A common gate input circuit for III/V D-mode Buffered FET Logic (BFL) maximizes the dynamic range to drive a level shift section to set the proper voltage levels to switch the BFL and allows for decoupling of the switch point from the dynamic range. A common gate switching section includes a D-mode FET (FET1) configured as a load and a D-mode FET (FET2) configured as a common gate connected in series between high and low supplies Vdd and Vee1 (typically ground potential). The gate electrode of FET2 is coupled to Vee1 and the source electrode of FET2 is driven by the external digital signals. This eliminates the additional supply Vss, thus maximizing the dynamic range of the section to switch between Vdd and Vee1 and decouples the dynamic range from the switch point. An input level shift section may shift the Data In to the source electrode of FET2 to shift the switch point and to present a high input impedance.