| ??? 03/09/06 17:46 Read: times |
#111771 - Seperate Analog and Digital Supply Responding to: ???'s previous message |
I've used several of the Analog devices DDS Synthesizers and am currently using an AD9833 for a project here at the city. I agree with the others regarding the groung plane. More importantly though, the AD9835 REQUIRES a seperate 5V supply for thed Analog and Digital sections of the device, or you will see exactly what you are seeing. You are getting noise generated by the micro on the output of the device. Your ground plane needs to be configured as much as a single point "Star" type ground as possible to minimize noise. This is all discussed and stressed in the data sheet. The resulting noise on the sinewave translates to a much higher noise floor on a receiver so that the performance of the receiver is sacrificed. Good luck with your project.
73's Trev - K6ESE |
| Topic | Author | Date |
| AD9835 noise problem | 01/01/70 00:00 | |
| noise | 01/01/70 00:00 | |
| Recommendations | 01/01/70 00:00 | |
| quick fix? | 01/01/70 00:00 | |
| Maybe | 01/01/70 00:00 | |
| Transmission lines | 01/01/70 00:00 | |
| 5MHz? | 01/01/70 00:00 | |
| Spectrum analyser | 01/01/70 00:00 | |
| It's ground noise | 01/01/70 00:00 | |
| ground noise and groundhogs | 01/01/70 00:00 | |
| Harmonics as well | 01/01/70 00:00 | |
| comments | 01/01/70 00:00 | |
| Why separate the analog & digital gnds? | 01/01/70 00:00 | |
| Splitting the ground plane | 01/01/70 00:00 | |
| Evaluation board | 01/01/70 00:00 | |
| thin ground? | 01/01/70 00:00 | |
| that is why you use star | 01/01/70 00:00 | |
| Ground wire in parallel | 01/01/70 00:00 | |
| and a twisted pair? | 01/01/70 00:00 | |
| Would do! | 01/01/70 00:00 | |
| does not exist, Jan if you used twisted | 01/01/70 00:00 | |
| The clock signal? | 01/01/70 00:00 | |
| oh well | 01/01/70 00:00 | |
| Indeed | 01/01/70 00:00 | |
| is there a way... | 01/01/70 00:00 | |
| Hardly | 01/01/70 00:00 | |
| unfortunately not | 01/01/70 00:00 | |
| twisted pair | 01/01/70 00:00 | |
| is that not obvious | 01/01/70 00:00 | |
| No ground traces, but patches | 01/01/70 00:00 | |
| the bane of many | 01/01/70 00:00 | |
| Why 1 or 2 layers | 01/01/70 00:00 | |
| it's nice! | 01/01/70 00:00 | |
| No Secrets | 01/01/70 00:00 | |
| DALO 2M professional | 01/01/70 00:00 | |
| UV ink Problem | 01/01/70 00:00 | |
| Mixed method? | 01/01/70 00:00 | |
| No Need for DALO | 01/01/70 00:00 | |
| CE | 01/01/70 00:00 | |
| Single step mode | 01/01/70 00:00 | |
| If you want... | 01/01/70 00:00 | |
| mmm | 01/01/70 00:00 | |
| Dreaming | 01/01/70 00:00 | |
| LAYOUT | 01/01/70 00:00 | |
| 100nF caps | 01/01/70 00:00 | |
| 100nF ? | 01/01/70 00:00 | |
| ok | 01/01/70 00:00 | |
| Some checks | 01/01/70 00:00 | |
| It's my daily job! | 01/01/70 00:00 | |
| Unfortunately, no | 01/01/70 00:00 | |
| simulate double-layer | 01/01/70 00:00 | |
| Seperate Analog and Digital Supply | 01/01/70 00:00 | |
| RLC-filters don't help? | 01/01/70 00:00 | |
| separate | 01/01/70 00:00 | |
| And... | 01/01/70 00:00 | |
| Seperate Supplies | 01/01/70 00:00 | |
| Evaluation board | 01/01/70 00:00 | |
| No not that one... | 01/01/70 00:00 | |
| Curly | 01/01/70 00:00 | |
| OT: Hair | 01/01/70 00:00 | |
| lets have pictures | 01/01/70 00:00 | |
| No no... | 01/01/70 00:00 | |
| http://www.k6ese.com/Mar_Vista_Shack.htm | 01/01/70 00:00 | |
| but it is relevant | 01/01/70 00:00 | |
| No wonder... | 01/01/70 00:00 | |
| waveforms | 01/01/70 00:00 | |
| Link to DDS page | 01/01/70 00:00 | |
| Add the second stage... | 01/01/70 00:00 | |
| Filter components | 01/01/70 00:00 | |
| clock | 01/01/70 00:00 | |
| What clock | 01/01/70 00:00 | |
| ? | 01/01/70 00:00 | |
| Sampling theorem | 01/01/70 00:00 | |
| But... | 01/01/70 00:00 | |
| Can't find it now | 01/01/70 00:00 | |
| Ground of probe? | 01/01/70 00:00 | |
| even better | 01/01/70 00:00 | |
| Good trick! | 01/01/70 00:00 | |
| same point | 01/01/70 00:00 | |
| Both | 01/01/70 00:00 | |
| I feel strong now! | 01/01/70 00:00 | |
| Funny! | 01/01/70 00:00 | |
| Depends... | 01/01/70 00:00 | |
| Oh Dear | 01/01/70 00:00 | |
| NO analog outputs | 01/01/70 00:00 | |
| since there is no schematics presented | 01/01/70 00:00 | |
| Publishing failed | 01/01/70 00:00 | |
| then give a link to an ORCAD drawing | 01/01/70 00:00 | |
| Schematics | 01/01/70 00:00 | |
| corrections | 01/01/70 00:00 | |
| Big test | 01/01/70 00:00 | |
| Try This Schematic... | 01/01/70 00:00 | |
| one more problem | 01/01/70 00:00 | |
| I miss the second 300R resistor | 01/01/70 00:00 | |
| Terminating Resistor. | 01/01/70 00:00 | |
| Answers | 01/01/70 00:00 | |
| University of Kai | 01/01/70 00:00 | |
| Keep us informed... | 01/01/70 00:00 | |
| of course | 01/01/70 00:00 | |
| Update | 01/01/70 00:00 | |
| Eager to know | 01/01/70 00:00 | |
| Me too | 01/01/70 00:00 | |
| Autoreload | 01/01/70 00:00 | |
| Current source output | 01/01/70 00:00 | |
| Electronic World Feb 06 | 01/01/70 00:00 | |
| Superb! | 01/01/70 00:00 | |
| No surprise | 01/01/70 00:00 | |
| AD9835 Cycles | 01/01/70 00:00 | |
| Solid Ground Plane Update!!!!! | 01/01/70 00:00 | |
| Very nice results! | 01/01/70 00:00 | |
| Low frequency | 01/01/70 00:00 | |
| SLIGHt correction | 01/01/70 00:00 | |
| OPA27? | 01/01/70 00:00 | |
| Cross talk on PCB tracks | 01/01/70 00:00 | |
| Have a look at this plot | 01/01/70 00:00 | |
| Interesting question | 01/01/70 00:00 | |
further interesting question | 01/01/70 00:00 |