Deailed comparison of dynamic range beween a vecor nework analyzer and sampling oscilloscope based ime domain reflecomeer by normalizing measuremen ime Sho Okuyama
Technology Trends & Issues in High-Speed Digial Sysems Higher Daa Rae Smaller Componen Spacing Lower Volage Consumpion Waveform Disorion Ideal waveform Crossalk Noise Sray capacior Lower Signal Level Disored waveform Elecromagneic wave Greaer accuracy in measuremen is essenial o reduce bi error
Relaionship Beween Time and Frequency Domain Hisorically, TDR oscilloscope and VNA have been used for passive device characerizaion TDR oscilloscope Sep simulus Sep response DUT 0 0 Derivaion Inegraion Derivaion Inegraion Impulse simulus Impulse response DUT 0 0 Sine wave sweep VNA Frequency response DUT f 0 0 Time domain response and frequency domain response are converible based on Fourier ransformaion. f
Accuracy in Frequency Domain VNA can make measuremens accuraely in frequency domain TDR oscilloscope VNA 60 50 40 30 160 140 120 100 20 80 The dynamic range of a TDR oscilloscope is inversely proporional o frequency The dynamic range of a VNA is uniform across frequency. Wha abou accuracy of VNA and TDR oscilloscope in ime domain?
Facors of Measuremen Accuracy The SN raio direcly deermines he measuremen accuracy. Measuremen accuracy depends on SN raio and measuremen speed. A faser insrumen can average more races o reduce random noise. Single 4 averaging 16 averaging We mus compare hese insrumens conrolling for ime
Comparing Measuremen Accuracy of VNA and TDR Oscilloscope Comparison Procedure Single measuremen is defined as reconsrucing one race in ime domain wihou averaging. 1.Comparing SN raio for a single measuremen. 2.Comparing measuremen ime for a single measuremen 3.Comparing he SN raio over he same measuremen ime
Comparing SN Raio for a Single Measuremen Assumpions o simplify he discussion Two insrumens have he same cuoff frequency (fc). The noise is uniform up o he cuoff frequency, which is whie noise. The magniude of simulus and incoming noise are equivalen on boh insrumens. TDR oscilloscope VNA b Noise b a Simulus fc f a fc f b a The magniude of simulus and noise remain unchanged. fc f IFBW/fc b a IFBW The bandpass filer dramaically reduces noise Bandpass filer f
Comparing SN Raio for a Single Measuremen Assumpions o simplify he discussion Two insrumens have he same cuoff frequency (fc). The noise is uniform up o he cuoff frequency, which is whie noise. The magniude of simulus and incoming noise are equivalen on boh insrumens. TDR oscilloscope VNA b Noise SN raio on each daa poin is improved a Simulus fc f f b IFBW/fc b a The magniude of simulus and noise remain unchanged. fc f a SN raio wih respec o ime is improved by he same facor. The VNA demonsraes a beer SN raio by he facor of fc/ifbw.
Comparing Measuremen Time for a Single Measuremen TDR oscilloscope VNA Equivalen sampling rae : Se Number of daa poins: M = T Se Equivalen waveform T Frequency response f Number of daa poins: M 1/IFBW 1/IFBW 1/IFBW 1s poin 2nd poin Mh poin Se Sp T = M Sp Physical sampling rae: Sp M/IFBW IF band widh: IFBW Difference of measuremen ime is deermined by Sp and IFBW.
Comparing Measuremen Accuracy of VNA and TDR Oscilloscope Comparison Procedure 1.Comparing SN raio for a single measuremen VNAs have beer SN raio by he facor of fc/ifbw. When fc=20 GHz and IFBW=70 khz, he SN raio of VNA is 4,472 imes beer han he TDR oscilloscope in erms of volage. 2. Comparing measuremen ime for a single measuremen Raio of measuremen ime beween wo insrumens is Sp/IFBW. When Sp=150 ks/s and IFBW=70 khz, he measuremen ime of he TDR oscilloscope is 150 imes shorer han ha of he VNA. 3.Comparing SN raio for same measuremen ime Even afer equalizing measuremen ime, he SN raio of VNA is sill beer han TDR oscilloscope by he facor of fc/sp. When fc=20 GHz and Sp=150 ks/s, he SN raio of VNA is 365 imes beer han TDR oscilloscope in erms of volage. Cuoff frequency : fc Equivalen sampling rae : Se Physical sampling rae: Sp
Agilen E5071C ENA Nework Analyzer Opion TDR The ENA Opion TDR allows he ENA Nework Analyzer o perform ime domain analysis. TDR measuremens can be made in he same manner as radiional TDR oscilloscopes. ENA Nework Analyzer
Empirical Comparison Using he ENA Opion TDR The number of daa poins was se o 1000 on boh insrumens. IFBW was se o 1 khz on he ENA Opion TDR. RMS Noise Measuremen Time wihou averaging ENA Opion TDR 1.65 μv @0 sec 1066 ms TDR oscilloscope 591 μv 22 ms The TDR oscilloscope averages 50 races o equalize measuremen ime. Bu ENA Opion TDR TDR oscilloscope 1 mv 1 mv ENA Opion TDR provides a much smooher race wihou averaging.
Empirical Comparison Using he ENA Opion TDR The number of daa poins was se o 1000 on boh insrumens. IFBW was se o 1 khz on he ENA Opion TDR. RMS Noise Measuremen Time wihou averaging ENA Opion TDR 1.65 μv @0 sec 1066 ms TDR oscilloscope 591 μv 22 ms In order o achieve a noise level comparable o he ENA Opion TDR, he TDR oscilloscope mus perform over 100,000 averages. RMS Noise Measuremen Time wihou averaging ENA OpionTDR 1.65 μv @0 sec 1066 ms TDR oscilloscope 1.65 μv? 2,822 sec? Impracical value for ordinary use
Comparison in Pracical Measuremen DUT is a single-ended race wih a small sab
Comparison in Pracical Measuremen DUT is a single-ended race wih a small sab ENA Opion TDR TDR Oscilloscopes 1 ohm/div 1 ohm/div ENA Opion TDR deecs a disconinuiy corresponding o he small sab, whereas TDR oscilloscope doesn.
Comparison in Pracical Measuremen DUT is a single-ended race wih a small sab ENA Opion TDR TDR Oscilloscopes 1 ohm/div Averaging 1 ohm/div Averaging gives accurae measuremen BUT
Comparison in Pracical Measuremen DUT is a single-ended race wih a small sab ENA Opion TDR TDR Oscilloscopes 1 ohm/div Averaging 1 ohm/div Real-Time Analysis Takes a long ime o updae
Summary We se ou o compare he SN raio of VNA and he TDR oscilloscope Mehod: In order o make a fair comparison, we conrolled for ime Empirical daa proves ENA Opion TDR provides higher SN raio even afer equalizing measuremen ime. Please come o Agilen booh for more deail. Thank you!
Appendix: Measuremen Correlaion Comparison of DCA-J 86100C TDR oscilloscope and ENA Opion TDR. Measuremens are made using he same differenial race. USB3.0 cable impedance SATA cable eye diagram TDR oscilloscope ENA opion TDR Measuremen resuls from ENA Opion TDR are highly comparable o TDR oscilloscope.