Hi

I want to ask some thing very simple



wat are the demerits /merits of a synthesizer aginst a VCO



uzmeed

Hi,
Synthesizer is a closed loop system where as the VCO an open loop, quite obvious answer.
Looking at the implementation part of the VCO, you would require a bank of voltage sources, if you wanted to change the frequency output. Synthesizer vaoids this problem by being a closed loop aystem. If fixed frequency is your requirement then one can make a VCO and keep the voltage constant.
There are certain architectures which compensates for the temperature, power supply variation effect on an oscillator, but this requires a synthesizer.
Noise output of the oscillator is of main concern, whatever may be the application. Possibility of having reduced noise can be achieved by using differential arcitectures of the VCO and having self biasing techniques for the same, so as to achieve more power supply noise rejection.
hope this helps.
Regards,
V