Tiny DDS – Open source DDS generator


The homemade function generator is a quite common project on the internet. We can find different ways to do it:

– The quick & dirty way based on a DDS module bought on eBay
– The analog version based on a MAX038 / XR2206
– The “clean” way based on a FPGA and a fast DAC (e.g. http://www.circuitben.net/node/14)
– The software way (e.g. Arduino + R/2R DAC)

From my side, I wanted a small one which could fits my needs without being too expensive. According to me, such generator should at least:

Tiny DDS – Open source DDS generator

– Be easy to use
– Output a signal from 1Vpp to 10Vpp (+/-5V), from 0 to 1MHz
– Have a low profile
– Without electric hazard (shall work on a 12V DC)

Choosing the DDS chip

I first started to look for a cheap DDS chip on eBay; you have to be careful because most of DDS chips have only a sinusoidal output. Since I also want a triangular output, I have chosen the AD9834. According to its datasheet, this component is able to output a frequency of 37.5MHz from a clock of 75MHz… But do not expect a clean waveform at such frequency: without an internal PLL, this signal would be defined by only 2 points.

From my personal experience, I consider that a waveform shall be defined by 10-20 points to be well restituted. Relying on a 75MHz clock, the maximal output frequency would be 7.5MHz… This is not a very good performance for a professional equipment (even if the cheapest generators do not go above 4MHz), but it is quite reasonable for a hobbyist project.

The AD9834 can be found at $5 on eBay.


For more detail: Tiny DDS – Open source DDS generator

About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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