Sassan Tabatabaei, Freddy Ben-Zeev and Michael Lee Jitter Generation and Measurement for Test of Multi-gigabit Serial Interconnects Sassan Tabatabaei, Freddy Ben-Zeev and Michael Lee

Purpose RJ, DDJ, and PJ injection for receiver test Use delay line modulation Programmable DDJ Jitter measurement methodology with continuous TIA (CTIA) Markerless measurement Objectives: To inject jitter in data streams for jitter measurement verification and receiver testing with: Programmable RJ Programmable high and low frequency PJ Programmable DDJ Discuss continuous time interval analyzers and how they can measure jitter without any marker signal ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Outline Jitter injection issues Programmable jitter injection Continuous time interval analyzer (CTIA) Markerless and fast RJ/DDJ measurement methodologies ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Typical setup (e.g., XAUI) Jitter Injection Typical setup (e.g., XAUI) Typical jitter injection setup includes: Pj injection through PM/FM modulation of RJ generators (limited in frequency and range) RJ through amplitude superposition (sensitive to rise/fall time and glitches) DDJ: fixed application-specific filters ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Jitter Injection Limited PJ frequency range Large RJ may cause spurious edges DDJ programmability very limited Requires filter tuning Typically not portable across applications with different bit rates ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Jitter Injection Programmable setup NEW Info Proposed method. Use delay line phase modulation in a phase-locked system NEW Info ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

DDJ Injection DDJ injection setup ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Traditional Time Interval Analyzer (TIA) Operation Principles Traditional TIA architectures ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Traditional Time Interval Analyzer (TIA) Operation Principles Traditional TIA architectures with marker signal ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Continuous Time Interval Analyzer (CTIA) Operation Principles Continuous TIA operation Tracking edge timing relative to a common reference continuously ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Continuous Time Interval Analyzer (CTIA) Operation Principles CTIA does not require any marker! TO demonstrate examples in RJ/DDJ measurement methods. ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Jitter Measurement Definitions Random jitter (RJ) Uncorrelated to Known sources Gaussian distribution Data-dependent jitter (DDJ) Inter-symbol interference Duty-cycle distortion Reflections Definitions Objectives: To inject jitter in data streams for jitter measurement verification and receiver testing with: Programmable RJ Programmable high and low frequency PJ Programmable DDJ Discuss continuous time interval analyzers and how they can measure jitter without any marker signal ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Jitter Measurement Definitions Time Interval Error (TIE) function: Ideal signal Real signal ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

RJ Measurement Data signal with a repeating pattern (K28.5 in this example) ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

RJ Measurement TIE measurement for the same edge of the pattern ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

RJ Measurement Sampling the same pattern edge: DDJ deconvolution Uniform sampling of edge deviation sequence. Good for FFT. ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

RJ Measurement TIE TIE FFT Time (s) Normalized frequency 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 -100 -50 50 100 Time (s) TIE sequence (ps) TIE 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 10 -4 -2 2 Normalized frequency Scaled FFT (ps) TIE FFT FFT deconvolves PJ ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

RJ Measurement Frequency domain deconvolution Insensitive to PJ and DDJ Predictable Repeatability 3% for 8192 samples No external marker required ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

DDJ Measurement DDJ: set event counter to walk over pattern edges multiple times (virtual marker!). ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

DDJ Measurement Histogram for each pattern edge Edge 5 Edge 4 Edge 2 -40 40 80 120 20 60 100 TIE (ps) Bin population Histogram for each pattern edge Edge 1 Edge 2 Edge 3 Edge 4 Edge 5 Separate TIE for pattern edges. Measure DDJ. ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

DDJ Measurement Time domain deconvolution Per-edge time shift measurement Insensitive to RJ and PJ (averaging) No external marker required ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Example: Sinusoidal DDJ DDJ Injection Example: Sinusoidal DDJ 15 CTIA (GT 4000) Scope (86100C) 10 5 Edge shift (ps) Example of DDJ injection performance. -5 -10 20 40 60 80 100 120 Transition bit number ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Measurement Results (RJ) Accuracy 20 22 24 26 28 30 32 3 4 6 8 10 RJ (ps) CTIA TDS7404 Linear fit -0.5 0.5 D Noise generator attenuation (db) RJ is accurate within 0.5ps. ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Measurement Results (RJ) Immunity to DDJ 2.5Gbps, PRBS7 pattern 20 25 30 35 40 5.4 5.5 5.6 5.7 5.8 RJ (ps) Injected DDJ (ps) RJ is immune (insensitive) to variations of DDJ. Maintain accuracy for different jitter profiles. ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Measurement Results (DDJ) Accuracy 50 45 40 PRBS7 35 30 Measured peak-to-peak DDJ (ps) K28.5 25 DDJ accuracy (within 3ps) CTIA 20 ET-DSO 15 10 20 40 60 80 100 120 140 160 AWG amplitude (mV) ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Measurement Results (DDJ) Immunity to RJ and PJ 2 4 6 8 10 12 32 33 34 35 Measured peak-to-peak DDJ (ps) Injected RMS RJ (ps) 50 100 30 31 32 33 34 Injected PJ (ps) Measured peak-to-peak DDJ (ps) DDJ injection and measurements immune to RJ and PJ. ITC 2004 Jitter Models & Measurement for High-Speed Interconnects

Conclusions Delay line modulation with locked AWG provide flexible and programmable jitter injection method. No need for application-specific DDJ filters CTIA: markerless jitter separation Virtual marker Accurate Fast: No marker generation time Compact data volume Completely programmable jitter injection method including DDJ introduced. CTIA perform jitter decomposition without any marker signal. ITC 2004 Jitter Models & Measurement for High-Speed Interconnects