Wireless local-area networks (WLANs) are proliferating almost as fast as the number of WLAN standards. At present, several 5-GHz bands are earmarked for high-data-rate WLANs within the UNII band from 5.15 to 5.85 GHz, including IEEE 802.11a and 802.11g. Normally, a separate power amplifier (PA) would be needed for each WLAN band. But with the availability of the model RMPA5251-251 WLAN PA from Raytheon RF Components (Andover, MA), a single amplifier can now handle all WLAN applications within the 4.9-to-6.0-GHz band.
The RMPA5251-251 is an InGaP heterojunction-bipolar-transistor (HBT) amplifier nominally designed for high-performance WLAN applications from 5.15 to 5.35 GHz. It is also capable of providing high gain and linear output power in the lower UNII band from 4.90 to 5.35 GHz and in the higher UNII band from 5.15 to 5.85 GHz. From 5.15 to 5.35 GHz, the linear PA features 27-dB small-signal gain and +26 dBm (single-tone) output power at 1-dB compression when operating from +3.3-VDC supply.
The PA provides excellent performance with modulated carriers, judging from its error-vector-magnitude (EVM) performance. When evaluated in its low-band (4.90 to 5.35 GHz) configuration for +17-dBm modulated output power in IEEE 802.11a 54-Mb/s operation, there is less than 3.5-percent increase in EVM above the system level. Testing was performed with VM of +3.3 VDC, VC of +3.3 VDC, IC of 188 mA and IM of 16 mA, assuming a 16.7-MHz channel within the 4.9-to-5.35-GHz band.
The RMPA5251-251 requires only nine additional external components for low-band operation from 4.90 to 5.35 GHz. By changing two external biasing components, the amplifier can be optimized for operation over the full UNII band from 5.15 to 5.85 GHz, with 28-dB single-tone gain, better than 8-dB return loss, +25 dBm single-tone output power at 1-dB compression, EVM of less than 3.5 percent at +18-dBm modulated output power. The PA can also be matched for operation from 4.9 to 6.0 GHz.
The RMPA5251-251 is supplied in a low-profile 16-pin 3 × 3 × 1-mm standard QFN leadless package. For applications requiring amplification of 2.4-GHz IEEE 802.11b signals as well as IEEE 802.11a/g, the company also offers the RMPA2550-252 PA in a 3 × 4 × 1-mm QFN leadless package. Also, the RMPA2453-251 PA is available for just the 2.4-to-2.5-GHz coverage. P&A: $2.50 (RMPA5251-251, 100,000 qty.). Raytheon RF Components, 362 Lowell St., Andover, MA 01810; (978) 684-5342, FAX: (978) 684-8646, Internet: www.raytheonrf.com.