RF Signal Generator Project - Part 1

I've decided that this summer I'm going to attempt to build an RF Signal Generator. I'm not yet sure if I'll have time to complete it, but there are a few reasons why I'm taking it on.

Firstly, I want a challenging project that will push me to actually implement a device that makes use of all the skills I've been learning over the past few years. Especially this year, I've been paying lots of attention to RF/Microwave devices, and test equipment.

Secondly, after going over the architecture of modern RF SigGens, it looks like it will be possible to make the system bit by bit, and still have a working instrument in the meantime. I can develop new sections to improve usability, and performance, and add them in when they're done. Some examples of this might be, improving the user interface, adding an output attenuator,  adding upconversion stages and filtering for higher bandwidth, adding/improving the reference oscillator, or VCOs for better phase noise performance, etc.

Thirdly, a signal generator is useful for testing RF/Microwave devices. It'll be good to have one on the bench. I haven't seen a heap of home jobs that extend into the GHz range, so perhaps this is ambitious, but I'm thinking that with the the number of off-the-shelf parts available now, some of the hard work has already been done.

Lastly, I'm hoping that while doing this I'll learn a lot about what goes into building those fancy instruments from the likes of Keysight, Rohde & Schwarz, Tek, and the like. It'd be great to work for one of those companies one day, and I think this is a good step towards that.





To start (and after a few days of reading), I've ordered a cheap RF Synthesizer board to get a rough idea of what I've got to build on. This one is based on the ADF4351 from Analog Devices (pictured left).
http://www.ebay.com.au/itm/202074367762

The other unit pictured is based off the same chip, but obviously with a different enclosure & UI.

I'd like to produce something better, and design my own circuits & PCBs for this, but this could be a good benchmark. Many of the relevant ICs from Texas Instruments, Linear Tech, or Analog Devices, are available with evaluation modules, and I'm sure they'll be useful for evaluating parts before putting them into the design.

In terms of form factor & overall system design, that is a fair way off :).

Finally, a list of things I want to learn more about over the life of this project.
  • PLLs
  • VCOs
  • Phase Noise
  • Up/Down Conversion
  • Modulation
  • Step Attenuators
  • Analog Signal Multiplexing
  • EM Simulation
  • RF System Integration
  • C++ (for the UI)
  • RTOS and/or an Embedded OS

Comments

Popular Posts