Low-noise amplifier for cellular applications

Avago Technologies has launched its MGA-635P8 ultra-low-noise amplifier (LNA) for base station (BTS) RF front-end design in a variety of cellular infrastructure applications.

These include first stage of cellular base station transceiver radio cards, tower-mounted amplifiers (TMA), combiners, repeaters and remote/digital radio heads.

The MGA-635P8 LNA adds to Avago's high-linearity, ULN amplifier series, which includes the MGA-633P8 (450MHz up to 1.5GHz) and MGA-634P8 (1.5GHz up to 2.3GHz).

With the addition of the 2,300-4,000MHz MGA-635P8, Avago can offer a complete family of production-ready LNAs ready for high-volume GSM, TDS-CDMA and CDMA cellular infrastructure applications.

The wireless infrastructure industry must provide optimum coverage with the best signal quality in a crowded spectrum.

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 said to be a key design goal.

The MGA-635P8 has a noise figure of 0.56dB, 0.75dB maximum, at 2,500MHz.

Another important design factor is linearity, which affects the receiver's ability to distinguish between closely spaced wanted and spurious signals.

Output third-order intercept, OIP3, is used to specify linearity.

At 2,500MHz and operating from 5V with a 56mA bias current, Avago's MGA-635P8 delivers an OIP3 performance of 35.9dBm.

With built-in active bias circuitry, the MGA-635P8 operating current is adjustable.

This allows designers to make trade-offs between operating current and output linearity while maintaining an optimum noise figure.

BTS designers can meet various design needs and regional requirements with the same Avago LNA.

Since more communication channels must now fit onto a transmit/receive card, PCB real estate has become a key design challenge for BTS engineers.

The MGA-635P8 is housed in a quad flat no-lead plastic (QFN) package with a 2 x 2mm footprint and 0.75mm thickness.

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