Can I apply FM to 74HCT4046 pin 12 (R2?)

Hi Brian,

Could you give me a little more info on what your end goal/ what you are wanting the device to do for you?

Dylan - I want to modulate the VCO (about 3MHz - 30MHz frequency range) with a non-sinusoidal baseband audio signal of about 5kHz bandwidth. Ordinarily, I would break the feedback loop between the loop filter and the VCO, then add the baseband FM to the (nearly DC) loop filter output in an opamp. I'm just wondering if I can use the "frequency offset" capability to simplify my life by modulating the current flowing through R2 instead.

Brian,

Okay I see what you are trying to do. I've never come across anyone using the device in this way, but theoretically if done correctly it could work. As you stated by controlling the current through R2, you will be able to dynamically adjust the offset. I recommend getting some samples and testing it to see if the device responds in the way you want it to.