phase shifting of the carrier

[dr.power]

The best way is to use a divide by 4 arrangement. It doesn't care about input duty cycle. This gives 90 degree LO shift over wide frequency range.

Do you know how to implement it by CMOS chips?

If you have an assured 50% input duty cycle you can create 90 degree shift with divide by 2 (one /2 is on pos edge, other /2 on neg edge). Any duty cycle variation will result in shift in 90 degree phasing.

I have got 4047 which produces 2 output signals which are 180 degrees out of phase, and of course are 50% duty cycle, But do not know how to implement the 90 & 270 degree on it?

And using squarewave is fine. Top chopping of a double Gilbert cell balanced mixer is fine with squarewave LO drive.

what that does mean really?

There are quite a few IC's that have divider and mixers in one chip. https://www.electro-tech-online.com/custompdfs/2011/08/2713DS-1.pdf

Do you know any else too?

Thanks

 

[Mikebits]

dr.power; you have made an inordinate amount of post seeking answers without even the slightest hint of you attempting to find the answers through research or work on your own. Personally I find your never ending post to things you could simply look up annoying.

If you want serious answers to your questions, then I would suggest you do you own research and homework, then come back with more intelligent questions. We are not free engineers for hire, but we are more than happy to help someone who has attempted to solve a problem on their own.

Nuf said???

 

[audioguru]

Pre-emphasis boosts high audio frequencies. But your circuit does not have pre-emphasis, instead it cuts high audio frequencies.

The series 8.2k resistor then a 3.9nF capacitor to ground cuts frequencies above 5kHz (like an AM radio) and the two 8.2k resistors with 10nf and 12nF capacitors is a 2nd-order Sallen and Key lowpass active filter that cuts frequencies above 1950Hz. The result is that high audio frequencies are removed and all important consonant sounds of speech are missing.

Your circuit will not work with an electret mic because the mic is not powered. It probably uses a dynamic mic (coil and magnet type).
All electret mics have a very flat frequency response from about 20Hz to about 15kHz or higher. Dynamic mics vary in their frequency response.

Ham radios have a very narrow frequency response with no high audio frequencies so pre-emphasis is not used.
Ham radios use severe distortion to "compress" voices, not a broadcast-quality compressor circuit that you have.
I dislike the sound of a compressor.