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frequency divider IC for PLL loop recommendations

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Etesla:
Hi all,

I'm trying to make a PLL controlled FM transmitter using readily available parts. I'm a fan of using some version of the CD4046 PLL as the central building block, with an external common collector colpitts oscillator with varistors as the VCO. For this to work at 100 Mhz, however, I need to capture the frequency of the output of the VCO and divide it down (the 4046 variants only work up to around 36 MHZ). I see that some circuits online (https://www.electronicsforu.com/electronics-projects/high-fidelity-fm-transmitter) use digital circuitry to divide down the 100 MHZ to something lower, but I'm skeptical that using the sinusoidal output of the VCO to trigger digital logic would work reliably. Overall, I need some integrated circuit that can divide down the frequency of the output of the VCO, preferably one that's designed for that purpose. With that in mind, here are my two questions:

1.) Is it common or advisable to just use digital logic to divide down an analog signal like in the linked schematic?
2.) Are there IC's that are intended to do this dividing down an analog frequency into a lower digital frequency that are in stock with distributors today?

Thank you!

Benta:
Search for prescalers. ON Semiconductor is a good place to look.

Theboel:
Hi,

I never use 4046 as VCO but MC12019 is a good candidate for Your prescalers

Etesla:
The MC120XX prescalers were something I looked into. They seem to be the only 'prescaler' IC's on digikey. However, their minimum output frequency was 100 MHz, and I'd prefer to be using the chip I choose well within its limits. The most attractive IC for this purpose I have found was the UPB571, but I can't find it in stock anywhere. If anyone knows an IC like the UPB571 with similar characteristics in terms of sensitivity, frequency range, and division factors that's in stock, that's really what I'm looking for. I think they're called "dual-modulus prescalers" in general, but there's no subcategory for that on the websites of distributors...

Benta:
Sorry for my bad advice. It seems that both ON and NXP have killed off the MC120xx prescalers. I wasn't aware of that.

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