The DS38EP100 power-saver equalizer can equalize 40 inches of FR-4 printed circuit board (PCB) at a data transmission rate of 3.125 Gbits/s -- twice the reach of other passive equalizers. Compared to active equalizers, National’s DS38EP100 and DS80EP100 are more versatile. They require no power or ground routing and they accept any high-speed differential signal technology, including current-mode logic (CML), low-voltage differential signaling (LVDS) and low-voltage positive emitter coupled logic (LVPECL). Additionally, they are bi-directional, offering the same equalization gain in either direction.

 

The DS38EP100 andDS80EP100 are well-suited for many applications such as routers, storage subsystems and wireless base stations. They are supplied in a tiny 6-pin LLP package for use in space- and layout-constrained systems, such as cables or connectors in medical, security and industrial imaging systems. The DS38EP100 operates from 1 Gbits/s to 5 Gbits/s, while the DS80EP100 operates from 5 Gbits/s to 10 Gbits/s. They address a variety of systems using high-definition multimedia interface (HDMI) or digital visual interface (DVI) interface standards, as well as systems using a PCI Express or XAUI interface.

 

With no power or ground required, system designers can easily place these power-saver equalizers in cables, connectors or backplanes, and they can add them to a board with a minimum of layout changes. They can also cascade these devices with an active equalizer or limiting amplifier to further extend FR-4 and cable transmission links.

 

In addition to doubling the reach of FR-4, the DS38EP100 can equalize up to five meters of cost-effective 28 American Wiring Gauge (AWG) HDMI cable at a data rate of 3.4 Gbits/s. It features 7 dB of maximum boost and its input and output impedance is 100 Ohms. The DS38EP100 supports all data coding techniques such as 8b/10b and scrambled signals. The DS80EP100 offers similar technical features and at 10 Gbits/s can equalize 20 inches of FR-4 and five meters of 26 AWG cable. Both equalizers operate over the full -40 degrees C to 85 degrees C temperature range.

 

The DS38EP100 and DS80EP100 are the latest additions to National’s growing family of signal-conditioning equalizers, which include the DS16EV5110 video cable equalizer, DS25BR110 LVDS equalizer, DS40MB200dual mux-buffer, and DS15BA101 and DS15EA101 cable extender chipset.

 

 

 

Since they are such clever little devices (and the fact that most players in the connectivity market space seem to have taken the summer off), I’ve made an exception to EN-Genius' unofficial policy of not reviewing the same company’s products in two subsequent issues to give you a quick peek at National’s latest addition to its passive equalizer series. According to the folks at National who briefed me, their fixed EQ curve is based on a composite model of the common environments they are expected to be used in, namely FR-4 PCB traces in motherboards and backplanes, PCIe/IB cables, and HDMI cables. The passive networks are non-adjustable but provide enough bi-directional equalization for PCB traces as long as 40 inches at slow speeds (2.5 - 5 Gbit/s) and up to 20 inches at higher speeds.

 

National’s informative release covers most of what I’d normally talk about here but it’s interesting to re-emphasize that since these devices are passive, they are I/O agnostic, allowing them to be used for nearly any differential interface technology including LVDS, CML, PECL, or your favorite proprietary signaling scheme. Designers will also appreciate the fact that these equalizers eliminate the need for ac-coupling when bridging between drive technologies.

 

One of the more interesting applications the tiny packages make possible is embedding in cables or connectors. I think that backplane connectors sporting embedded equalization components could save lots of space and design hassles in today’s high-density environments. In applications where the signal budget is sufficient, self-equalizing passive cables could be a very cost-effective alternative to the active cabling that’s been recently introduced by Quellan/Gore, Zarlink, and other sources. National has been touting their equalizers for cables carrying InfiniBand (up to 4x), PCI Express but they have also discovered there is significant interest in HDMI for high-end consumer video products. They say that adding equalization to an HDMI cable allows runs of 20 feet or more with a very usable signal at the other end. While mostly intended for high-end consumer applications, HDMI video connections are also beginning to be popular in medical equipment that uses high-definition displays.

 

Like the rest of their brethren, DS38EP100 and DS80EP100 use National 8B+ bipolar process to build the array of integrated passives. When I asked the National briefing team why they went with the more expensive process instead of bulk CMOS, they offered vague explanations that it provided better linearity, matching and speed. I’ll also speculate that they chose it because of the better substrate isolation and thicker dielectric materials process offers. Although National would not comment, a thicker dielectric would explain the device’s ability to handle signal levels up to 4 V and might have something to do with its relatively clean, sharp frequency response curve and low insertion losses.

 

My briefers at National were unable (or unwilling) to tell me whether their bipolar process uses standard oxide or some of the new high-k materials that have become so popular with high-performance CMOS processes but, whatever they use, the results are good. A brief look at the spec sheets shows that insertion loss ranges for the lower-frequency DS38EP100 are around 1.1 dB at its 3.125 Gbit/s sweet spot and 1.5 dB for the DS80EP100 at a the 5 Gbit/s data rate supported by PCIe Gen II. Whatever the specific reasons for the equalizer performance, they certainly reinforce the fact that National was smart to maintain its Portland, Maine, fab facility and a few other plants that give it the ability to make the silicon do what they want it to and not what a third-party foundry feels like offering.

 

When I asked about whether they were considering introducing multi-channel devices, my handlers were as tight-lipped about the company plans for future products as they were about the details of their fab process -- but they did not deny that something was in development. They also hinted at offering application-specific products in the future that were fine-tuned for a particular use (ie specialized pinouts, equalization curves and impedances) although they did not talk about any specific plans.

In production now, the DS38EP100 is priced at $1.30 each and the DS80EP100 is $1.65 each, both in 1000-piece lots.

 

Data Sheet DS38EP100