Improving Video Clock Generation in Modern Broadcast Video Systems
Alan Ocampo, Applications Engineer

The old adage "timing is everything" is well embodied in the modern broadcast studio, where precise timing of video clock and synchronization signals are essential to create, acquire, edit, and distribute analog and digital video. Today's broadcast systems must support industry-standard SD/HD formats, such as NTSC, PAL, 720p, 1080i, and 1080p, over analog and digital interfaces such as composite, component, and Serial Digital Interface (SDI). With high-speed SDI video equipment being increasingly used throughout the studio, improved video sync separation can more effectively produce video clocks with low jitter, which is crucial to meeting the stringent specifications of new SDI standards.

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NEW APPLICATION NOTES

• AN-1489 Techniques of State Space Modeling (pdf 511KB)

Multi-Format Video Sync Separator

The LMH1981 is a multi-format sync separator for high-definition broadcast and professional video systems. The device automatically detects the input video format and performs all the necessary sync separation to generate low-jitter horizontal and vertical sync signals for standard and high-definition video formats, including NTSC, PAL, SECAM, 480i, 480p, 576i, 576p, 720p, 1080i, and 1080p.

The LMH1981 features the timing outputs needed for any video system, including horizontal, vertical and composite sync, odd/even field, burst/back porch clamp, and a patented automatic video-format detection feature. The device accepts both bi- and tri-level sync video inputs and features 50% slicing to ensure accurate separation of signals that vary in amplitude, offset, and noise. The device has a wide input range, allowing the inputs to accept video signals from 500 mV_P-P to 2 V_P-P.

Features

• 50% sync slicing
• Low jitter horizontal sync output
• Supports NTSC, PAL, SECAM, 480i, 480p, 576i, 576p, 720p, 1080i, and 1080p
• Accepts video signals from 500 mV_P-P to 2 V_P-P
• No external programming with µC required
• Horizontal sync output propagation delay <50 ns </li /><50 ns

The LMH1981 is ideal for use in a wide range of video applications such as, broadcast video equipment, video distribution, DTV and HDTV systems, and is available in TSSOP-14 packaging.

Adaptive Cable Equalizer

The LMH0044 adaptive cable equalizer is a monolithic integrated circuit for equalizing data transmitted over cable (or any media with similar dispersive loss characteristics). The equalizer operates over a wide range of data rates from 143 Mbps to 1.485 Gbps and supports SMPTE 292M, SMPTE 344M, and SMPTE 259M. This device implements DC restoration to correctly handle pathological data conditions (DC restoration may be bypassed for low data rate applications). The equalizer may be driven in either a single-ended or differential configuration.

Additional features include separate carrier detect and output mute pins which may be tied together to mute the output when no signal is present. A programmable mute reference is provided to mute the output at a selectable level of signal degradation.

Features

• SMPTE 292M, SMPTE 344M, and SMPTE 259M compliant
• High data rates: 143 Mbps to 1.485 Gbps
• Equalizes up to 200m of Belden 1694A at 1.485 Gbps or up to 400m of Belden 1694A at 270 Mbps
• 208 mW typical power consumption with 3.3V supply
• Manual bypass and output mute with a programmable threshold
• Single-ended or differential input
• Supports DVB-ASI at 270 Mbps
• 50W differential outputs
• Single 3.3V supply operation

The LMH0044 is ideal for SMPTE 292M/344M/259M serial interfaces, serial digital data equalization and reception, and data recovery equalization. The LMH0044 is available in LLP-16 packaging.

Digital Video Serializer with Ancilliary Data FIFO and Integrated Cable Driver

The LMH0030 is a monolithic integrated circuit that encodes, serializes, and transmits bit-parallel digital video data. The serial data clock frequency is internally generated and requires no external frequency setting, trimming, or filtering components. The LMH0030 performs functions which include: parallel-to-serial data conversion, SMPTE standard data encoding, NRZ to NRZI data format conversion, serial data clock generation and encoding with the serial data, automatic video rate and format detection, ancillary data packet management and insertion, and serial data output driving.

Features

• SDTV/HDTV serial digital video standard compliant
• Supports 270 Mbps, 360 Mbps, 540 Mbps, 1.4835 Gbps, and 1.485 Gbps SDV data rates with auto-detection
• Low output jitter: 85 ps (typ), 125 ps (max)
• Low power consumption: 430 mW (typ) from 3.3V
• No external VCO required
• Fast PLL lock time: < 150 µs (typ) at 1.485 Gbps
• LVCMOS compatible data and control inputs and outputs
• 75W ECL-compatible, differential, serial cable-driver outputs
• 3.3V I/O power supply and 2.5V logic power supply operation

The LMH0030 SDTV/HDTV serial-to-parallel digital video interfaces for video cameras, VTRs, telecines, digital video routers and switchers, digital video processing and editing equipment, video test pattern generators and digital video test equipment, and video signal generators. The LMH0030 is available in TQFP-64 packaging.

Digital Video Deserializer / Descrambler with Video and Ancillary Data FIFOs

The LMH0031 is a monolithic integrated circuit that deserializes and decodes SMPTE 292M, 1.485 Gbps (or 1.483 Gbps) serial component video data, to 20-bit parallel data with a synchronized parallel word-rate clock. It also deserializes and decodes SMPTE 259M, 270 Mbps, 360 Mbps, and SMPTE 344M (proposed) 540 Mbps serial component video data, to 10-bit parallel data. Functions performed by the LMH0031 include clock/data recovery from the serial data, serial-to-parallel data conversion, SMPTE standard data decoding, NRZI-to-NRZ conversion, parallel data clock generation, word framing, CRC and EDH data checking and handling, Ancillary Data extraction, and automatic video format determination.

Features

• SDTV/HDTV serial digital video standard compliant
• Supports 270 Mbps, 360 Mbps, 540 Mbps, 1.483 Gbps, and 1.485 Gbps serial video data rates with auto-detection
• Low power: 850 mW (typ)
• Uses 27 MHz crystal or clock oscillator reference
• Fast VCO lock time: < 500 µs at 1.485 Gbps
• Built-in self-test and video test pattern generator
• LVDS and ECL-compatible, differential, serial inputs
• 3.3V I/O power supply and 2.5V logic power supply operation

The LMH0031 SDTV/HDTV serial-to-parallel digital video interfaces for video editing equipment, VTRs, standard converters, digital video routers and switchers, digital video processing and editing equipment, video test pattern generators and digital video test equipment, and video signal generators. Operating over the commercial temperature range (0°C to +70°C), the LMH0031 is available in TQFP-64 packaging.

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