Technologies

Simple Active EQ Solutions to Signal Integrity
Most signal integrity issues can be addressed by a straightforward active equalization approach. Active equalization can remove up to 80% of the jitter in a typical application.

Active equalization (EQ), available in Vitesse crosspoint and transceiver products, integrates passive equalizers and amplification techniques. The resulting circuits can nearly erase the effects of lossy lines. Active equalizers can be designed to produce a nearly flat response across a wide range of jitter conditions.

Vitesse Input EQ or Output Pre-emphasis settings allows for optimizations at either end of a communication link. Furthermore, Vitesse offers simple, cost effective multi-channel equalizers, which require minimal board space and are easy to integrate in existing board designs.

The jitter-leveling capability of Vitesse's proven, active EQ equalization circuit technology, can be found in several products including signal conditioners, transceivers and crosspoints. Crosspoints include switching capability to support redundancy, protection switching, and re-ordering system functions.

Using Clock Data Recovery (CDR) for a Complete Signal Integrity Solution
While degradation in copper-based interconnect systems consists mainly of inter-symbol interference (deterministic jitter), there are two classes of degradation that may require further countermeasures: crosstalk and random jitter. In designs with poor isolation, coupling from adjacent signals will add jitter that is uncorrelated to the signal being recovered. In many optoelectronic systems, such as parallel optical ribbons, the optical-electrical conversions add random noise that is independent of the data content of the signal. Removing these types of jitter requires that the signal be re-sampled using a recovered clock, and this makes the case for an architecture that includes clock and data recovery.

In cases where the signal degradation is dominated by random effects, a solution with clock and data recovery is indicated. The most typical example of this would be an optical link that includes both deterministic jitter from PCB traces, and random jitter components from the optics portion of the signal path.

Technologies such as Vitesse's VSC32xx family of CDR crosspoints include the crosspoint switch functionality and EQ performance and add per-channel CDR capability. By integrating SerDes, CDR and EQ technologies on chip, OEMs are provided with a simple, comprehensive tool needed to build communication platforms with optimal system performance. Real-world results show the combined EQ and CDR technology eliminates both deterministic and random jitter over backplane channels that are up to 1m long and low cost cables as long as 10m. The VSC32xx devices yield a constant jitter of less than 80 ps over data rates ranging from 155 Mbps to 4.25 Gbps.

Signal Integrity is a major issue for system designers developing new communication systems or upgrading bandwidth capacity for systems that are already deployed. The good news is that Vitesse offers simple, proven and cost-effective solutions to address this complex problem.

Introducing VScope™
Vitesse continues to deliver new Signal Integrity solutions with the introduction of VScope™. With VScope, engineers and even system operators can scan received data from within the IC itself in a manner similar to oscilloscopes and bit error rate detectors. Offered in clock and data recovery products from Vitesse, VScope can operate on any channel of live data, enabling unique capabilities for testing and system monitoring. For more information on this "Oscilloscope on a Chip" technology visit: www.vitesse.com/vscope .