passive Mixer Vs Active Mixer

[Muhammed_1]

Hello all please i want to know

1. which one of them have more flicker noise ?

2. How can we remove the image noise to make SSB NF equals to DSB NF ?

3. what is the difference between V-V mixer and V-I-V mixer ?

thanks in advance

 

[vfone]

Flicker noise is related to crystal surface defects in semiconductors, and can be found in any semiconductor device.
But because flicker noise is proportional with bias current, this makes somehow the active devices to have higher flicker noise power.

Mixer DSB NF includes signal and noise inputs from both sidebands.
Mixer SSB NF assumes signal input from only one sideband, but noise inputs from both sidebands. Using an image filter to eliminate the image response (to do accurate NF measurement) does not help because it changes the image-frequency embedding impedance, changing the noise temperature.
This is the reason that in the device specifications is mentioned what type of NF was measured, SSB or DSB.

 

[Muhammed_1]

thanks vfone... but i mean is there any method to reject this noise form the image frequency , I think that will make SSB NF equals to DSB NF ..right ??

 

[vfone]

Yes, the only difference between SSB and DSB is the NF

 

[Muhammed_1]

so what about difference between passive voltage mixer and passive Current mixer .....

i think the difference between voltage and current is in NF in voltage is higher than Current Mixing.

but which one is high Linearity IIP3 ?