50 MHz TO 525 MHz Quadrature Demodulator with Fractional-N PLL and VCO
The ADRF6806 is a high dynamic range IQ demodulator with integrated PLL and VCO. The fractional-N PLL/synthesizer generates a frequency in the range of 2.8 GHz to 4.2 GHz. A programmable quadrature divider (divide ratio = 4 to 80) divides the output frequency of the VCO down to the required local oscillator (LO) frequency to drive the mixers in quadrature. Additionally, an output divider (divide ratio = 4 to 8) generates a divided-down VCO signal for external use.
The PLL reference input is supported from 10 MHz to 160 MHz. The phase detector output controls a charge pump whose output is integrated in an off-chip loop filter. The loop filter output is then applied to an integrated VCO.
The IQ demodulator mixes the differential RF input with the complex LO derived from the quadrature divider. The differential I and Q output paths have excellent quadrature accuracy and can handle baseband signaling or complex IF up to 120 MHz.
A reduced power mode of operation is also provided by programming the serial interface registers to reduce current consumption, with slightly degraded input linearity and output current drive.
The ADRF6806 is fabricated using an advanced silicon-germanium BiCMOS process. It is available in a 40-lead, exposed-paddle, RoHS-compliant, 6 mm × 6 mm LFCSP package. Performance is specified over the −40°C to +85°C temperature range.
- QAM/QPSK RF/IF demodulators
- Cellular W-CDMA/CDMA/CDMA2000
- Microwave point-to-(multi)point radios
- Broadband wireless and WiMAX
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This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
The ADRF6806-EVALZ is a full featured evaluation board designed to allow the user to easily evaluate all features of the ADRF6806. The evaluation board provides a USB interface for easy VCO frequency programming. RF input and baseband output SMA connections with single ended setups are featured. There is an option of fully differential baseband signaling on the output at the card edge if user desires. Access to the +3.3 V/209 mA supply and +5 V/86 mA supply is achieved with clip leads to the VCC2 and GND2 testpoints and the VCC and GND testpoint respectively; the supplies have a range of +3.135 V to +3.465 V and +4.75 V to +5.25 V, respectively. The ADRF6806-EVALZ board is a 4 layer board made of Rogers material. Setting the VCO frequency (and other functions) is achieved via the SPI port which can be programmed via the ADRF6806 USB software provided on the ADI webpage.
Recommended Baseband Driver Amplifiers
- For a digital programmable VGA , we recommend the AD8366 .
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- For selectable gains of 1, 2 or 3 , we recommend the ADA4950-1 or the ADA4950-2 .
- For variable gain and programmable baseband filters , we recommend the ADRF6510 or the ADRF6516 .
Recommended Dual Analog-to-Digital Converters
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- For 12-bit performance, low power, low cost and ease of use , we recommend the AD9231 .
- For 14-bit performance, low power and high sampling rate , we recommend the AD9258 or the AD9251 .