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Dual RF power detector chips work to 11-GHz

Milpitas, Calif.—The fabs at Linear Technology Corp (LTC) are dishing up dual-channel RF detector chips that work out to 11-GHz. LTC's LTC5533 can therefore be used to measure RF power in multi-band WiFi, WiMAX and other radio applications. As the curve indicates, they develop a nonlinear output voltage that’s proportional to RF power.

These low cost devices can measure power over a range extending from -32-dBm to +12-dBm. If need be, you can even used them, at reduced performance, above 11-GHz. The diagram below shows a typical application in a dual-band cellphone with PA (power amplifier) level control.

Each LTC5533 package contains two RF detector dice forming two independent RF detector channels. Channel functions include an internal frequency-compensated buffer amp, with gain set to 2x. The output buffer amplifiers are capable of supplying 4-mA into loads.

You also get an RF Schottky diode peak detector and level-shift amplifier to convert RF input signals to low frequency. There are also delay circuits to avoid voltage transients at VOUT when powering up. Finally, the LTC5533 has both shutdown and starting voltage adjustment capabilities.

Operable down to 300-MHz, surface-mount LTC5533s can support detection of multiple frequencies in one package, as needed for multi-band applications. In use, these power-managed ICs also draw only about 500-µA/detector, and can operate from VCC supplies from 2.7-V to 6-V. A power saving shutdown mode reduces current draw to less than 2-µA/channel.

In addition to its diode peak detectors, the LTC5533s also contain temperature compensation circuitry that ensures stable and accurate measurements over full temperature range. These chips also exhibit 40-dB of dynamic range, and 45-dB channel-to-channel isolation.

LTC5533s are available from stock and are priced at about $3.20 each in 1,000-piece quantities.

Click here for a datasheet (in Adobe Acrobat .PDF format).

For more details contact Linear Technology Corp., 1630 McCarthy Boulevard, Milpitas, Calif. 95035-7417. Phone: 800-454-6327.

Linear Technology , 800-454-6327, www.linear.com

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