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Summary:

The Nexus 5 is the second phone we’ve seen that incorporates envelope tracking technology, which has nothing to do with mail delivery. The technology greatly reduces the power needed to transmit an LTE signal.

The new Nexus 5 isn’t just packed with new software and performance features, it has some cutting-edge radio enhancements as well. The device not only supports CDMA, GSM/HSPA, 9 LTE bands and the new Wi-Fi stand 802.11ac in the same chassis, it also uses Qualcomm’s new envelope tracking technology, which could make the Nexus 5 a much more battery friendly and power-efficient phone.

Qualcomm’s envelope tracker, called the QFE1100, debuted in the Samsung Galaxy Note 3, making the Nexus 5 the second phone we know of to use the technology. Basically, the tracker matches the power fed into the signal amplifier to the power transmitted from the phone. Sounds simple, but it’s actually a very difficult thing to accomplish especially on LTE smartphones, which eat up far more power in their signal amplifiers than 3G or 2G devices.

Nujira envelope tracking

Qualcomm estimates its envelope tracker reduces the amount of heat put out by the phone by 30 percent and power consumption from the radio frequency components by 20 percent. Granted, that’s not overall power consumption on the device: The Nexus 5’s fully lit screen will do far more damage to its 2300mAH battery charge than the radio. But unlike the screen, the phone’s radios are constantly working in the background, signaling the mobile network, collecting email and social media updates and sending and receiving app data.

A growing number of RF front-end component makers such as Quantance and Nujira have developed and begun shipping their envelope tracking technologies, even though Qualcomm’s is the first to appear in the market. We’ll likely see many more phones with the technology in the coming year. As envelope tracking technologies improve they could cut power consumption in LTE phones by 25 percent – that’s overall performance, not just savings from the radio.

Nexus 5 angle

Qualcomm’s tracker is part of a new push by the chipmaker further into the radio guts of the phone. It launched a new front-end chip called the RF360, which can theoretically support as many as 40 LTE bands in the same device. The envelope tracker is part of RF360’s modular architecture, but it doesn’t look like LG and Google are using the RF360’s full capabilities.

The Nexus does have a sizable complement of bands, though its hardly a global phone. The North American version will work on the LTE networks used by AT&T, T-Mobile and Sprint (it connects to all three 4G networks in Sprint’s new Spark service), all Canadian operators, and a smattering of carriers in Asia. LG also produced a scaled down version for the rest of the world that supports only six European and Asian bands and does away with the CDMA radios.

The inclusion of 802.11ac in the Nexus is also significant. Few smartphones and tablets have the new technology, but it’s starting to make its way into enterprise and home routers and PCs. While you could make the argument that no smartphone can take advantage of 802.11ac’s enormous speeds, the additional capacity, efficiency and range of the new Wi-Fi standard will benefit all devices. But for that to happen, 802.11ac will need to make it into more mobile devices, since they’re now the biggest users of Wi-Fi.

Envelope tracking diagram courtesy of Nujira

  1. Nice article. This was news to me.

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