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RMS detector delivers accurate RF power measurements

Posted: 20 Aug 2010 ?? ?Print Version ?Bookmark and Share

Keywords:RMS detector? RF power measurement? radios? FPGA-based systems?

Linear Technology has announced the release of its LTC5587, a 40dB dynamic range 6GHz RMS detector integrated with a high sampling rate 12-bit serial A/D converter. The digital output RMS RF detector gives +/-1dB measurement accuracy of high crest-factor signals, independent of the modulation used.

It can operate over a wide frequency range from 10MHz to 6GHz. Its integrated 12-bit ADC captures and digitizes the detector measurement at a rate of up to 500k samples/second and delivers the data via a bit stream over a serial SPI port. The detector functions with single-ended input and requires no external balun transformer. It comes in a 3mm x 3mm DFN package.

The LTC5587 maintains +/- 1dB accuracy in a 40dB dynamic range over a temperature range of -40 degrees C to 85 degrees C, giving efficient performance. Combined with a 12-bit A/D converter, the device offers a 0.014dB per bit measurement resolution. The detector's low power consumption is ideal for applications such as cellular base stations, picocells, and femtocells supporting all standards including LTE, W-CDMA, TD-SCDMA, CDMA/2k, GSM/EDGE and WiMAX. Other possible applications include: MIMO radios, repeaters, point-to-point microwave links, military radios with complex modulation, remote power measurements, and portable test and measurement instruments. The detector is particularly useful in FPGA-based systems wherein no A/D converters are available.

The LTC5587 draws power from a single 3.3V supply. In sampling mode, its total operating current is 3mA, using only 10mW of power. Its consumption is further reduced into half when the ADC is at idle mode, making it applicable for battery powered or portable remote RF measurement systems. Furthermore, the device also has shutdown capability, drawing less than 10uA supply current when disabled.

The key features of the LTC5587 ar: operating frequency range of 10MHz to 6GHz; log-linear dynamic range (modulated signals) at 880MHz = 40dB, at 2.14GHz = 37dB, at 3.5GHz = 35dB; accurate RF measurement range of -34dBm to 6dBm; accuracy over temperature (-40 degrees C to +85 degrees C) +/- 1dB; integrated 12-Bit ADC 500ksps sampling rate; SPI/MICROWIRE Serial I/O; low power consumption at 10mW (3.3V, 3mA); single-ended RF input, no external transformer; fast acquisition time, rise = 2us, fall = 8us; small package at 3mm x 3mm DFN.

The LTC5587 is available from stock, priced starts at $5.17 each in 1,000-unit orders.

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