femtocells industry
providing femtocell products that implement different standards and operate over different frequency bands.
PA module designers want amplifiers that combine linearity with adequate RF power for good coverage and the capability of handling high capacity waveforms with high peak-to-average ratios (PAR). The PAs that we produce excel on all these fronts, uniting high power with outstanding linearity, plus good thermal performance for high reliability. As expected, these products draw on the many years of experience that we have in developing PAs for mobile handsets and broadband infrastructure products.
One of our primary goals is to create modules that combine extremely linear performance with a full complement of functional integration. To realize this ambition, we exploit the native efficiency and broadband capabilities of GaAs devices, and turn to state-of-the-art RF circuit simulation and thermal analysis tools to design the circuitry.
Since small cell products are available in several transmit powers, we developed single-ended and balanced PA modules with common features for each of the popular wireless bands. Earlier this year we released our first PAs for the small cell market, the AWB7123 and AWB7127, a pair of singled-ended parts with average powers of +24.5 dBm.
Before the year is out we will launch balanced equivalents of these modules. These two additions - the AWB7223 and the AWB7227 - operate at frequencies centered on 1.9 GHz and 2.1 GHz, respectively. They deliver a linear output of +27 dBm, which is more than adequate to cover a home or small office space. The modules operate at 4.5 V, and can handle a high peak-to-average ratio (PAR) waveform, making them ideal for networks employing CDMA, WCDMA or LTE technology. All of these products take advantage of the capabilities of our patented InGaP-Plus technology.
The remainder of this article will focus on the higher- frequency, balanced PA module: the AWB7227. Measurements show that this device can deliver a high level of performance when driven with a WCDMA signal (see Figure 1). Even when this module is driven with the
Figure 3. When designing the AWB series, the engineers at Anadigics had one eye on the future. As mobile carrier technology evolves, it is likely that the frequency division duplex LTE protocol will be used widely. The AWB7227 is capable of making this transition, as shown by this measurement with a 10 MHz, fully filled 64 QAM (50RB) test model
most demanding conditions, such as a ‘Test Mode 1’, 64- channel waveform with a PAR of 10.5 dB, there is headroom to the standards requirements. Figure 1 shows there is performance margin to the adjacent channel power (ACP) requirement, so there is no need to back-off the PA from its rated power to meet the ACP requirement at the antenna. Additionally, the module has integrated matching networks so it’s extremely easy to use.
The AWB7227 is also capable of supporting multi-carrier operation (see Figure 2). This provides deployment flexibility to mobile operators by providing handoff options. This feature will become even more important as the number of femtocells increases.
Future proof technology As air interfaces evolve, the associated technology must keep pace. The PA module is certainly affected by these
To prevent the AWB modules from becoming ineffective as the latest standards are deployed,we have designed them with the future in mind.Thanks to this approach, we have enabled the creation of femtocells that can adapt to standards and support migration and growth strategies.
October 2010
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