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6GHz Matched Dual RMS Detectors Enable Accurate VSWR Measurements
MILPITAS, CA - September 9, 2010 - Linear Technology introduces
the LTC5583, a 40MHz to 6GHz dual channel,
matched RMS power detector, offering over 55dB isolation at
2.14GHz. In RF power amplifier (PA) applications, the LTC5583
provides a simple solution for accurately measuring forward power,
reverse power, and voltage standing wave ratio (VSWR). The device
comprises a pair of 60dB dynamic range RMS detectors that are
matched to 1.25dB. This provides accurate RF power measurement of
high crest-factor signals such as those used in LTE, WiMAX, W-CDMA,
TD-SCDMA and CDMA2000 3G or 4G basestations and other
high-performance radios employing complex modulation waveforms.
Each channel can detect signals accurately from as small as -58dBm
to 2dBm, in a log-linear response with a typical linearity of
better than +/-0.5dB covering all cellular frequency bands. At
higher frequencies, the device is capable of providing 47dB of
useful dynamic range up to 6GHz. Unique to the LTC5583, each
detector simultaneously tracks the envelope of the modulated input
waveform, providing on-chip capability to measure both peak and
average signal power.
The LTC5583 has best-in-class channel-to-channel isolation of over
55dB at 2.14GHz, when driven differentially. Unlike other
detectors, the LTC5583 can operate single-ended for RF input
frequencies up to 2.14GHz, requiring no external balun
transformers. This configuration greatly reduces costs without
trading off dynamic range and provides isolation better than 40dB.
An integrated amplifier measures the difference between the two
detector outputs. For applications where one RF input is measuring
the forward power and the other the reflected power, the difference
output provides real time VSWR results. The two matched detectors
are also useful in applications such as monitoring and controlling
RF amplifier stage gain. The LTC5583’s matching and isolation
performance minimize calibration requirements, thus simplifying
designs and reducing costs.
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The detectors exhibit outstanding temperature performance. Each
detector maintains accuracy of +/-1dB error over a 53dB dynamic
range over its specified operating temperature range of -40°C to
85°C. This enables the LTC5583 to be used in rugged environments
such as Remote Radio Units (RRUs) or Outdoor Units (ODUs) deployed
on cellular towers. Moreover, the device has on-chip provisions for
first- and second-order temperature compensation which enable easy
calibration for improved temperature performance. |
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Summary of Features: LTC5583
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6GHz RMS Power Detector with Digital
Output |
