LO harmonics effect on FET mixer

[karote]

Hi all,

Could some one give me an answer about how does the even order harmonics of strong LO signal affect on FET mixer? Does the second order harmonics cause performance degradation? Of course they will produce mixing results but does they affect on the output signal quality on the fundamental frequency (RF_OUT)

Thank you in advance

 

[A.Anand Srinivasan]

only the odd harmonics are generally worried about because the even harmonics contribute mainly to the DC and dont contribute to the signal from the fundamental frequency....

 

[fanshuo]

why even harmonic contribute mainly to the DC?

 

[A.Anand Srinivasan]

well nonlinearity of the transfer function can be represented using equation in cosine/sine.... if u manipulate by using a cosine/sine input you will understand......

 

[khouly]

in single FET the LO 2nd harmonic will have an effect , and sure if ur filter is not good sure the output singal will be affected

i agree with A Anand if the mixer is differetial , here the even harmonics will be minimum but in singel FET mixer this not ture

khouly

 

[A.Anand Srinivasan]

in single FET the LO 2nd harmonic will have an effect , and sure if ur filter is not good sure the output singal will be affected

i agree with A Anand if the mixer is differetial , here the even harmonics will be minimum but in singel FET mixer this not ture

khouly

i was thinking that the even harmonic will contribute only to the DC... actually it was a inference from the manipulation of some equations for a non-linear system...

can u just clarify what all components will the 2nd harmonic introduce and will there be a component in the fundamental frequency....

 

[khouly]

i was design a mixer based on single fet , the 2nd harmonic of the LO , mixer with the RF , and there was a signal like IF but shifted to the 2L0-RF

khouly