Building a circuit which involves with a AD9854 DDS

  • Thread starter Thread starter kent
  • Start date Start date
  • Tags Tags
    Building Circuit
Click For Summary

Discussion Overview

The discussion revolves around building a circuit using the AD9854 Direct Digital Synthesis (DDS) chip, specifically focusing on generating a frequency-controllable sine wave. Participants explore the requirements for the master clock supply, which is stated to need to be around 200MHz, and discuss potential oscillator options.

Discussion Character

  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant expresses uncertainty about the availability of a crystal oscillator or CMOS programmable oscillator that can provide a 200MHz master clock for the AD9854 DDS chip.
  • Another participant points out that the datasheet indicates a minimum external clock frequency of 15MHz, suggesting that this frequency is available in canned oscillator form.
  • A different participant mentions that the internal clock of the AD9854 requires at least 20MHz, but with a built-in PLL multiplier, the external clock can be as low as 5MHz if configured correctly.
  • There is a reiteration that the internal clock can run lower than 15MHz while still achieving a 300MHz internal clock when the appropriate settings are applied.

Areas of Agreement / Disagreement

Participants present multiple viewpoints regarding the clock frequency requirements and oscillator options, with no consensus reached on the best approach to achieve the desired clock frequency for the AD9854 chip.

Contextual Notes

Some assumptions about the capabilities of the AD9854 chip and the configurations required for the PLL multiplier are discussed, but these are not fully resolved within the conversation.

kent
Messages
13
Reaction score
0
Hi Guys..

I am try building a circuit which involves with a AD9854 DDS(Direct Digital Synthesis) chip to generate a frequency controlable sine wave for me...

The problem for me is that the Master clock supply for the chip need to be around 200MHz...I don't know whether there is any crystal oscillator that can perform this function...or maybe there are some CMOS programmable oscillator chips that can do the trick for me...?

Here is the link of the chip:
http://www.analog.com/en/prod/0,2877,AD9854,00.html

Thank you guys for ur help!
 
Engineering news on Phys.org
Sorry guys...wrong link...

Here is the correct one:
http://www.analog.com/en/prod/0,,770_843_AD9854,00.html
 
Last edited by a moderator:
kent said:
Sorry guys...wrong link...

Here is the correct one:
http://www.analog.com/en/prod/0,,770_843_AD9854,00.html

On page 30 of that datasheet, it says that you can put in as little as 15MHz, which is definitely available in canned oscillator form. I'd stay away from messing around with anything over about 50MHz, unless you are making your own PCBs and understand stripline transmission line techniques.
 
Last edited by a moderator:
kent said:
The problem for me is that the Master clock supply for the chip need to be around 200MHz...

HAHA! I made a lot of the plots that are in this datasheet when I was a co-op at Analog Devices ~10 years ago!

The internal clock on the AD9854 needs to be at least 20Mhz. There's a built in PLL multiplier, so the external clock source that you supply can be as low as 5Mhz. You just have to enable the multiplier, and set the bits appropriately (see pages 30-31).

On page 30 of that datasheet, it says that you can put in as little as 15MHz
as low as 15Mhz and still achieve 300Mhz internal clock. The internal clock can run lower than this as well.
 
Thanks asynchronous13, and welcome to the PF. It must have been way cool to work at AD as a co-op! Where are you now?
 
i ran 100's of these parts through FFT's for characterization while i was there. Analog Devices was a great place to work, but they didn't give me enough to do as a co-op, so i ended doing stuff like designing/building guitar distortion pedals for personal use :-)

10 yrs in summary: BS in EE from U of Tennessee -> Harris Corporation in FL (worked on international space station and Comanche helicopter) -> France for grad school, got a french EE degree -> masters in EE from GaTech (DSP) -> currently in Atlanta at GaTech working on PhD in unmanned aerial vehicles
 
Last edited:

Similar threads

I/Q (Inphase and quadrature) demodulation circuit
  • · Replies 1 ·
Replies
1
Views
10K
How can I design an output filter for a DDS generator using the AD9834 IC?
  • · Replies 11 ·
Replies
11
Views
11K
Need Help in Transformers and Complex Circuit handling
  • · Replies 1 ·
Replies
1
Views
2K
Mathematica This Week's Finds in Mathematical Physics (Week 236)
  • · Replies 7 ·
Replies
7
Views
4K
Mathematica This Week's Finds in Mathematical Physics (Week 236)
  • · Replies 9 ·
Replies
9
Views
4K