AD9850 / AD9851 DDS Module
The Construction notes, programming details and updated firmare for the 16F628 PIC are here.
AD9850_51_PIC.ZIP
Please note ........
Way back in November 2000 I published a design for a synthesizer module based around the
(now rather long-in-the-tooth) AD9850 DDS chip. The PCBs or complete modules were, in those days, marketed by a small company
HF Instruments, a then fresh start up run by a friend of mine , G4KZY.
The module only had limited popularity, and after the first run we discontinued it; HF Instruments merged, changed hands,
moved on to bigger things, and I had, by that time moved on to the AD9852 chip (See
Projects ) and no longer bothered with that older design
However, that chip and the AD9851 (the faster 180MHz clocked version with its X6 clock PLL) are still around, are relatively low cost,
and I've recently had a few enquiries about the module.
It has also had a bit of a rebirth for microwavers as part of beacon sources and in locking
crystal oscillators. See LckdSrcs.pdf
I have no plans to have any more boards made up - it wasn't even a particularly good layout - but is simple enough to roll your
own if you can make PCBs with a resolution good enough for TSSOP ICS with their 0.6mm pad spacing
If you want any other version of the layout, just ask and I'll see what is possible
There is a missing track on the PCB, the two +Vdd pins on the left hand side of the IC, while having their decoupling capacitors in place,
are not connected to +5V !!!!!!!!!!!
This doesn't stop the device working as the pins are connected internally to the other Vdd pins. But if
you make ANY attempt to draw current externally from this point, eg to power a clock oscillator module, its current has to be passed via
the internal IC tracks which is likely to destroy them. Been there, done that :-(
The wire link needed is shown on the layout diagam.