current-mode passive mixer problem

I am designing a current-mode passive mixer which consists of gm,mixer core and tia stages. The mixer core is ac coupled to the first stage. I wonder about the input offset voltage of tia, is it feedback by the resistor or other ways?
I tried to use the feedback resister. The input and output common mode voltage is vcc/2 at most times. (using spectre dc analysis) But as I tried to enlarge the ratio of input and load mosfets to mitigate flicker noise. The cm voltage becames vcc. The input mosfets are pmos.
Since there is no dc voltage or current after mixer core. If the input node of tia begins with a random voltage like vcc. Then it seems that the whole circuit can`t work. Why not just bias the input node (vcc/2) of tia with a large resistante?
Thank you for your help