Nujira Envelope Tracking DTV Broadcast Transmitter achieves 45% energy efficiency

According to Nujira’s CEO Tim Haynes, “Energy efficiency is one of the primary design challenges for the $500M broadcast transmitter industry. Today’s state-of-the-art transmitters operate only at 25-30% efficiency and with successive generations of RF devices improving only by a few percentage points, thus the ability for vendors to differentiate based on RF performance is limited. Our Envelope Tracking technology is set to change the competitive landscape of the industry, enabling OEMs to make an efficiency leap of more than 15 points, corresponding to a 35% reduction in energy costs and carbon emissions.”



Digital Terrestrial TV and Radio broadcasts are significant energy consumers, with each 5 kW transmitter typically consuming around 25kW of electricity, 24 hours per day. The majority of this energy is wasted in the form of heat dissipated by the RF Power Amplifier (PA) stage. Using Nujira’s Coolteq-u technology, an equivalent transmitter would consume only around 16 kW, giving annual energy cost savings of around $12,000 and reducing CO2 emissions by around 100 tonnes.







Nujira’s Coolteq UHF technology demonstrator is a compact 2U-high liquid-cooled rack incorporating Nujira’s Coolteq.u Ultra High Power Envelope Tracking modulator, which has been specifically developed for high power air- or liquid-cooled broadcast transmitters. The demonstrator also incorporates 50V LDMOS PA devices, a commercial RF driver, and low-loss RF combiners and splitters. The measurement results were achieved using Nujira’s adaptive Digital Pre-Distortion algorithms and a DVB-T signal with 8.0 dB Peak-to-Average Power Ratio. The frequency range of the technology demonstrator is 450-750 MHz.







The broadcast transmission network accounts for the majority of the total electricity used by a broadcaster, and over half of this is typically wasted by the RF PA device. Nujira’s Envelope Tracking solution replaces the fixed voltage DC:DC converters used in today’s transmitters, and dynamically modulates the supply voltage to the PA device to track the amplitude of the signal. By maintaining the PA in compression over the entire dynamic range of the signal, rather than just at the peaks, the energy efficiency is maximised.







The reduced heat dissipation in the PA also simplifies cooling requirements, reducing cooling costs and increasing the threshold at which water cooling becomes a requirement. Other benefits include smaller equipment size, reduced maintenance costs and improved equipment reliability, as well as reduced site installation and rental costs.