15 July 2010


Avago’s 1500–2300MHz LNA offers 0.44dB noise figure and 36dBm OIP3 linearity for cellular infrastructure

Analog component supplier Avago Technologies has expanded its series of low-noise amplifiers (LNAs) to cover new GSM, TDS-CDMA and CDMA cellular infrastructure applications (e.g. transceiver radio cards, tower-mounted amplifiers, combiners, repeaters and remote/digital radio heads) by announcing availability of its 1500–2300MHz MGA-634P8 LNA for base-station (BTS) RF front-end design.

For wireless infrastructure to provide optimum coverage with the best signal quality in a crowded spectrum, receiver sensitivity is the most critical requirement in a base-station’s receiver design, says Avago. LNA selection, particularly in the first stage of the amplifier chain, greatly affects the BTS receiver’s performance. Low noise figure is a key design goal, and another key design requirement is high linearity, which affects the receiver’s ability to distinguish between closely spaced wanted and spurious signals.

At 1900MHz and operating from a single 5V power supply with a 48mA bias current, Avago’s proprietary 0.25-micron GaAs enhancement-mode pseudomorphic high-electron-mobility transistor (pHEMT) process technology gives the MGA-634P8 what is claimed to be a best-in-class low noise figure (NF) of 0.48dB (0.69dB maximum) and a high output third-order intercept (OIP3) linearity of 36dBm. The low NF and high OIP3 gives designers more margin for the BTS receiver path than available from previous amplifiers, says Avago. The added performance is achieved with very low quiescent power of about 240mW. The operating temperature range is –25°C to +85°C.

With built-in active bias circuitry, the MGA-634P8's operating current is adjustable, allowing tradeoffs between operating current and output linearity while maintaining an optimum noise figure. BTS designers can therefore meet various design needs and regional requirements with the same LNA.

Also, since more communication channels must now fit onto a transmit/receive card, PCB real estate has become a key design challenge for BTS engineers, says Avago. The MGA-634P8 is housed in an 8-lead, surface-mount quad flat no-lead plastic (QFN) package with a small 4mm2 footprint and slim 0.75mm thickness.

In addition, the MGA-634P8 LNA shares the same package footprint, pinout and external matching network of the existing 900MHz MGA-633P8 LNA. A common PCB design can therefore be used for BTS RF front-end designs that operate in different frequency bands, allowing different geographic markets to be served by one basic PCB design.

The MGA-634P8 is priced at $2.31 each in 10,000 piece quantities.

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