The AD9864 is a general-purpose IF subsystem that digitizes a
low level, 10 MHz to 300 MHz IF input with a signal bandwidth
ranging from 6.8 kHz to 270 kHz. The signal chain of the AD9864
consists of a low noise amplifier (LNA), a mixer, a band-pass Σ-∆
analog-to-digital converter (ADC), and a decimation filter with
programmable decimation factor. An automatic gain control
(AGC) circuit gives the AD9864 12 dB of continuous gain
adjustment. Auxiliary blocks include both clock and local
oscillator (LO) synthesizers.
The high dynamic range of the AD9864 and inherent antialiasing
provided by the band-pass Σ-∆ converter allow the device to cope
with blocking signals up to 95 dB stronger than the desired signal.
This attribute often reduces the cost of a radio by reducing IF
filtering requirements. Also, it enables multimode radios of varying
channel bandwidths, allowing the IF filter to be specified for the
largest 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, AGC
attenuation and attack/decay time, received signal strength level,
decimation factor, output data format, 16 dB attenuator, and the
selected bias currents.
The AD9864 is available in a 48-lead LFCSP package and operates
from a single 2.7 V to 3.6 V supply. The total power consumption
is typically 56 mW and a power-down mode is provided via
serial interfacing.
Applications
- Multimode narrow-band radio products
Analog/digital UHF/VHF FDMA receivers
TETRA, APCO25, GSM/EDGE
- Portable and mobile radio products
- SATCOM terminals
