company blog about TI LMH1228RTVT 12G UHD-SDI Dual Output Cable Driver With Integrated Reclocker

Shenzhen Mingjiada Electronics Co., Ltd. supplies the TI LMH1228RTVT 12G UHD-SDI dual-output cable driver with an integrated re-clocker.

I. Overview of the LMH1228RTVT Device

The LMH1228RTVT is a single-chip integrated solution developed by Texas Instruments (TI) for professional broadcast ultra-high-definition video. It combines a wide-bandwidth CDR (Clock Data Recovery) re-clocker, adaptive input equalisation, two 75Ω coaxial cable drivers and a 100Ω differential loopback monitoring output, It natively supports serial digital signal transmission of up to 11.88 Gbps 12G UHD-SDI 4K/8K ultra-high-definition signals, providing a one-stop solution to the challenges of jitter degradation, signal attenuation and multi-channel distribution in long-distance coaxial transmission. The model suffix ‘RTVT’ denotes a 5mm × 5mm, 32-pin WQFN bare-pad package, making it the mainstream core signal conditioning chip for broadcast switching systems, distribution amplifiers and live broadcast equipment.

Traditional SDI signal chains often require separate equalisers, clock recovery chips and multi-channel drivers—three-stage components—resulting in large circuit footprints, jitter accumulation and complex debugging; the LMH1228RTVT streamlines the BOM through a highly integrated architecture, incorporating a full-rate phase-locked loop and compensation network, enabling a single chip to handle signal reception, clock re-synchronisation and dual-channel coaxial distribution, thereby significantly simplifying high-speed video hardware design.

II. Core Hardware Specifications of the LMH1228RTVT

1. Full-format compatibility for transmission rates

The on-chip re-clocker automatically locks onto all SMPTE standard rates without the need for an external reference clock:

11.88 Gbps (12G UHD-SDI, 4K60p 10-bit), 5.94 Gbps (6G-SDI 4K30p)

2.97 Gbps (3G-SDI), 1.485 Gbps (HD-SDI), 270 Mbps (SD-SDI)

Compatible with 1.001× sub-rate (adapted for the NTSC 29.97 Hz standard), whilst also supporting DVB-ASI and AES10 MADI digital audio data stream transmission.

2. Power Supply and Packaging

Single 2.5V power supply (operating range 2.375V–2.625V), typical power consumption 305mW; automatically enters low-power energy-saving mode when no input signal is present, with standby power consumption of only 25mW

Package: 32-WQFN (RTVT), compact 5×5 mm size, with bare pads for enhanced heat dissipation, suitable for high-density board layouts

Wide operating temperature range: -40°C to +85°C, suitable for harsh environments such as studios, outdoor broadcast vehicles and equipment rooms.

3. Interface Output Architecture

Input: Single-channel differential IN0±, with an integrated adaptive PCB continuous-time equaliser (CTLE) to compensate for high-frequency losses in FR4 traces

Line-side dual outputs: Two independent 75Ω differential cable drivers (SDI_OUT1/OUT2), with on-chip integrated 75Ω termination and return loss compensation networks, eliminating the need for external precision matching resistors

Host Monitoring Output: One 100Ω differential loopback channel (OUT0±) with re-clocking and re-shaping, intended for on-board signal monitoring, secondary distribution and oscilloscope debugging; supports programmable de-emphasis and amplitude adjustment.

III. Detailed Explanation of Core Functional Modules

1. Integrated Clock Data Regenerator (CDR Reclocker) — Key Advantage

Clock data regeneration is the key feature that distinguishes the LMH1228RTVT from standard SDI drivers: after travelling through long cables or PCB traces, signals accumulate random jitter and intersymbol interference; distributing them directly to multiple devices can result in eye diagram closure, image noise and screen distortion; The built-in CDR loop filter strips high-frequency jitter from the input signal, regenerating the data using the chip’s internal clean, low-jitter clock. The output jitter performance is far superior to that of the original input signal; jitter does not accumulate during multi-stage cascading, ensuring synchronisation and distortion-free transmission across multiple devices.

Automatic rate recognition and locking eliminate the need for software configuration to switch modes; the LOCK_N pin outputs a lock status indication, facilitating system fault diagnosis.

No external passive loop filter components are required, resulting in a highly simplified peripheral circuit and reduced component and debugging costs.

2. Adaptive Signal Compensation Drive System

Input equalisation: Built-in adaptive CTLE equalisation automatically compensates for high-frequency attenuation in PCB traces, enabling stable locking of 12 Gbps signals even after passing through 20-inch FR4 backplane traces

Intelligent optimisation of 75Ω coaxial output: automatic slew rate control, pre-emphasis and adaptive output amplitude to accommodate coaxial cables of varying lengths; supports output polarity inversion, ensuring compatibility with scenarios where on-site cabling polarity is reversed

All output channel parameters can be programmed via three methods—hardware pins, SPI and SMBus—to accommodate automated end-to-end calibration processes.

3. Built-in Eye Pattern Monitor (EOM)

The integrated Eye Opening Monitor quantitatively measures signal eye opening margin in real time, outputting a quantified index of 0–100% to a register. The MCU can read the link health status in real time, enabling remote fault early warning, cable ageing detection and automated factory testing, thereby significantly reducing the complexity of equipment operation and maintenance. This is a standard feature for intelligent diagnostics in broadcasting equipment.

IV. Core Advantages of the LMH1228RTVT Product

1. High Integration, Minimal Hardware

Combines equalisation, CDR re-clocking, dual-channel coaxial drivers and loopback monitoring into a single chip, replacing multi-chip discrete solutions. This reduces the number of PCB layers, minimises board footprint and lowers component procurement and soldering costs.

2. Exceptionally Robust Signal Integrity

Reclocking reconstructs a clean data stream, preventing the accumulation of jitter across multiple cascaded stages; the built-in impedance compensation network ensures 75Ω/100Ω output matching accuracy that meets the stringent SMPTE standards, eliminating echo interference during long-distance transmission.

3. Universal Support for All Standards, Cross-Scenario Compatibility

A single hardware solution supports all SDI specifications—SD, HD, 3G, 6G and 12G—whilst also being compatible with professional digital audio (MADI) and digital broadcasting (ASI), enabling a single device to cover all services from standard definition to 8K.

4. Flexible and Controllable, Suitable for Automated Production Lines

Configurable via three modes—pin-based hard control, SPI and SMBus—it supports automatic power-saving upon signal loss, channel switching, and dynamic adjustment of amplitude and weighting, making it suitable for intelligent switchers and modular plug-in devices.

5. Compact Package, Wide Temperature Range and High Reliability

The 5×5 mm WQFN package is suitable for high-density rack-mount enclosures; with an industrial-grade wide temperature range and excellent heat dissipation via exposed pads, it ensures stable, continuous operation in data centres 24/7.

V. Typical Application Scenarios for the LMH1228RTVT

1. Core Equipment for Broadcast Studios

4K/8K video switching matrices, SDI distribution amplifiers, signal repeaters, multi-screen splitters, and video processing and editing boards.

2. Live Broadcasting and Remote Production

Signal interface cards for OB broadcast vehicles, REMI remote production systems, on-site camera signal distribution, and portable live streaming equipment.

3. Professional Audio-Visual Infrastructure

MADI digital audio routing, DVB-ASI broadcast signal distribution, studio monitor signal distribution units.

4. High-End Professional Imaging Equipment

Cinema projector signal output extension, medical 4K endoscope image transmission, high-speed image link conditioning for industrial machine vision.

VI. Summary of the LMH1228RTVT

With its integrated design featuring 12G full-rate re-clocking, dual 75Ω coaxial drivers, adaptive equalisation and built-in eye diagram diagnostics, the LMH1228RTVT has become the benchmark signal conditioning chip for professional ultra-high-definition SDI transmission links. This single-chip solution addresses the four key challenges of high-speed video transmission—attenuation, jitter, multi-channel distribution and link diagnostics—whilst balancing hardware simplicity, signal quality and system intelligence. It is the component of choice for 4K/8K broadcast equipment, professional film and television production, and high-speed digital media transmission systems.