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EME165
KIT DESCRIPTION
Please
Note: that all information including pictures on this web page
are copyright to Mini-Kits & must not be used on any other
web site.
The
circuit description below is for those that are wanting to know
if this Kit is suitable for their own application. The Kit comes
complete with detailed circuit & construction information,
including schematic & board overlay diagrams.
The
EME165 PC Board was designed to use a AD9954 14 bit 400MHz chip
but can be used with any of the AD995X series chips. The Kit is
for advanced constructors only that have experience in soldering
fine pitched components. This Kit may be a challenge for many
due to the very fine pitched Integrated circuits that are used
on the board. Many of the other conventional sized SMD components
are easily fitted. Do not attempt to build this Kit unless you
are confident that you can successfully complete it, as the cost
of repairs could be as much as a new Kit. When buying a full Kit,
Mini-Kits offers a service to fit the Integrated circuits at extra
cost.
The
board or Kit can be used with many of the DDS VFO projects, or
Software for the AD9954 that can be found on the WEB. The AD9954
is a +3.3v device & has been interfaced to a 16 Pin IDC I/O
header plug C1 using an ADG3300 +3.3v to +5v voltage translator
chip. These chips are much better than using voltage divider resistors,
& allow two way high speed bidirectional data to be sent between
the DDS & Micro controller.
The
16 Pin IDC I/O connector C1 has the following pin connections
available. The connections in blue
are +5v translated, & the yellow
are +3.3v direct to the DDS chip. As the ADG3300 chip only has
8 translators, only 8 data connections on the DDS can be translated
from +3.3v to +5v. It was decided to just use the common connections
that are normally used in AD9954 DDS projects. If you are going
to require the non translated +3.3v connections for your project,
then you may have to use another ADG3300 chip. Alternatively if
you are using low data rates you may be able to get away with
using simple 2 resistor voltage divider to drop the +5v from your
Micro controller to +3.3v. When using two AD9954 boards to provide
I/Q outputs, the sync out & sync in, & also clock out
& clock in can be directly connected as they are all +3.3v.
The HF-DDS software does not currently support the use of two
EME165 DDS boards for I/Q.
| RESET |
I/O UPDATE |
OSK |
SCLK |
SDO |
SDIO |
PS0 |
PS1 |
SYNC_CLK |
CS |
| +5V |
GND |
+12V |
GND |
NC |
GND |
NC |
NC |
SYNC IN |
SYNC OUT |
A
number of resistors, R1, R2, & R3 are used on the board as
links that may not be required for your application, but are required
when using the EME150 PIC Controller & HF-DDS software. See
the Kit schematic diagram for where the resistors are located.
The
DDS output uses a 175MHz 7th order elliptic Low Pass Filter, which
is used to reduce the aliases & quantization noise from the
DAC outputs. This allows us to use the maximum recommended output
frequency of 160MHz from the DDS for a 400MHz clock. A 1:1 Transformer
is used on the DAC outputs which has the benefit of reducing even
order harmonics, & produces +3dBm more output power. A Gali
amplifier with a gain of +25dB & a IP3 of +38dBm was chosen
as it was much lower cost compared to more complex amplifier designs.
The DAC current RSET has been adjusted to provide a very good
Spurious Free Dynamic Range, & drives the high gain Gali device
to around 1/2 its capable output power to produce a clean +10dBm
output. With reference to the fundamental output @ 0dBm, the 100MHz
clock is -45dB, 2nd Harmonic -36dBc, 3rd -54dBc, all other spurs
> -50dBc
The
PC Board uses plated through holes & separate analogue &
digital ground planes, & power supplies to reduce noise. The
AD9954 requires 3 power supply voltages so the board has two +1.8v
regulators for analogue & digital supplies, & a +3.3v
regulator for the digital I/O supply. All the chips & regulators
run quite cool compared to the older AD985X series DDS chips.
The
standard clock module that can be ordered for the Kit is a
100MHz 3.3v HY-Q QSMO-4213B 10ppm CMOS 5x7mm
module. The board can also be fitted with a standard 9x14mm
DIP package but it must be +3.3v, ( +5v types cannot be
used & many damage the AD9954 clock input ). Many CMOS clock
modules produce far too much output so a resistor is used on the
board to reduce the output so that the AD9954 is not overdriven.
The board also has a connector C3 that is suitable for feeding
in your own clock or for extraction of the clock to feed into
another AD9954 board.
Connector
C2 allows interfacing to the AD9954 internal high speed comparator.
The comparator can be used to produce a square wave clock from
the RF output suitable for switching mixers. Please refer to the
AD9954 data sheet.
EME165
KIT CONSTRUCTORS ALERT
There
are no alerts at this time. For any problems with your kit, please
refer to the kit faults & modification section below.
KIT
FAULTS & MODIFICATIONS
1/
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Friday
15th January 10