By Adam Taylor

I just received the most interesting email from Antti at Trenz, in which he pointed out that he had designed a 500MHz radio receiver using just four resistors, four capacitors, and a Xilinx series 7 FPGA. How did he do this? He is keeping that to himself for the moment. However, Antti thinks it would a great idea to open a challenge based upon this design to see if others in the FPGA community can explain how he achieved this. Of course, for the winners who supply the correct answer there will be Trenz goodies as prizes. (See below.)

The diagram below shows the components allowed to solve this challenge. You can redraw them if necessary to clarify the schematic. The values of R and C do not need to be optimized.

To prove that this is possible, the screen shots below show the input and the recovered signal inside the FPGA.

By this point I was thinking Delta Sigma ADC using the FPGA’s LVDS inputs. (There are papers and articles about this technique online.) However, Antti tells me this is not his solution and he was kind enough to provide a few hints for this challenge below:

All you need to know is really in the diagram. You can print it out, take a pencil and complete the challenge. If you are not familiar with Xilinx FPGA’s you may have to read some Xilinx datasheets. You may have to read the Challenge description many times. The minimal digital circuitry used inside of the Xilinx FPGA to demonstrate the operation of this radio receiver can be made within less than two hours with Xilinx Vivado. If you are very fast, maybe in less than one.

Because they have so many Trenz prizes to give away to the winners, Antti has created three categories:

UltraFast - This is very simple. The first person who sends an email to Antti with a working solution, or with a solution that we cannot prove to be non-working, is the winner. There is no need to calculate the values for the resistors or capacitors or to make any performance estimates. Your sole goal is to be the first to solve the Challenge correctly.

Maker DIY hacker - To win in this category, you need to provide a working solution; you must implement it; and you must provide a photo of your setup and some measurement results. Bonus points are given if you use your design for some cool application.

Ultimate Theory - To win in this category, you need to provide a working solution. You will however get higher ranking if you:





Provide some reasonable values for the resistors and capacitors or actually calculate them and provide the calculations. You provide additional solutions with fewer components (and less performance). You provide an enhanced solution adding minimal numbers of resistors and capacitors (no other components).

The closing date for entries is July 3rd. The judges will be Antti and myself (Adam Taylor).

If you want to enter your solution in any category email challenge@trenz.biz