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Power Amplifiers: Nujira CMOS could spell the end for GaAs

The silicon based CMOS power amplifiers, which use envelope tracking, boost the linearity, efficiency and output power for CMOS PAs beyond the performance of gallium arsenide PAs
UK based firm Nujira has released the details of significant test results that demonstrate how ET technology unlocks the potential of RF CMOS PAs for high end 3G and 4G smartphone applications.

Nujira CMOS chip

The firm is a specialist in Envelope Tracking (ET) technology.

Envelope tracking is an approach to RF amplifier design in which the power supply voltage applied to the power amplifier is constantly adjusted to ensure that the amplifier is operating at peak efficiency for the given instantaneous output power requirements.

Traditional CMOS PAs suffer from low inherent linearity, limiting their application to low cost 2G and 3G devices. ET removes this limitation and boosts the linearity, efficiency and output power for CMOS PAs beyond the performance of today’s GaAs PAs, even for high linearity LTE signals.

Extensive lab testing by Nujira has shown that the combination of the firm’s ET power modulators and a prototype CMOS PA device achieves the performance required for 4G. The key metrics achieved were 57 percent efficiency, 28dBm average output power, and -38dB ACLR, with a high peak-to-average power ratio LTE signal.

These high end performance results have been made possible by Nujira’s patented ISOGAIN Linearisation. ISOGAIN removes the need for Digital Pre Distortion in CMOS PAs and linearises the PA at no extra cost, power or complexity, while keeping the device in a highly efficient compressed state across a wide power control range.

By demonstrating the potential for high end applications of CMOS PAs, Nujira has opened the door for what is set to be a hugely disruptive technology shift in the RF market.

Tim Haynes, CEO of Nujira comments, “The exploding complexity of the RF front-end in today’s smartphones is driving unprecedented rates of change in the component industry. Our test results are a significant breakthrough, demonstrating that CMOS PAs can also be used in high-end 3G/4G smartphone applications. The combination of CMOS PAs with Nujira’s patented ET architectures could ultimately signal the death of the GaAs industry for handset applications. In the longer term, these results open the door for further CMOS integration, enabling a highly integrated RF front-end architecture for complex multi-mode, multi-band handsets.”

Nujira’s mission is to dramatically improve the energy efficiency of transmitters for 3G and 4G handsets, base stations and TV broadcast applications by reducing the amount of waste energy dissipated as heat in the RF Power Amplifier circuit. 

Nujira’s patented Coolteq Modulator technology dynamically controls the power supply to the circuit in line with the amplitude of the signal, enabling the creation of highly efficient RF Power Amplifiers.

Today Coolteq technology powers the industry’s most energy efficient and highest performing 4G base stations and TV broadcast transmitters. Nujira is now applying the same energy efficient technology to smartphones and other portable wireless devices.

A fabless semiconductor company located in Cambridge, UK, with design centres in Cambridge and Edinburgh, Nujira is enabling the design of cost-effective multi-mode, multi-band handsets that deliver faster data rates, longer battery life, and better coverage.

Nujira Woodstock Block Diagram
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