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Quantance, efficient radio frequency transmit circuits

Posted: 09 Dec 2008 ?? ?Print Version ?Bookmark and Share

Keywords:RF? 3G? Quantance radio frequency?

By Maciej Bajkowski

There is no doubt that obtaining funding for a semiconductor startup in this economy is anything but easysimply take a look at our post regarding Ambric's fiath. But not all is lost, as Quantance demonstrates; obtaining venture capital is still possible. Just a few days ago, the company managed to obtain $12 million in Series B funding from TD Fund, DOCOMO Capital, Granite Ventures, and InterWest Partners. Quantance intends to use this money to commercialize their patented radio frequency (RF) technology for 3G wireless devices.

We've covered quite a few startups targeting wireless devices this year: Black Sand Technologies working on silicon based power amplifiers, WiSpry developing programmable RF products, and finally BitWave Semiconductor and their Softranciever technologyobviously the wireless sector is hot. Quantance's goal is to improve the efficiency of RF transmit circuits in wireless products, and is shown in the figure.

As can be seen, the company intends to improve the efficiency in three ways. First, the company proposes a supply voltage loop which modifies the supply voltage of the power amplifier (PA) to track the RF signal modulation. Second, for this to happen, Quantance had to develop an ultra-fast, low noise, power converter. Finally, they also integrated a closed-loop correction system to correct the incoming signal before it reaches the PA. These three things should yield several benefits: Since the voltage to the PA no longer needs to constantly stay at an elevated level, the power consumption and heat dissipation for this solution should be lower than that of competing units. Quantance claims that battery current savings might be as high as 30-40% and temperature reduction could be as high as 50%. I would suspect that these savings are highly dependant on the peak-to-average ratio (PAR) of the incoming signal, as such, the numbers above don't really tell the whole story. Additionally, the company claims that their new approach will allow for a 20-30% increase in coverage range without an increase in battery drain.

Quantance's goal is to improve the efficiency of RF transmit circuits in wireless products.

These promised power-savings are likely music to the ears of mobile device developers, who are tired of consumers complaining about the shorter than expected battery-life of the current batch of 3G deviceswhich is probably why the company was able to score some more funding. Quantance's first chip, the Q1000, began sampling in Q2 of 2008 and is expected to enter full fledged production in Q2 of 2009. As mentioned before, initially the company will target 3G mobile devices, but eventually plans to address other potential markets such a long term evolution (LTE) and WiMAX devices.

Maciej Bajkowski is one of the featured bloggers at ChipCrunch.

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