The High-Definition Multimedia Interface (HDMI) connectivity standard for transferring uncompressed digital content at very high rates over a single cable has come a long way. Last year's adoption of the HDMI version 1.3 release, with key performance improvements, has advanced the adoption rate of sources that provide 1080p resolution such as Blu-ray and HD-DVD. As its popularity grows, so does its list of supporters.
"HDMI has seen enormous growth and acceptance in 2006 and 2007," said Chris Chipman, product marketing manager of the advanced TV product line at Analog Devices. "HDMI-enabled products are shipping from an ever-increasing number of participants and market segments. Products include advanced TVs, AVRs, DVD players/recorders, Blu-ray and HD-DVD recorders, game consoles, set-tops, portable media players, digital cameras and HD camcorders. We expect this trend to continue in 2008 and beyond."
Indeed, major interface IC makers--Analog Devices Inc., Maxim Integrated Products, National Semiconductor, Pericom, Silicon Image and Texas Instruments--are clamoring to support HDMI's latest iteration with a variety of devices, such as receivers, transmitters, multiplexers and cable equalizers, that will enable the HD video market to achieve new levels of picture quality and power efficiency.
With HDMI version 1.3, the link speed of HDMI more than doubled from 165 MHz to 340 MHz, yielding additional bandwidth that can be used for deep color, higher refresh rates, greater resolution or all three.
"As seen in the evolution of interfaces over time, HDMI has improved with subsequent revisions so that today's HDMI 1.3a, with a total throughput of 10.2 gigabits per second, can handle many higher screen resolutions, and more bits can be allocated color coding--deep color--than the original, 4.95 Gbits/s," said David Mulcahy, interface product marketing engineer at Texas Instruments (Dallas).
Deep color eliminates banding effects by rendering each pixel color more accurately. The HDMI 1.3 specification requires that the data channels perform from 2 Gbits/s to 3.4 Gbits/s to provide 10 bits to 16 bits of deep color. The latest version of the HDMI specification, HDMI 1.3a, has also included a deep color specification that supports 30-bit, 36-bit and 48-bit RGB or YCbCr color depths.
HDMI 1.3 also carries lossless high-bit-rate (HBR) audio (Dolby, TrueHD and DTS HD Master Sound) for studio-quality reproduction of movies and music video on Blu-ray Discs and HD-DVD. HDMI 1.3 includes a new mini connector to expand the reach of HDMI into the mobile market; HD camcorders and digital still cameras are the first products to market using the new connector, according to Silicon Image.
Silicon Image (Sunnyvale, Calif.) continues to garner design wins for its SiI9125, SiI9134 and SiI9135 products, which it claims were the first products to deliver HDMI 1.3 deep color. The VastLane SiI9135 HDMI 1.3 receiver is designed for use in A/V receivers and supports HBR audio, which enables A/V receivers to play back compressed lossless audio formats such as Dolby True HD and DTS-HD. The VastLane SiI9125 is a dual-input HDMI receiver that fits directly into HDTVs, offering manufacturers a drop-in upgrade to add HDMI 1.3 capabilities to their HDTVs.
Analog Devices' ADV7520NK transmitter packs consumer electronics control (CEC) support on chip. |
In the consumer electronics market, the move to LCD, plasma and DLP digital TV displays; the rapid adoption of the 1080p standard for HD; and the upcoming transition from analog to digital broadcasting in most parts of the world indicate that HDMI is already the interface of choice for TV.
"We see this already with gaming consoles, camcorders and DVD players," said Mulcahy of Texas Instruments.
TI offers a variety of interface chips that support HDMI mux and buffer functions. The recently introduced TMDS351 and TMDS251 video switches for HDMI 1.3a switch between either two or three digital video signals coming from devices such as game consoles, set-top boxes or DVD players to a single HDTV display. TI offers 8-kV HBM ESD protection on the video carrying TMDS lines. In addition, the devices support switchable termination, which offers designers added flexibility of system implementation.
At Analog Devices (Norwood, Mass.), HDMI chip developments occur regularly. The chip maker recently developed a low-power HDMI 1.3 transmitter for portable media and DVD players, video recorders and other mobile multimedia devices capable of supporting HD A/V content. The ADV7520NK was the first HDMI transmitter to include a CEC (consumer electronics control) buffer on-chip. That re- duces component count, eases design complexity and speeds time-to-market for portable high-definition devices by eliminating the need to develop a separate CEC support channel.
National's DS16-EV5110 extends HDMI's reach beyond 20 meters of 28 AWG. |
The ADV7520NK is one of many HDMI offerings from Analog Devices, which also offers 10-bit integrated RGB graphics digitizers and dual HDMI/DVI receivers, as well as HDMI switches and buffers with equalization. "High-performance input equalization [enables] even longer cable lengths," Chipman said.
Low power is a key enabler for portable applications. Analog Devices offers what Chipman says are the lowest-active- and standby-power HDMI transmitter products available. Its ADV7520NK HDMI transmitter includes 5-V-tolerant I/Os that support I2C and hot-plug detect, further simplifying system design and extending battery life in portable electronics by eliminating external voltage translator chips to convert I/O signals from 5 V to either 1.8 V or 3.3 V.
Since cables have finite bandwidth, higher data rates will experience more inter- symbol interference (ISI) for a given length of cable, according to Philip Marzolf, HDMI marketing manager at National Semiconductor.
ISI leads to increased amounts of deterministic jitter, which can compromise the quality of data transfer with bit errors. Therefore, even though HDMI is capable of supporting very high data rates, cable interconnect limitations place an upper limit on the achievable throughput realized by the end user. Overcoming that obstacle requires high-performance analog signal processing.
Cable equalizers compensating for ISI can increase interconnect reach by an order of magnitude compared with nonequalized interconnects. Leveraging National's extensive signal processing expertise and advanced process technology, the DS16EV5110 video equalizer extends the reach of HDMI connections to more than 20 meters of 28 AWG cable at data rates as high as 2.25 Gbits/s.
The DS16EV5110 provides programmable linear equalization for three TDMS data channels while consuming low power. Since ISI is directly dependent on
the interconnect length, the DS16EV5110 provides a simple mechanism allowing manufacturers to select the optimum equalization for their particular needs. The DS16EV5110 features a total jitter of 0.13 unit intervals (UIs), a figure that was achieved using National's proprietary BiCMOS-8 technology. The equalizer supports digital TV resolutions of 480i/p, 720i/p and 1080i/p, as well as all computer resolutions, from Video Graphics Array to Wide Quad Extended Graphics Array.
But while HDMI is the most popular digital video interface in the consumer electronics sector, different standards will be adopted in other markets. "For example, we see DisplayPort becoming important in the PC space," TI's Mulcahy said.
TI, Pericom Semiconductor and others are preparing devices to support DisplayPort, a new digital display interface standard that is gaining momentum in the PC industry.
"This is being driven by next-generation Intel chip sets such as Cantiga for NB PC and Eagle Lake for DT PC," said Shaf Rahman, senior director for switch and interface products at Pericom Semiconductor Corp. (San Jose, Calif.). "Most of the major PC manufacturers are already developing systems based on DisplayPort at this point."
Developed by a VESA Task Group to unify the desktop and notebook PC markets, the DisplayPort standard allows HD digital audio to be available to the display device over the same cable as the digital video signal. It enables, for the first time, a common interface for both external and internal display connections in a notebook or desk- top display.
Pericom recently introduced the PI3VDP411LS electrical Display Port-to-DVI/HDMI bridge, which converts four-differential low-swing ac-coupled inputs to HDMI rev 1.3-compliant outputs.
It also features a 5-V to 3.3-V DDC and HPD level shifter; HDMI level-shifting operation up to 2.5 Gbits/s per lane (required for 36-bit-deep color); and integrated 50-ohm termination resistors to support ac-coupled differential inputs.