PMC-Sierra has decided to use a proprietary DSP architecture to deliberately distort wireless signals in a bid to improve the chances of good reception at the handset.
The DSP will be used in a range of devices aimed at wireless infrastructure equipment that supports major third-generation (3G) standards, such as wideband CDMA, cdma 2000 and Edge.
The Paladin-10, standing for power amplifier lineariser and distortion inhibitor, is the first chip in a series planned by the Canadian company that uses the adaptive predistortion technology for wideband multi-carrier systems that it acquired through the purchase of Datum Telegraphic in June.
Kevin Huscroft, chief technology officer and acting vice-president and general manager of PMC-Sierra's newly formed wireless products division, said: "We believe this off-the-shelf chip represents the lowest cost per watt solution yet for 3G systems, since it eliminates transmitter distortions and improves spectral efficiency in base transceiver stations."
Huscroft says that analogue power amplifiers are the most expensive components in wireless base stations, "so technology like ours is critical to the cost-effectiveness of these next-generation systems".
Networks will have to be built with higher performance and more efficient power amplifiers, able to support both voice and wideband data transmitted using packet-based protocols, he adds.
At the heart of the pre-distortion system is the PM7800 digital correction signal processor (DCSP), which works with firmware running in a separate DSP. The firmware, which will run on a standard DSP in the first implementation, uses samples of the signal after it has passed through the transmitter chain and power amplifier to calculate predistorted waveforms that compensate for distortion in those circuits.
The DCSP predistorts wireless signals in realtime using stored correction parameters that have been created by the slower, more complex firmware.
Huscroft says the device relies on very high-speed complex operations that can only be provided by proprietary application-specific DSP elements inside the DCSP.
The signal conditioning deals with analogue impairments such as wideband group delay, thermal and envelope memory dependencies, and bulk amplitude-amplitude modulation, as well as amplitude-phase modulation effects in transistors that cause in-channel distortion and adjacent channel interference.
The company says the chip does away with manual amplifier calibration by automatically adapting to, and compensating for, each amplifier's specific distortion pattern. This also eliminates the need for tuning and alignment.