Resonant tunneling diodes (RTDs) have functional versatility and high speed switching capability. The integration of resonant tunneling diodes and MOS transistor makes threshold gates and logics. The design and fabrication of linear threshold gates will be presented based on a monostable bistable transition logic element. Each of its input terminals consist out of a resonant tunnelling diode merged with a transistor device. The circuit models of RTD and MOSFET are simulated in HSPICE. Two input XOR gate is designed and tested.