Re: PLL Question
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Brian being GM8BJF
Yes, use an OPAMP gain stage. I use the LM6211 which is a 20MHz bandwidth chip that can operate up to 24V, and have used it with LMX2470 and LMX2487 synth chips to drive VCOs that take a tuning voltage greater than 5V.
Rather than a buffer / gain stage though, the complete loop filter is built around the LM6211 which end up as an inverting stage so the appropriate config bit in the synth chip to ser negative phase detector polarity needs to be set. http://g4jnt.com/LMX2470_DevModule.pdf gives more details.