Fractional-n PLL

Mike H Meyer

Other Parts Discussed in Thread: CDCE913

Does TI have a fractional-n pll with an internal VCO that can run at 75 MHz? I've looked and I can find a couple of integer-n but not fractional-n.

over 14 years ago

0 Firoj Kabir over 14 years ago

TI__Expert 4585 points

CDCE913 ( and other devices in this family) has fractional-N PLL, but VCO runs at 80 MHz minimum. The device has output divider. So, you can run the VCO at higher frequency (as for example 150 MHz) and generate 75 MHz.

Thanks,

Firoj

0 Mike H Meyer over 14 years ago in reply to Firoj Kabir

Expert 1560 points

Sounds great. Thanks for your help.

0 Mike H Meyer over 14 years ago in reply to Mike H Meyer

Expert 1560 points

Firoj, any idea how a modulation scheme at the input could work with the part? The application uses the clock to communicate modulated data and the concern is that the internal loop filter may compensate this out. Any thoughts?

0 Firoj Kabir over 14 years ago in reply to Mike H Meyer

TI__Expert 4585 points

The concern is valid. The PLL has a few hundred kHz loop bandwidth - depending on PLL settings. So, there is possibility that modulated data can be filtered out.

Thanks,

Firoj

Clock & timing

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Fractional-n PLL