400G PAM4 Testing
Overcoming 400G measurement challenges
The rapid worldwide growth in cloud computing is driving massive demand for high-performance datacenter infrastructure. To keep pace with this relentless demand, developers are transitioning to 400G technologies enabling smaller, faster, lower cost-per-bit solutions.
There are several core technologies that are enabling 400G, including the use of higher order modulation and higher data rates up to 56 GBaud. This new modulation scheme provides four-level pulse amplitude modulation (PAM4), which transmits two bits per symbol, doubling the data rate compared to conventional NRZ.
PAM4 signals, having a lower signal-to-noise ratio and 1/3 of the amplitude of equivalent NRZ, require more advanced tools and features for successful validation.
Accelerate 400G product development
Developing 400G products is challenging. PAM4 signals require more sophisticated tools and features in order to evaluate them successfully. The DPO7OE series optical probe with a DPO70000 real-time scope provides superior features, trigger and debug capabilities to effectively troubleshoot and measure PAM4 signals up to 56 GBaud.
Tektronix Real-time solutions give you the ability to efficiently validate your technology advances and rapidly debug and validate 400G technology complementing the low-noise of a sampling oscilloscope.
Validate faster and increase yield
One of the greatest challenges is keeping test cost per device as low as possible while meeting required specifications. With PAM4 signals increasing the number of tests needed to conduct versus NRZ signals by a factor greater than 10, solutions providing measurements quickly for optimized tuning, with the lowest noise to maximize production yields are required.
The Tektronix sampling solutions include the DSA8300 and the 80C20/21 optical module to provide the highest bandwidth, highest sensitivity, and shortest test time when testing up to 56 GBaud. This solution enables you to effectively balance performance and testing costs.
Optical Bandwidth Requirements for NRZ and PAM4 Signaling
Until recently, both optical and electrical bandwidths produced similar results but this is no longer the case with the recent IEEE spec change. This paper clarifies these terms, mathematically shows how they are related, and provides the basis to understand and confidently calculate optical and electrical bandwidth for an optical channel.
OFC 2017 - PAM4 Debug and Analysis with Real Time Oscilloscope
This demonstration video highlights the benefits of using the DPO70000SX real time oscilloscope-based system for 400G optical/electrical PAM4 debug and analysis.
Optical Probing and Measurements with a Real-time Oscilloscope
Prepare for the new challenges in optical networking. During this webinar, experts will address critical design issues posed by integrating optical PAM4 capabilities into optical networking components or systems utilizing the capabilities of a real-time oscilloscope.
PAM4 Real-Time Scope Software
- Comprehensive set of electrical and optical measurements that cover IEEE and OIF-CEI standards as well as jitter and eye measurements for PAM4
- Single integrated application with auto configuration of several signal parameters enables ease of use
- Detect and navigate to individual symbol errors with annotations
- Comprehensive plots and reports for visualizing and analyzing the measurements results
DPO70000SX Real-Time Scope
Simplify the complex 400G test setup with the most accurate capture of high-speed signal behavior to verify, validate and characterize your next generation designs.
- 23, 33, 50 and 70 GHz Bandwidth models available
- Simple, extensive PAM4 analysis - without needing external CR
- Powerful debugging tools to quickly uncover/fix design challenges
- Debugging of complex Link Training sequences
- Characterize PAM4 and NRZ signals
- Both optical and electrical measurements available
NEW! Optical Probe for Real-Time Scopes
Easily troubleshoot with powerful debug capabilities: software clock recovery for PAM4 and NRZ, triggering, error detection, and capture time correlated or contiguous acquisition of a signal.
- For use with DPO/MSO70000C/DX/SX Real-time scopes
- Wavelength Response from 1200m-1650nm
- High-bandwidth DC up to 59 GHz
- Optical Noise 10 µW (ATI)
- NRZ (PAM2) and PAM4 Reference Receiver 56 Gbaud
- Use as conventional O/E with flat response filter for general laser signal acquisition up 59 GHz
PAM4 Sampling Scope Software
Fully featured 400G PAM4 measurements supporting emerging OIF-CEI and IEEE standards.
Jitter, noise, and BER analysis of high-speed PAM4 and PAM2 NRZ
PAM4 400G TX Optical Compliance SW
(IEEE802.3bs and IEEE802.3cd)
- Analysis of PAM4 signals with comprehensive jitter, noise and BER analysis for each individual PAM eye for data rates from <1 Gb/s to 60 Gb/s provides insight into precise causes of eye closure
- Separation of both jitter and noise provides highly accurate extrapolation of BER and eye contour
- CTLE/FFE/DFE equalization of the signal opens the eye diagram for measurements - view the signal the way it is viewed by the receiver comparator
- Optical transmitter measurements for IEEE 802.3bs and IEEE 802.3cd specifications
- Validation of 50GBASE-FR/LR, 100GBASE-DR, 200GBASE-DR4/LR4/FR4 and 400GBASE-LR8/FR8/DR4 standards
DSA8300 Sampling Scope
Well-suited for detailed characterization of PAM4 and Transmitter Distortion Eye Closure Quaternary (TDECQ) based measurements. Supports electrical and optical based signals for R&D and manufacturing test.
- Low time base jitter of <100 fs on up to 6 channels with 82A04B phase reference module
- Optical bandwidths to >80 GHz
- Electrical bandwidths to >70 GHz
- Over 120 automated measurements for NRZ, RZ, and PAM4
- Complex jitter/noise/BER/SER analysis (80SJNB), support for complex measurements TDECQ, SNDR
NEW! Optical Modules for Sampling Scope
Increase production capacity and improve yield for current 400G designs moving into production with industry's highest mask test sensitivity and lowest optical noise.
- For use with DSA8300 Sampling Scope
- Wavelength range of 1200nm-1650nm
- Unfiltered optical bandwidth 53 GHz
- Typical mask test sensitivity -10 dBm
- RMS optical noise (typical at 1310 nm) is 9 µW (@ 37 GHz)
|Optical Bandwidth Requirements for NRZ and PAM4 Signaling|
Until recently, both optical and electrical bandwidth produced similar results but this is no longer the case with the recent IEEE spec change. This paper clarifies these terms, mathematically shows how they are related, and provides the basis to understand and confidently calculate optical and electrical bandwidth for an optical channel.