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Interview questions about LNA and Mixer ??

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yolande_yj

yolande_yj

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I am having an interview this weekend. I am reviewing what I did before. Can you give me some questions about LNA and Mixer design? They could be from very basic to advanced. And also any basic question about RF design is welcome. Please give me a hand, thanks.
 

Mixer:
types?
advantages of each type?
gilbertcell mixer?
increasing linearity?
increasing gain?
noise figure?
noise cancellation?
sources of noise?
low voltage applications?
 

    yolande_yj

    yolande_yj

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before LNA the noise
simple noise qustions ,
noise of the filter , equivalent noise band width
MOS transistors noise sources , the corner frequency of the flicker noise

LNA
====
noise matching , impedance matching
increasing gain
which to use CG , CS ?
degeneration

many many more

khouly
 

    yolande_yj

    yolande_yj

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Lets say you had a receiver front end, that consisted of a 30 dB LNA with a 2 dB noise figure, that fed a mixer with a 6 dB conversion loss. The desired operating frequency is 10 GHz, the LO frequency is 9 GHz, so the IF frequency is at 1 GHz.

You go out into the lab and make a noise figure measurement. You expect the system noise figure to be a little higher than 2 dB, but instead you are surprised to see the noise figure meter reading 5.3 dB. What is up? What do you have to do to get the system down to a 2.2 dB noise figure?
 

    yolande_yj

    yolande_yj

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    K

    kanchana 29

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biff44 said:
Lets say you had a receiver front end, that consisted of a 30 dB LNA with a 2 dB noise figure, that fed a mixer with a 6 dB conversion loss. The desired operating frequency is 10 GHz, the LO frequency is 9 GHz, so the IF frequency is at 1 GHz.

You go out into the lab and make a noise figure measurement. You expect the system noise figure to be a little higher than 2 dB, but instead you are surprised to see the noise figure meter reading 5.3 dB. What is up? What do you have to do to get the system down to a 2.2 dB noise figure?
Click to expand...

I guess you are asking about the SSB NF right? Adding a SAW filter (image rejection) before the mixer can lower down the NF by 3dB. Using mixer + polyphase filter also can reject the image.
Thanks.
 

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