ADRF6801 750 MHz TO 1150 MHz Quadrature Demodulator with Fractional-N PLL and VCO

The ADRF6801 is a high dynamic range IQ demodulator with integrated PLL and VCO. The fractional-N PLL/synthesizer generates a frequency in the range of 3.0 GHz to 4.6 GHz. A divide-by-4 quadrature divider divides the output frequency of the VCO down to the required local oscillator (LO) frequency to drive the mixers in quadrature. Additionally, an output buffer can be enabled that generates an fVCO/2 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.

The ADRF6801 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.

Applications

QAM/QPSK RF/IF demodulators
Cellular W-CDMA/CDMA/CDMA2000
Microwave point-to-(multi)point radios
Broadband wireless and WiMAX

Features and Benefits

IQ demodulator with integrated fractional-N PLL
LO frequency range: 750 MHz to 1150 MHz
Input P1dB: 12.5 dBm
Input IP3: 25 dBm
Noise figure (DSB): 14.3 dB
Voltage conversion gain: 5.1 dB

Quadrature demodulation accuracy
Phase accuracy: 0.3°
Amplitude accuracy: 0.05 dB
Baseband demodulation: 275 MHz, 3 dB bandwidth
SPI serial interface for PLL programming
40-lead, 6 mm × 6 mm LFCSP