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Targeting next-generation cellular (CDMA, GSM/GPRS/EDGE, W-CDMA, and WiMAX) infrastructure, CATV and other broadband wireless communication systems, WJ Communications Inc. has released a new family of small signal, high-performance broadband amplifiers. Labeled WJA, this broadband amplifier line uses high-reliability InGaP/GaAs heterojunction bipolar transistors (HBTs) to span a frequency range of 50 MHz to 4 GHz. It also offers high linearity with broadband performance and low current consumption in a small SMT package.

The new amplifier family includes both RF and IF devices. While WJA10xx amplifiers are designed for the RF band, the WJA15xx series is tailored for the IF space. At 900 MHz, the WJA1000 typically provides 19 dB gain, +37 dBm OIP3, and +19.5 dBm P1 dB. WJA10xx members cover a frequency range of 50 MHz to 4 GHz. Current consumption at room temperature is 78 mA at 5 V supply. Likewise, at 200 MHz, WJA1500 typically provides 20 dB gain, +43 dBm OIP3, and +20 dBm P1 dB. Current consumption at room temperature is 87 mA at 5 V supply. Linearity performance vs. frequency over the temperature range is depicted for WJA1500 in Figure 1.

Initially, the new family will include eight members, four in each series. According to Wahid Umerani, WJ Communications' director of strategic marketing, these new products offer an excellent mix of power gain, linearity, and supply current performance. For instance, he added, members offering gain variation can handle 15 dB or 20 dB variations, while those with current variation capability can reduce current consumption by 20% to 25%. However, when current consumption is reduced, the OIP3 performance is minimally impacted.

The 50 Ω internally matched amplifiers minimize the use of external components, thus simplifying system integration. Active bias circuitry is incorporated on-chip to minimize performance variations due to temperature.

The WJA MMIC amplifiers consists of Darlington pairs using a high-reliability InGaP/GaAs HBTs in class A configuration (Figure 2). The small signal broadband amplifiers are internally matched to 50 and only require dc-blocking capacitors and an inductive RF choke for operation. An internal active bias is designed to enable stable performance over a temperature range of -40 °C to +85 °C. It also eliminates the need for a dropping bias resistor and allows the device to be biased directly from a +5 V supply voltage.

Housed in compact SOT-89 surface-mount packages, the WJA10xx and WJA15xx amplifiers are RoHS-compliant. WJA10xx and WJA15xx series amplifiers are currently sampling with customers and are scheduled for production in July, said the manufacturer.
WJ Communications Inc.
(408) 577-6200
www.wj.com