Multiplying with 11 using PIC

[eltra11]

Do not understand exactly what do you mean by sentence : "The PIC could switch in 1 of 2 or 3 PLL's for workable operating ranges."
My idea is that PIC should detect the frequency frame in which PPL will be locked.For instance the first frame will be 1 Hz to 20 Hz, the second from 20 Hz to 200 Hz, third from 200 Hz to 2000 Hz, etc.Means PIC will detect the input frequency coming to PIC input pin (and also to PLL) which have to be multiplied by 11, and accordingly will switch the right low pass filter into VCO input.The input frequency will change in value every 5 minutes.
So idea is to switch elements in low pass filter in PLL, not to switch the whole PLL's.

[Ioannis]

The VCO of the PLL has a limited range that can work with specific R and C values. That is why you may need 3 discrete PLL's and have the PIC to decide which one will work at any time.

Ioannis

[amgen]

switching the r or c values might work good..... the switch or transistor might have to work 'bidirectionally' I think though.

[Ioannis]

The capacitor switching is difficult as it is directly connected to the pins of 4046. The resistor R1 in the datasheet, is connected to gnd. So, maybe two or three mosfets like a 2N7000 can select one of each to define the frequency range.

Also, a SN74LV4046A will be needed to be able to cover the 11MHz range. A CD4046 at 5V will not be able to work over 800KHz.

Ioannis