A novel type of GaAs DCFL (direct-coupled FET logic) static flip-flop named MCFF (memory-cell-type flip-flop) is described. This circuit was implemented as a D-flip-flop and as a T-flip-flop IC (integrated circuit) using 0.5- mu m gate-length GaAs MESFETs fabricated by the advanced self-alignment process technique. An operating data bit rate of 10 Gb/s with a phase margin of 51 degrees was achieved in the D-flip-flop with a power dissipation of 98 mW. The maximum toggle frequency of 16 GHz was obtained in the T-flip-flop with a power dissipation of 48 mW.