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© Analog Devices, Inc., 2002
Evaluation Board for AD9874
FUNCTIONAL BLOCK DIAGRAM
CLKIN
IFIN
LO_IN
P1
AD9874
TB1
TB4
TB3
U12
U13
IDT
FIFO
XILINX
FPGA
J6
J3
J1
LO VCO
MODULE INTERFACE
VDIRECT
MIXER OUT
TB2
EPROM
HEADER
IF MATCHING
N
ETWORK
JP1–9
VREG
JP22
JP23
JP15
JP18
CRYSTAL
OSC.
JP24
JP25
SW2
SW1
LED
FREF
J2
J5
AD9874 REVC
ANALOG
DEVICES
EVAL-AD9874EB
Windows is a registered trademark of Microsoft Corp.
LabVIEW is a trademark of National Instruments.
GENERAL DESCRIPTION
The evaluation board for the AD9874 and its accompanying
software provide a simple means to evaluate this highly inte-
grated IC. The AD9874 is a general-purpose IF subsystem that
digitizes a low level 10 MHz–300 MHz IF input with signal
bandwidths ranging from 6.8 kHz to 270 kHz. The signal chain
within the IC consists of a low noise amplifier, a mixer, a vari-
able gain amplifier, a band-pass
-
analog-to-digital converter,
and a decimation filter with programmable decimation factor.
Auxiliary blocks include clock and LO synthesizers as well as a
serial peripheral interface (SPI) port.
The functional block diagram shows the major blocks of the evalua-
tion board. The evaluation board is designed to be flexible, allowing
the user to configure it for different potential applications. The
power supply distribution block provides filtered, adjustable volt-
ages to the various supply pins of the AD9874.
In the IF input
signal path, component pads are available to implement different
IF impedance matching networks. The LO and CLK signals can
be externally applied or internally derived from a user-supplied
VCO module interface daughter board. The reference for the
on-chip LO and CLK synthesizers can be applied via the external
FREF input or an on-board crystal oscillator.
The evaluation board is designed to interface to a PC via a National
Instruments NI 6533 series digital IO card. A XILINX FPGA
formats the data between the AD9874 and digital I/O board.
Software, developed using National Instruments’ LabVIEW™
and provided as Windows
®
executable programs, is supplied for
the configuration of the SPI port registers and analysis of the
AD9874’s output data. This software provides a convenient
graphical user interface, allowing easy access to the various
SPI port configuration registers along with real-time frequency
and time domain analysis of its output data.
