Hello all .. i want to ask about biasing Passive mixer just 4 MOS as switches .. but i want to set the Dc Output Common mode .. for them ... any idea how can i do this without large flicker noise due to dc bias

thanks

I suppose you could use a resistor divider from a power supply to set the common mode to some fraction of the supply. This voltage will obviously track supply changes and also potentially let noise on the supply couple to the mixers, but it is simple. The gate bias would need to be supply referenced too such that the overdrive on the switches doesn't vary with supply.