 1 f 2 ) f 1 f 2 Display f Record length 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 31/05/2013 EMI debug using R&S RTO 28

29 FFT on the RTO Spectrum Analyzer Use Model ı Use model: Frequency domain controls time domain Time domain parameters (record-length / sampling Time Domain x(t) Zoom happens here before the FFT! 500 MHz center, 10 MHz span: Fs = 1 GS/s vs 20 MS/s F s =2B Data acquisition t HW Zoom (DDC) NCO LP rate) automatically changed as necessary ı 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 Decimation sampling frequency Windowing FFT S(f) B=f 2 -f 1 f 1 f 2 Display f Frequency Domain Record length T Df = 1/T 31/05/2013 EMI debug using R&S RTO 29

30 What if we combine time and frequency domain? Overlap FFT comes into play Record length 10GS/s 18.96ns/div 5 us/div ksamples FFT 1 FFT 2 FFT N Max frame count limit N = N max Frame coverage up to here ~440 1 FFTs (persistance disabled) 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! 31/05/2013 EMI debug using R&S RTO 30

31 Gated FFT in the RTO Practical Time-Frequency Analysis Gated FFT: 50% overlap (default setting) One complete Time-Domain capture Key Feature for EMI Debug! 31/05/2013 EMI debug using R&S RTO 31

32 FFT Further Settings, Further Features Max-Hold*, Average, RMS 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 Record length > 1 MS *Note: Envelope = Max Hold 31/05/2013 EMI debug using R&S RTO 32

33 What Accessory do we have? Near-Field Probes R&S HZ-15 E- and H-field Hameg HZ530 E- and H-field Hameg HZ540/550 E- and H-field EUR 1.730,- Small size No battery needed Probe single circuit lines 30 MHz 1 GHz Can be used down to 100 khz 100 khz 1 GHz 1 MHz 3 GHz EUR 788,- EUR 1.428,- / 1.848,- Note: No power supply included LISN R&S ENV216 Hameg HM EUR 2-4k EUR 1.038,- Note: You need an isolation transformer for operating the LISN 31/05/2013 EMI debug using R&S RTO 33

34 EMI Debugging: Equipment R&S RTO Near-field sniffer Probes R&S HZ-15 E- and H-field 30 MHz 1 GHz Can be used down to 100 khz Optional: R&S HZ-16 Preamplifier 31/05/2013 EMI debug using R&S RTO 34

35 EMI Debugging: Equipment R&S RTO Near-field sniffer Probes R&S HZ-15 E- and H-field 30 MHz 1 GHz Can be used down to 100 khz Optional: R&S HZ-16 Preamplifier 31/05/2013 EMI debug using R&S RTO 35

36 Frequency Analysis Debugging EMI Test & Analysis Electric field Probe Magnetic field Probe l Analyzing EMI Faults: - Detecting possible signal problem due to EMI and sniff out the EMI source on the DUT l Locating EMI weak points: - Injecting EMI to detect possible signal faults to identify weaker DUT location 31/05/2013 EMI debug using R&S RTO 36

37 EMI Debug with Near-Field Probes Important Settings Parameter Record length Vertical settings Color table & persistance Max. Frame Count Signal zoom & FFT gating Description Ensure that you capture enough (>= 500 ksamples) 1 5 mv/div, 50 W Easily detect and distinquish CW signals and burst Take care that you analyze the right part of the time signal Easily isolate spurious spectral components in time domain 31/05/2013 EMI debug using R&S RTO 37

38 EMI voltage test: Basic test setup >200 cm reference ground > EUT AN test receiver 4 0 cm 30 to 40 cm 8 0 cm > 8 0 cm wooden table 31/05/2013 EMI debug using R&S RTO 38

39 Precompliance Measurements with a Scope??? Conducted Emission using LISN 9 khz 30 MHz EN55015Q FSV trace 1 = Max hold / Pos Peak FSV trace 2 = Clear Write / Auto Peak RTO FFT1 = Normal mode RTO FFT2 = Envelope mode 31/05/2013 EMI debug using R&S RTO 39

40 Precompliance Measurements with a Scope??? Conducted Emission using LISN 9 khz 1 MHz EN55015Q FSV trace 1 = Max hold / Pos Peak FSV trace 2 = Clear Write / Auto Peak RTO FFT1 = Normal mode RTO FFT2 = Envelope mode 31/05/2013 EMI debug using R&S RTO 40

41 FAQs and Answers Sensitivity ı 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 ı How to show on the RTO using the FFT Note: Vertical Settings are 1mV/div, 50 W But: A. RTO dynamic range very limited compared to EMI receivers B. No preselection in RTO! Sampling rate>=2xbw of the scope! Otherwise aliasing will increase noise! 1 Measured 2 Datasheet value 31/05/2013 EMI debug using R&S RTO 41

42 FAQs and Answers Noise Figure ı 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 dbm = 16 db 31/05/2013 EMI debug using R&S RTO 42

43 FAQs and Answers What about ı Limit Lines? Use the mask tool Upper for limit line usage Mask definition in units of FFT Upper region mask acting as limit line Stop-on mask violation setting is very useful! ı 6 db EMI filter? Not critical for precompliance, will change results only slightly. 31/05/2013 EMI debug using R&S RTO 43

44 Use Cases 31/05/2013 EMI debug using R&S RTO 44

45 EMI Debugging with Near-Field Probes Use Cases ı A) Debugging problems that occurred during compliance test Noise from power supply Unknown broadband noise peak CW Emission Identifying the location of the emission (down to signal paths) Understanding signal behaviour to identify the source ı B) Benchmarking EMI mitigation measures Problem in compliance test Check if shielding etc enough 31/05/2013 EMI debug using R&S RTO 45

46 EMI Source Identification Advanced debugging Using the RTO for the far-field EMI Receiver, Spectrum Analyzer Oscilloscope Source: Weifeng Pai, David Pommerenke: EMI Failure Analysis Techniques: II: Joint Time-Frequency Analysis 31/05/2013 EMI debug using R&S RTO 46

47 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 31/05/2013 EMI debug using R&S RTO 47

48 EMI Debug Customer Groups ı EMC test house engineers General EMI Debugging Far-field and near-field measurement Pulse calibration (ESD, EFT, Burst) ı In-house EMC labs See above ı Design engineers A) After failed compliance B) Pre-Compliance Conducted emissions with LISN Radiated emissions when experienced enough 31/05/2013 EMI debug using R&S RTO 48

49 Summary USPs of the RTO for EMI Debugging ı Sensitivity similar to EMI receivers ı Capture intermittent events with stop-on-mask-violation in frequency domain But, also time-domain trigger can help ı Analyze in frequency domain after capturing (changing RBW etc) ı Time-frequency correlation analysis (FFT gating) Discover cause of emission in time signal ı Flexible and easy-to-use FFT Use it like a spectrum analyzer 31/05/2013 EMI debug using R&S RTO 49

50 Thank You! 31/05/2013 EMI debug using R&S RTO 50