Tektronix Software Performs Serial Data Link Analysis

The latest high-speed serial technologies are at the core of the computer, consumer electronics, and communications industry designs and require test equipment capable of higher performance and more extensive analysis. The new 80SJNB Advanced software includes feed-forward and decision feedback equalization (FFE and DFE) for a virtual view of the signal as it appears at the comparator inside the receiver. Emulation of the interconnect channel enables testing the transmitter performance against multiple interconnects. Support for fixture de-embedding facilitates virtual probing at inaccessible points. The complete SDLA offering provides the fundamental measurements needed to validate compliance of high-speed serial standards such as 10 GbE Ethernet, PCI-Express and SATA, enabling the development of higher performance products for the new digital world.

“As serial data speeds increase, loss and distortion caused by the channel must be equalized in the receiver for the signal to be recognizable,” said Ian Valentine, General Manager, Electrical Optical Product Line, Tektronix. “The DSA8200 measurement system already provides channel characterization with TDR/TDT and S-Parameter support. The new 80SJNB Advanced software with complete equalization and channel emulation provides the most advanced serial data link analysis test tools in the industry. Using a SDLA measurement system from Tektronix, an entire design from the transmitter to the receiver comparator can be characterized and tested for compliance.”

“Due to the higher speed of the latest serial interface standards under development, test fixturing and small changes in the channel can cause significant changes to the signal characteristics,” said Eric Kvamme, Principal Engineer, LSI Logic. “With their ability to de-embed fixtures, emulate channels, and model equalization right on the high speed scope, the new Tektronix SDLA tools including the DSA8200 with 80SJNB Advanced software help LSI to more quickly characterize our serial products. This will enable us to evaluate their performance under additional scenarios to provide a more robust solution to our customers.”

Equalization is a broad term for several techniques of manipulating the signal shape in order to overcome frequency dependent loss of the channel. This loss changes the shape of the NRZ data signal at the receiver from the desired square-wave to severely distorted, closed eye waveform. 80SJNB Advanced provides the important equalization methods of FFE and DFE on the receiver side, and supports generation and measurement of pre-emphasis and de-emphasis on the transmitter side.

Another capability of the software is channel emulation, providing customers a push-button way to see the waveform impairments due to channel (interconnect) transmission loss. Through channel emulation engineers are able to acquire the signal at the transmitter output, and distort it by an (emulated) channel – be it a backplane, connector, anything that can be described with TDR/TDT or with S-Parameters – and verify the performance at the channel end, without waiting for the physical hardware’s availability. Final analysis is performed using 80SJNB Advanced jitter and noise decomposition and BER eye diagrams.

With 80SJNB Advanced, design engineers gain the ability to compare different transmitter-to-channel-to-equalizer combinations, resulting in improved design and verification. The waveform and the eye diagram at any point are not only viewable, but also available for a complete Jitter, Noise and BER analysis.

Acquisition and advanced analysis of complex signals is increasingly needed on transmitters with spread spectrum clocks (SSC). 80SJNB software and the DSA8200 now provide engineers a sampling oscilloscope with an unmatched ability to perform SSC acquisitions and SSC jitter analysis. SSC is widely used in desktop and laptop PCs and is incorporated into standards including SATA and PCI-Express.