[sdiy] DC-1 MHz, through-zero FM, controlled, oscillator without core capacitor

[brianw]

On Dec 2, 2025, at 5:32 PM, Donald Tillman wrote:
> On Dec 1, 2025, at 8:21 AM, cheater cheater wrote:
>> 
>> A PLL would mean completely digital control, wouldn't it?
> 
> PLLs are analog.  I'm not sure what you mean by "digital control".

PLLs can be implemented as either analog or digital.

In fact, some Texas Instruments TMS320 DSP chips have both DPLL (digital) and APLL (analog). Their PLL implementations are described such that the analog PLL is more noise tolerant and has less long-term jitter, and thus they recommend it when interfacing to USB.

I certainly don't know what the difference is between digital and analog PLL, but the differences are useful enough to implement both on the same chip (and I happen to find it interesting that an "analog" PLL can be implemented on a Digital Signal Processor die).

Brian Willoughby