20 August 2010


Avago’s 2300–4000MHz LNA completes range for cellular and LTE base-stations

Avago Technologies has launched the MGA-635P8 ultra-low-noise amplifier (LNA) for base-station (BTS) RF front-end design. The MGA-635P8 — which operates at frequencies of 2300–4000MHz — can be used in cellular applications such as the first stage of cellular base-station transceiver radio cards, tower mounted amplifiers (TMA), combiners, repeaters and remote/digital radio heads.

Together with the MGA-633P8 (450MHz up to 1.5GHz) and MGA-634P8 (1.5GHz up to 2.3GHz) — launched in February and July, respectively — Avago now has a complete family of production-ready high-linearity, ultra-low-noise amplifiers ready for high-volume GSM, TDS-CDMA and CDMA cellular infrastructure applications. All use Avago’s proprietary 0.25-micron, GaAs enhancement-mode pHEMT process for low noise and high linearity.

The wireless infrastructure industry must provide optimum coverage with the best signal quality in a crowded spectrum, says Avago. Receiver sensitivity is the most critical requirement in a BTS receiver's design. LNA selection, in particular the first-stage LNA, greatly affects the BTS receiver’s performance. Low noise figure is a key design goal. The MGA-635P8 has what is claimed to be a best-in-class noise figure (NF) of 0.56dB (0.75dB maximum) at 2.5GHz.

Another key design factor is linearity — specified by output third-order intercept (OIP3) — which affects the receiver's ability to distinguish between closely spaced wanted and spurious signals. At 2.5GHz and operating from single 5V power supply with a 56mA bias current (for low-power operation), the MGA-635P8 delivers OIP3 of 35.9dBm.

With built-in active bias circuitry, the MGA-635P8 operating current is adjustable, allowing tradeoffs between operating current and output linearity while maintaining an optimum noise figure, says Avago. BTS designers can hence 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. The MGA-635P8 is housed in an 8-lead, surface-mount quad flat no-lead plastic (QFN) package with a small 2.0mm x 2.0mm footprint and slim 0.75mm thickness. The operating temperature range is –25°C to +85°C.

In addition, common footprint, pin-out, package and matching network between the MGA-633P8, MGA-643P8 and MGA-653P8 simplifies PCB design and engineering.

Pricing of the MGA-653P8 is $2.31 each in 10,000 piece quantities.

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