The Portland, Oregon, based RF semiconductor company will imminently start addressing strong demand for its HV-HBT cellular base station amplifiers.

TriQuint Semiconductor is to start commercial production early in 2009 on GaAs amplifier products that have recently claimed a cellular base station efficiency record.

Low-volume initial production will begin on high-voltage HBT (HV-HBT) devices and ramp into 2010 in response to a strong interest in the technology’s power-saving potential.

“I've got more customers coming to me asking for samples, data and evaluation boards than I can possibly deal with today,” Doug Slansky, TriQuint's base-station product marketing manager, told compoundsemiconductor.net.

In October, Donald Kimball of the University of California, San Diego, (UCSD) presented results underlining the technology’s efficiency at the Compound Semiconductor Integrated circuit Symposium (CSICS).

At that Monterey, California, event Kimball used a method previously responsible for GaN and silicon LDMOS performance records to even better effect with HV-HBT devices.


Samples from TriQuint provided record average power added efficiency (PAE) above 58 percent at 42 W average output power and 10.2 dB gain in a single-stage wideband CDMA base-station PA.

“One source of the improved efficiency is the lower on-resistance encountered with HV-HBTs,” Kimball wrote.

Envelope Tracking
UCSD uses an approach called envelope tracking that dynamically controls supply voltage to minimize the power consumed by a PA. The actual output of a base station PA varies with demand, but base stations often maintain a single constant supply voltage regardless.

In envelope tracking, the supply voltage is adjusted to levels much closer to those actually needed at any time by the PA, reducing power loss from the system. To take most advantage of this, an amplifier should be efficient across all the supply voltages that the envelope tracking system varies through.

“GaAs HV-HBTs are attractive options since they can provide high efficiency and gain over a wide dynamic range,” said Kimball.

Envelope tracking is not an exclusive technology to UCSD, and is now under development at companies across the globe, although it is not yet being commercially deployed.

“We've been talking HV-HBT technology to all of the major base station manufacturers,” explained TriQuint's Slansky. “Most of them are looking at envelope tracking as a next-generation technology, or maybe one and a half generations from now.”

In the interim, the company will offer discrete HV-HBT products that it has also tested in a Doherty configuration, another efficiency-boosting approach.

“Discrete output stage transistors from 50 W to 250 W, at several power levels, will be offered for most major cellular bands,” explained Slansky.

“The first level of product offering will be discrete devices targeting the final PA stage, where the biggest efficiency impact is, because that is where most of the power is consumed.”

Richard: TriQuint的上一个新闻，关于PowerBand，我不是很明白其原理，不过这个HV-HBT的高效率，我明白了。这里说到高效率的一个来源是HBT导通电阻的减小，若放在几周之前，我也仍然不明白为什么；上上周推导了那个公式，知道了Ron对于器件效率的作用--其实在IV图上就可以很直观地看出来，只是从来没有从那个角度去看。这里还提到了Envelope Tracking，即所谓的“包络跟踪”技术，作为一种提高效率的手段，这个技术很好理解：高输出功率的时候高偏置电压，地输出功率的时候低偏置电压，从而使平均效率始终较高。但是反馈控制的问题始终没有很好解决，所以还未大规模商用，不过看样子指日可待了。还提高Doherty，这也是效率提高的一种技术，用得很多了，不叙。

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RSS里还看到RFMD的两则消息：BiFET技术原理及英国工厂裁员30%。看起来RFMD的BiFET工艺，还是比较好理解的，不是很复杂。只是在常规HBT外延片上添加两层（位于Emitter层之上）左右腐蚀阻挡层和JFET的沟道层；而工艺步骤也仅仅是增加了一次Mask和一次腐蚀，所以成本应该没有什么大的变化。至于性能，则肯定有些许的degrade，不过，最好的设计往往就是最好的折衷，无可厚非。裁员30%，只是又给半导体黑色寒流又推波助澜一把。什么时候情况可以好转呢？

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年关将至，死线也将至。可怜我们的电脑，每天被不间断地折磨，即便是在我们回去睡觉的时候，它们仍然不知疲倦地给我们干活。