VCO center frequency

[Pavithra18]

I know VCO centre frequency is the mid-freq between the lowest and hightest frequencies of the signal bandwidth but what is the use of this frequency... I mean what can we understand abt the system from this centre frequency?

 

[davenn]

its not necessarily any particular use
often a VCO can be used over its full range when used ... say as a sweep generator.
Saying the VCO has a centre freq of specific use is meaningless

that is ... say if the VCO had a range from 1000 to 3000MHz. the centre freq of 2000MHz is just another freq point
within its range

Dave

 

[lw1ecp]

Normally, best circuit performance (lowest locking delay, lowest distortion, etc.) is attained if you choose VCO center frequency in the middle of the incoming signal bandwidth. E. g. if the VCO is part of a locked FM demodulator, after an IF strip of 10.7MHz, it makes sense to choose a center frequency of 10.7MHz for this block.
I am trying to figure an exception, it could be having to deal with a signal with an asymetrical spectrum, such as demodulating analog TV with an I/Q detector, your VCO must be locked to the picture carrier, which is NOT in the middle of the channel. Of course, you can choose a VCO whose central f is far away from this carrier, but you risk locking onto a wrong signal (e. g. the sound carrier or an interfering station).