Frequency Mixer

Dear Expert

May I know why in the design of the synthesizer or other circuit for the RF Communication there was frequency mixer in there?
Why we need to mix the input frequency with the other frequency? What is the purpose ?

Please advice.

Thank you very much.

Peter

If you add two frequencies together, you get four frequencies:
100 + 10 gives you:
100
10
110
90

If you add two frequencies that are close together, you get:
210+200=
210
200
410
10

If you put your signal through a mixer you can pick which frequency to work with after the mixer.

If everyone who designs radios designs their radios to mix signals and come out with signals on 10, electronic circuit makers can design circuits for processing signals on 10. You buy premade modules and plug them together. Cheap easy, convenient.

Mixers bring radio signals that could be on a wide variety of frequencies to a single standard frequency. It would not be 10, with 20 mHz wide channels. But that's why they do it.

Hi

Is it meaning that the mixer is act as frequency selection?
As I know the output from the mixer only have 2 frequency which is f1-f2 and f1+f2. Correct?
Then how about the freq counter (N)?
Please the attahement for detailed.

Please advice

Thanks.
Peter

Attached Images

 

The device in that image is a

PLL - Phase Locked Loop. Whole different thing entirely. No mixer.

No. 4 outputs:
f1
f2
f1+f2
f1-f2



Superheterodyne Receivers

This is a topic you study in electronic school in your second year, after you have studied basic electronics for a year. It can not be explained in 25 words or less.

Perhaps he is thinking of "Double Balanced Mixers".