Balun design for differential narrowband LNA

[LakshmiJL]

Hi,

can anyone tell me how to design a balun for a differential narrow band LNA. Please help me with design equations if any.

Thank you

 

[BigBoss]

Us e this applet to calculate the components' values..
https://leleivre.com/rf_LCBalun.html

 

[LakshmiJL]

Working of LC Balun in differential LNA

Hi , can anyone please explain the working of a LC balun.how it is integrated with the differential LNA ,and its operation in detail

 

[LakshmiJL]

Working of LC Balun in differential LNA

Hi,
Can anyone please explain the working of LC balun in differential LNA. How does it function as a balun.
Please explain with regards to balun mentioned in the below link.



thank you

 

[BigBoss]

Re: Working of LC Balun in differential LNA

There 2 sections known as High Pass and Low Pass section.
At the resonance frequency, the Phase is +270 degree ( 180 degree coming from transformer is included ) on High Pass section.Similarly, the Phase is -90 degree on Low Pass section at the resonance frequency.
When you combine these phases into one, you obatin 0 degree so the signals are "in-phase"

 

[LakshmiJL]

Thank you . Can you also explain, how does it produce a phase shift at high pass and low pass section.

 

[BigBoss]

Thank you . Can you also explain, how does it produce a phase shift at high pass and low pass section.

Calculate their transfer function and plot Magnitude and Phase response..You will see them at the cut-off frequencies..

 

[BradtheRad]

Re: Working of LC Balun in differential LNA

View attachment 111527

Another way to see the behaviors...

Is by redrawing this as two LC tanks. One is a bandpass, the other a bandstop:



And separated, to illustrate individual functions: