Why do some systems use a frequency doubler instead of a PLL? Do DDS spurs change with phase shift of, for example, 90 degrees versus 0?
On behalf of Jeff Keip.
A simple frequency doubling design can be much simpler to design than a full PLL, and require less circuitry. If you are shifting phase repeatedly, you will introduce some spurious, but it is likely to be pretty close to the noise floor I would expect. I