HELP ME TO DESIGN AN ACTIVE MIXER??

[half1st]

mixer design hand calculation

helo everyone..i have a really big problem..i dunno how to design an active mixer..what is the 1st step should i take before design the mixer?what kind of MESFET is suitable for the mixer?how to calculate the parameters of the mixer??i really dunno what should i do..plz someone help me!!!!!the mixer should be operate for 38GHz with bandwidth 100MHz..plz help me design an active microstrip mixer???!!!!!:|:|:|:|:|:|:|

 

[khouly]

mmm , do u want it discrete on board mixer, or an integrated mixer using one of the GaAs processes

khouly

 

[half1st]

tq for replying..
what is different between discrete on board mixer and an integrated mixer using one of the GaAs processes? does the mixer design involve any calculation?

 

[khouly]

sure mixer design will invlove hand calculations. but the design of board level mixer will be different from IC mixer

Khouly

 

[half1st]

ooo...i see..i use PCB RO4003C..board level..

 

[Abhishekabs]

Are you sure 38 GHz mixer on Rogers 4003C substrate?
Do you have any previous experience of mixer design for lower band of frequencies?
such as C band or X band?

 

[half1st]

i dont have any experience on designing mixer..however one of my fren had design a diode mixer for 27GHz with the same substrate.have any prob with RO4003C?do you have any suggestion?

 

[Abhishekabs]

Well for 38 GHz your lambada will be 7.8 mm.
so choose substrate with high Er so that atleast your lambada(λg) will increase
So your micro strip design will be comparatively easy to design & fabricate.

Can you tell me how your friend has designed mixer for 27GHz?
Means which components he has used etc.etc.

 

[half1st]

actually, she was design a rat race mixer using schottky diode for her master thesis..i don't know what else components she was used..tq for your opinion. where do you get the 7.8mm value?what else calculations that i should know?i am a student in Malaysia and this is my first time get involve with mixer..

 

[Abhishekabs]

Ok. Since she has designed using mixer diodes. I guess the substrate she has used is ok.
But if you are using transistors, I can not advice you. khouly will tell you how to design using transistor.

Also You need to study microstrip theory first.
Since this is basic equation C= F * λ
λ= 3 * 10^8/ 38 * 10^9
0.0078 meter.

Then you need to calculate λg, E eff etc.
Start reading microwave mixer by mass & any micro strip book or tutorials first.
It is not easy to design 38 GHz mixer.

 

[half1st]

tq for your advise..do you familiar with microwave mixer?

 

[Abhishekabs]

Well I have knowledge of how to design mixer using diodes.
only up to 6GHz. But not up to 38GHz

 

[half1st]

dear khouly,

do you know what IF input power that can accepted by AMMC-3041 mixer by Avago?

 

[Abhishekabs]

check the datasheet of AMMC-3041

 

[khouly]

half1st dou wnat upconversion mixer or down conversion mixer
the max IF for this device is 5 dBm for up conversion and 16 dBm for down conversion

khouly