The dramatic growth in professional broadcast and consumer digital video – and thus the peripheral circuitry they also require – has put vendors of high-performance analog/mixed-signal ICs, as well as basic power-related components, in a very attractive position. It's yet another example of the ironic situation of high-profile, glamorous digital applications driving low-visibility, high-margin analog opportunities.
According to IHS Technology, the global market for professional broadcast equipment and services reached $63 billion in 2013, up 52% from $41 billion in 2007. The rapid growth has been driven by a significant rise in shipments of customer-premises equipment (CPE) fueled by the digitization of pay TV subscribers. Studios are ripping out thick bundles of low-speed copper cable built up over decades and replacing them with slender copper interconnects (coax and twisted pair) and even optical-fiber cabling, all carrying digital video (and audio) in serialized format.
The digital video broadcast/professional world involves high-speed serial data links between functional blocks. (Source: Texas Instruments).
Video from multiple sources is serialized and multiplexed onto a single cable at the source, and de-multiplexed at the other end, while all routing and switching among sources and users is handled by compact, computer-controlled routers.
Unlike some markets, this potential customer base is not dominated by a relatively small number of OEMs. Noted Tom Morrod, senior director for Consumer Electronics and Video Technology at IHS, “Owing to the multitude of broadcasters and pay-TV operators in each country, there is a very diverse market of small to medium companies offering solutions in the industry,” with the top ten vendors of professional video gear accounting for just 28% of all market revenue in 2013.
Certainly, the powerful processors (whether built as custom ASICs or FPGAs) that are needed to encode, encrypt, decrypt, decode, and parse the digital torrent get most of the analysts’ and media's attention. Yet once again, it takes an array of analog/mixed-function ICs and driver/receiver circuits to manage and transfer these bit torrents in the real world of cables, connectors, and interfaces.
If everything video-related is either going or has gone digital, why is all this analog functionality needed? It's simple: it's the laws of physics, and it's impossible to get around them. Every time a digital signal goes from point A to point B, the data bits – binary 0s or 1s represented by the presence or absence of a voltage pulse – are corrupted and distorted. Depending on the distance between points A and B – which could be as little as a few millimeters of interconnect between ICs, centimeters of PC-board traces, or meters of cabling and connector – the digital source must supply the necessary voltage level and drive current, to make the digital-signals transition fast enough so the result at the far end is recognizable as that original 1 or 0. The problem is magnified greatly at the higher speeds of these signals, which can reach into the Gbit/second range.
The problem is further aggravated as signal-path distance increases due to long cables, as their inherent capacitance and inductance imposes two related distortions on what started out as a sharp and fast binary signal. First, the crisp rise and fall transitions of the original waveform are slowed down, rounded, thus degrading it. Second, because pulses are not a single-frequency signal, the various frequencies contained in each pulse are delayed by different amounts, resulting in signal distortion. This combination of impediments forces the data link to throttle down to slower speeds to maintain acceptably low error rates, unless special equalization and synchronization circuitry is used.
[Of course, it's not just the vendors of analog-interface components who see opportunity, as these studio and consumer boxes need numerous power supplies and rails of different supplies in multiple sections of their boards and boxes, with voltages spanning modest single-digit values (such as 1.3V, 3.3V, 5V) to double digits (12V, 15V) and sometimes higher. ]
In the professional studio, the Serial Digital Interface (SDI) standard defines signal routing in most installations. The analog functions required include adaptive equalizers that dynamically adjust and correct for cable distortion; re-clockers to reestablish timing signals; line drivers that provide the needed voltage and current for putting digital signals on a cable, the complimentary line receivers that extract them, and cross-point switches that route the signals among various input and output ports.
Signal transport in professional video installations is based on the SDI (Serial Digital Interface) standard. Each interconnection point needs suitable line drivers, receivers, and other analog/mixed-signal circuitry (Source: Texas Instruments).
It's not just professional studios that need sophisticated analog components for digital video. Consumer multimedia systems are calling for many of these functions, based on the High-Definition Multimedia Interface (HDMI) standard for interconnection between units such as a DVD player and video screen.
Even a consumer multimedia center has significant signal-path complexity to manage, beginning with the HDMI standard for interconnection (Source: Analog Devices).
The complexity of the video-signal handling and routing, and the need for analog/mixed-signal/digital IC designs, is exemplified by the Analog Devices ADV7623. This quad-input, single-output transceiver device integrates HDMI receiver and transmitter with digital audio inputs and outputs onto one IC. In addition, it supports all repeater functions for HDCP, (High-bandwidth Digital Content Protection, commonly referred to as High-Definition Copy Protection), a digital copy-protection and digital-rights management system developed and licensed by Intel Corporation to prevent copying of digital audio and video content as it travels across connections.
The Analog Devices ADV7623 IC integrates HDMI receiver and transmitter functions as well as other functions, and also embeds HDCP digital copyright protection.
At the same time, analog vendors know that while their components are indeed indispensable, they are not the focus of digital-video designers' efforts, which usually emphasize software and application modules. These customers want complete chipsets, development kits, and reference designs, and that's why analog vendors have teamed with FPGA vendors.
For example, Texas Instruments has developed triple-rate SDI and video-clocking daughter cards for Altera's FPGA development kits. The cards plug into the host FPGA development board via Altera's high-speed mezzanine connector. The kits include FPGA source code for processing to the SMPTE (Society of Motion Picture and Television Engineers) protocol. The FPGA IP, along with the daughter cards and the development kit, provide broadcast-video system designers with a comprehensive platform for rapid evaluation and prototyping of new designs to reduce time to market.