The Role of Analog Design in the Broadband Era

Electronic News, Nov 13, 2000 by Alun Roberts

After years of industry preparation, the broadband revolution has finally achieved the deployment momentum it needs to make high-speed Internet access and other services a regular part of our lives.

More than 11 percent of American households now have abroad-band connection via TV cable or telephone line, according to market analyst Statistical Research Inc., Westfield, N.J. In ADSL alone, IC solutions for more than 20 million ports will be shipped this year worldwide, analysis firm International Data Corp., Framingham, Mass., estimates.

The availability of high-bandwidth services has spawned a related industry that is dedicated to reaching homes and small businesses with information. Wireless networks based on Bluetooth, 802.11 Ethernet and other standards are seeing early adoption and the race is on to create so-called Internet appliances that will spread network intelligence even further. It hardly needs saying that today's activity is only the tip of the iceberg: broadband services and the fan-out of information they make possible are still in their infancy. Before long, they will move from being a novelty to a necessity.

In many ways, the success of the broadband revolution reflects the triumph of high-speed digital technologies. DSL in its various forms and DOCSIS, the cable counterpart, are standards for digital transmission. Client modems and central office (CO) equipment such as DSL access multiplexers and digital loop carriers are based on high-speed DSPs. Client networking equipment is digital, as are the PCs that gobble up data as fast as the network connection can supply it.

With all these signs of digital success, it is easy to overlook the essential role played by advanced analog technology in making the broadband revolution possible. Digital signals have to be transmitted and received over twisted-pair or coaxial cable using high-speed line-driver receivers. With ADSL, the data rate and distance specifications impose tough performance requirements on line-drivers. This performance is critical because line-driver performance dictates how far the modem can be deployed from the central office while maintaining the required data rates.

High-drive and excellent noise characteristics are needed to achieve these specifications and CO concentration units impose constraints on power consumption as well. The line-driver consumes more than half the power of the ADSL chipset. By lowering the power used by line-drivers and other components, less heat is dissipated and more channels can be packed into the same space. Higher levels of integration can also save space and system costs; therefore, there is an ongoing challenge to pack more analog front-ends into fewer chips without raising costs.

ADSL is representative but not unique in its analog challenges. Cable transmissions have similarly strict requirements and small-scale wireless data networks such as Bluetooth are dependent on low-power analog technology for battery management and RF transmission. If analog technology could not meet specifications in all these areas, broadband and its fan-out networks would still be just a vision, instead of a fact.

For broadband OEMs, analog plays a fundamental role in their systems and can pose serious problems in development. The line-driver-receiver requirements of every system are unique, depending on complex factors that are intrinsic to analog design. And if good designers are always in short supply, good analog designers who can cope with these complexities are downright rare, so that an OEM can be faced with a development bottleneck when it comes time to implement the high-performance analog components of a system.

Fortunately for OEMs, leading analog vendors are working to shoulder a large part of the burden of analog design, enabling their customers to reduce time-to-market and allowing them to focus on the development of intellectual property to enhance their products. Vendors that offer the most to their customers are those with an edge in process technology and design talent as well as a portfolio of line-driver receivers, power supplies, data converters and other analog and mixed signal components that can simplify development.

When an OEM is searching for a line-driver or other analog solution, what must the vendor be prepared to provide? High performance is the baseline requirement, so an advanced analog manufacturing process is essential.

Yet the results of developing such a process go beyond high speed and low noise, critical as these performance characteristics are for applications such as broadband. A vendor with a strong underlying process is able to develop new products quickly. In an industry characterized by the presence of both giant OEMs and smaller niche players, the vendor must be able either to satisfy specific customer requests or take advantage of a market opportunity by introducing a new standard product. For instance, when basic telephone services over cable are introduced, it will be necessary to supply lifeline power as well requiring the introduction of line-drivers that can support this need. An advanced process is the enabling technology that allows the vendor to respond quickly to such changing needs.