Cellular Terminals: increasing battery life and reducing RF subsystem cost
The problems facing designers of RF subsystems for handsets and other cellular terminals have become increasingly challenging. The need to simultaneously support different systems (LTE, WiMAX, WCDMA, HSPA, MC-GSM etc.) in one handset, while supporting the increasing number of frequency bands, has resulted in significant increase in RF system complexity. At the same time, battery life continues to be a major issue with smartphones, tablets and other portable devices and will worsen with greater data consumption and always-on connectivity.
The traditional approach to these challenges has been to use a number of separate PAs (maybe up to 8 in current designs) within the handset RF subsystem, each covering a fairly narrow band, and optimized for peak efficiency for that band and the system being supported. This works well when only a few frequency bands are required, but quickly becomes very complex for multi-band, multi-mode handsets, with RF switching and thermal issues all making a compact, cost-effective solution extremely difficult to achieve.
Coolteq® Benefits
Applying Nujira's Coolteq technology to mobile terminals results in higher power efficiency, with a 50% reduction in PA power for the same RF output - leading to longer battery life and lower heat dissipation (especially for new standards such as HSUPA, LTE and WiMAX).
In addition, the technology enables a significant reduction in RF system architectural complexity, with fewer broadband PAs doing the work of many individual PAs - leading to reduced PA module cost and size. Nujira's HAT® technology is thus an essential enabler as LTE, WiMAX and HSUPA.
How it works
Nujira’s Coolteq.L power modulator ICs enable higher PA efficiencies to be achieved with just a few broadband PAs supporting multiple modulation types and frequency bands, allowing a fundamental re-thinking of the RF sub-system architecture. Cost effective broadband PAs are a key enabling technology for 4G handsets.
Coolteq.L is integrated within the RF PA module which can now contain just one or two broadband PAs to cover all the frequency ranges required. The drain voltage of each PA is dynamically varied in line with the modulation envelope, thus ensuring that the output device operates in near-compression (even at low output powers), and resulting in very high PA efficiency. The modulation envelope is derived from the digital (modulation) signal from the baseband system
Development System
Nujira’s Coolteq Flexible Development System (FDS) enables platform and RF Power Amplifier (PA) designers to begin PA development for systems using Nujira’s Coolteq-based Envelope Tracking technology. The Coolteq FDS can be configured for a wide range of applications including cellular handsets and dongles, cellular infrastructure, digital TV transmitters and military communications systems.
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