Analog Devices Inc.

The AD9864 is a general-purpose IF subsystem that digitizes alow level, 10 MHz to 300 MHz IF input with a signal bandwidthranging from 6.8 kHz to 270 kHz. The signal chain of the AD9864consists of a low noise amplifier (LNA), a mixer, a band-pass ?-?analog-to-digital converter (ADC), and a decimation filter withprogrammable decimation factor. An automatic gain control(AGC) circuit gives the AD9864 12 dB of continuous gainadjustment. Auxiliary blocks include both clock and localoscillator (LO) synthesizers.The high dynamic range of the AD9864 and inherent antialiasingprovided by the band-pass ?-? converter allow the device to copewith blocking signals up to 95 dB stronger than the desired signal.This attribute often reduces the cost of a radio by reducing IFfiltering requirements. Also, it enables multimode radios of varyingchannel bandwidths, allowing the IF filter to be specified for thelargest channel bandwidth.The SPI port programs numerous parameters of the AD9864,allowing the device to be optimized for any given application.Programmable parameters include synthesizer divide ratios, AGCattenuation and attack/decay time, received signal strength level,decimation factor, output data format, 16 dB attenuator, and theselected bias currents.The AD9864 is available in a 48-lead LFCSP package and operatesfrom a single 2.7 V to 3.6 V supply. The total power consumptionis typically 56 mW and a power-down mode is provided viaserial interfacing.APPLICATIONS Multimode narrow-band radio products Analog/digital UHF/VHF FDMA receivers TETRA, APCO25, GSM/EDGE Portable and mobile radio products SATCOM terminals

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