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Dual-channel logarithmic detector IC to measure and control RF signals

Norwood, Mass.—Chip maker Analog Devices Inc . (ADI) is pre-announcing availability of a RFIC (radio frequency IC) that comprises a dual detector/controller.

When it debuts in quantity later this year, the 6-stage demodulating device will be able to be used to closely measure and control gain across a transmitter and receiver signal path, letting it serve in AGC circuits, power-level control circuits, and even to measure forward and reverse VSWR (voltage standing wave ratio). The diagram here shows it throttling an RF power amplifier stage.

Slated for wireless infrastructure equipment designers, this IC will be able to simultaneously measure and monitor two input-signals with one package. Dubbed the ADL5519 , the RFIC will integrate two matched detectors on a single chip. That's expected to save considerable board area, and component cost, compared to conventional or discrete power measurement approaches.

Wide Frequency Range

In use, the ADL5519 will cover a very wide frequency range, extending from 1-MHz out to 10-GHz. That wide range will make the part suitable for use with all cellular standards (such as GSM, CDMA, W-CDMA , and TD-SCDMA ), as well as broadband wireless standards (such as IEEE-802.16, WiMAX, WiBro , and IEEE-802.11 WLAN ).

Obviously the device will also work in proprietary systems that operate in extended frequency bands, such as UNII 5.8-GHz . What's more, it should find application in other RF test and control applications.

Measurement And Control

The ADL5519 will essentially integrate two of Analog Devices's previously developed AD8317 log detector chips. In this integrated version, the two detectors will provide accurately-scaled and independent logarithmic outputs for both RF input channels.

The ADL5519 will also offer the benefits of ADI's AD8317 , with a response time of 0.8-ns (fall/rise). It will also exhibit a temperature stability spec of ±0.5-dB (over a 50-dB dynamic range).

A Difference Output

In addition to its two matched logarithmic output voltages, the ADL5519 will provide a difference output. It can be used to effectively measure the power gain or loss between two inputs.

With the difference output, the ADL5519 will be able to control gain across a transmitter or receiver signal chain, as each of the RFIC's two individual log detectors will be able to be set to measure inputs signals at different frequencies.

Finally, this nifty RFIC will also provide an accurately-scaled temperature output signal. The temperature sensor output will be capable of driving about 1.6-mA. The temperature scaling factor of the output voltage is approximately 2-mV/°C. The typical absolute voltage (at 25°C) is about 620-mV.

Supply and Package

The ADL5519 will operate over a supply voltage range of 3-V to 5-V, with typical current demand of 56-mA when enabled. Current drops to 400-µA when disabled.

The device will be packaged in a space-saving 4-mm x 4-mm 24-lead LFCSP (lead-frame chip-scale package).

Price And Availability

The ADL5519 is in sampling now, with volume production scheduled for October. It will be priced at less than $5 a pop (in 1,000-piece quantities).

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

Analog Devices, Inc., 3 Technology Way, Norwood, MA 02062. Phone: 781-329-4700 or 800-ANALOGD. Fax: 781-461-3113.

Analog Devices , 781-329-4700, www.analog.com

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