GENERAL DESCRIPTION
The AD8347 is a broadband direct quadrature demodulator with RF and baseband automatic gain control (AGC) amplifiers. It is suitable for use in many communications receivers, performing
quadrature demodulation directly to baseband frequencies. The input frequency range is 800 MHz to 2.7 GHz. The outputs can be connected directly to popular A-to-D converters such as the
AD9201and AD9283. The RF input signal goes through two stages of variable gain amplifiers prior to two Gilbert-cell mixers. The LO quadrature phase splitter employs polyphase filters to achieve high quadrature accuracy and amplitude balance over the entire operating frequency range. Separate I and Q channel variable gain amplifiers follow the baseband outputs of the mixers. The
RF and baseband amplifiers together provide 69.5 dB of gain control. A precision control circuit sets the linear-in-dB RF gain response to the gain control voltage.

FEATURES
Integrated RF and baseband AGC amplifiers
Quadrature phase accuracy 1° typ
I/Q amplitude balance 0.3 dB typ
Third-order intercept (IIP3) +11.5 dBm @ min gain
Noise figure 11 dB @ max gain
AGC range 69.5 dB
Baseband level control circuit
Low LO drive −8 dBm
ADC-compatible I/Q outputs
Single supply 2.7 V to 5.5 V
Power-down mode
28-lead TSSOP package

APPLICATIONS
Cellular base stations
Radio links
Wireless local loop
IF broadband demodulators
RF instrumentation
Satellite modems