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Active FET mixer with multiple RF input channels, how to avoid DC blocks?

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Georgy.Moshkin

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fet-mixer.png
I am trying to avoid use of DC-blocks (top schematic).
Bottom schematic gives poor results, deteriorated mixing quality and mixing results are not as I expect. As I understand, mixing products IF1 and IF2 are leaking to each other (bottom schematic), and this schematic must be somehow corrected analogous to quadrature diode mixer, where common microstrip circuit is tied to ground through high impedance biasing line which is part of DC return path.

In my final schematic I want to use 4 RF input channels and have four mixing products: IF1 IF2 IF3 IF4. Adding DC blocks requires separate Vd connection for each transistor, and somewhat complicates RF layout and reduces conversion gain.
 

Perhaps you could move the drive levels instead of
blocking / restoring the RF signals away / to ground.
Keep the RF path ground referred and move the chop
high/low levels.
 
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