master_picengineer
Banned
pll reverso
Hi all,
Please help me finding a respose to this question.
In practicle the output frequency of a VCO is a function of the value of the controlling voltage input Vc. If we assume that the VCO power Supply is 3 V and taht it should be between 1V and 2 V. Suppose that the output frequency of the VCO is supposed to be maintained at f_o. This means that I have to maintain the voltage Vc (which is the output of the charge pump circuit) stable. ( let say at 1.5 V ).
We know that, if Vc increase f decrease and Vice versa.
My question is
When we have f=f_o then we must have Vc=1.5 which is not the case since the output of the Charge pump in such situation is zero.
In other word, how to design circuit that:
- decreases Vc when f<f_o
- increase Vc when f>f_o
- Maintain Vc=1.5V if f=f_o ?
I know solution that use the Amp op in order to perform the comparaison task but I'm looking for the most simple circuit responding to my question.
Hi all,
Please help me finding a respose to this question.
In practicle the output frequency of a VCO is a function of the value of the controlling voltage input Vc. If we assume that the VCO power Supply is 3 V and taht it should be between 1V and 2 V. Suppose that the output frequency of the VCO is supposed to be maintained at f_o. This means that I have to maintain the voltage Vc (which is the output of the charge pump circuit) stable. ( let say at 1.5 V ).
We know that, if Vc increase f decrease and Vice versa.
My question is
When we have f=f_o then we must have Vc=1.5 which is not the case since the output of the Charge pump in such situation is zero.
In other word, how to design circuit that:
- decreases Vc when f<f_o
- increase Vc when f>f_o
- Maintain Vc=1.5V if f=f_o ?
I know solution that use the Amp op in order to perform the comparaison task but I'm looking for the most simple circuit responding to my question.