Wireless Systems Design

High-Speed Wi-Fi Welcomes Integration

Orthogonal-frequency-division-multiplexing (OFDM) signals suffer problems because of the signals' very high and inconsistent peak-to-average power ratios. Usually, resolving these issues requires a backoff of power or very highly linear power amplifiers (PAs). But a backoff of power reduces performance, while very highly linear PAs can be power hungry. To put these OFDM-signal challenges to rest, SiGe Semiconductor has released a new power amplifier.

Dubbed the RangeCharger SE2535, this PA includes an integrated power detector. To accommodate the peak-to-average power ratio, the detector adjusts the operating point. The power consumption can then be reduced accordingly at any given time. This approach saves power while maintaining performance.

This low-current device consumes only 160 mA for +18-dBm output power. As a result, the SE2535 promises to reduce power consumption to levels that support high-speed wireless access in portable applications. The PA also boasts very high integration. In a standard QFN package that measures just 4 × 4 × 0.9 mm, this linear, three-stage, 27-dBm PA incorporates the power detector and all of the analog biasing and matching circuitry.

By integrating the analog functions, the SE2535 claims to minimize external-component requirements compared to alternative solutions. It also eliminates the need for external bandpass filtering. These features result in a reduced bill of materials (BOM) and design-resource savings. They also allow manufacturers to deliver Wi-Fi systems with reduced cost and smaller form factors.

In addition, the SE2535 is capable of achieving an error vector magnitude (EVM) of less than 2.5% at 18 dBm. This low EVM translates into improved packet-error rates for optimal data throughput and performance over the full transmission range.

The SE2535 is available now. In quantities of 100,000 units, it is priced at $1.75.

SiGe Semiconductor, Inc.
2680 Queensview Dr., Ottawa, Ontario, Canada K2B 8J9; (613) 820-9244, FAX: (613) 820-4933, www.sige.com.

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