High-speed FPGA to CPU Interface

From time to time one has the need to transfer lots of data between an FPGA and a CPU. Unfortunately, there are not that many ways to do that, if you want to get more than a couple MByte/s.

GPS Disciplined Oscillator

From time to time I get asked, what to use as accurate time source (better than a few microseconds) or frequency reference (better than one ppm). One affordable way to get there is to use a GPS disciplined oscillator (GPSDO). This post elaborates on some of the choices you have when shopping for a GPSDO and the issues you can expect.

FPGA based Time to Digital Converters

There are many ways to measure time of an event precisely. Probably the most common way is to use a counter, as for example used in the timer units of micro-controllers. Unfortunately, this approach is limited in precision to the clock at which the counter runs. A micro-controller gets usually to 10-20ns, while high performance systems might get down to 1ns. If higher precision is needed, then a method that runs independent of the system clock is required.

Harmonics of Ring Oscillators

Ring oscillators are probably the most prevalent oscillators these days. They are the oscillator of choice for most micro-controllers and are used more and more often in RF systems as well, due to their low space requirements and easy integration. Having such a wide use, you would think, they are pretty well described in literature, but quite the contrary is true.

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