This paper presents small-signal design consideration for two-dimensional change-over switch GaN monolithic microwave integrated circuits (MMICs). For the design of two-dimensional change-over single pole single throw (SPST) switch circuit which electrically changes between low pass filter and high pass filter, the demands for design conditions are as follows: 1. two-dimensional switch with time/frequency domain. 2. The sufficient isolation in off-state at the signal frequencies for both low band and high band. Two-dimensional change-over single pole double throw (SPDT) switch provides a duplexer for frequency division duplex operation and an SPDT switch for time division duplex operation for low-cost the fifth generation (5G) front-ends (FEs). GaN two-dimensional change-over SPST and SPDT MMIC switches are successfully demonstrated by using 0.25 μm GaN foundry process for high power handling capability in 5G FEs. The demonstrated GaN MMIC switches shows almost the same two-dimensional switching characteristics as the designed ones.