STM32 ANALOG CONVERTER phase noise

[Avian] has been utilizing STM32 ARM processors to sample RF for a range of applications. At first, he was getting fairly broad TV signals. Recently, though, he’s started handling extremely narrow signals as well as he discovered that his samples had a great deal of spread in the frequency domain that he didn’t expect.

What complied with was some detective work that resulted in a decision that phase noise was the culprit. however why? [Avian] took some measurements as well as discovered that the phase noise practically precisely matched the phase noise specification for the STM32’s phase locked loop (PLL).

Unfortunately, there didn’t seem to be a great method to prevent utilizing the PLL without major modifications to the rest of the circuit. However, it was rather the discovering experience as well as something to be conscious of when counting on built-in converters for high-accuracy measurements.

One of the very best things about this publish is the references to much more information. There’s a fantastic explanation of phase noise, in addition to a particular application note about clock jitter as well as analog converters.

We’ve talked about phase noise in direct digital synthesis a few times. however usually, it is quite apparent like when you are asking a CPU to double as an RF transmitter. [Avian’s] publish was a bit much more of a detective story.