Guided by the switch-signal theory

the operations of current transmission switch used to describe the action of threshold-controllable switch in multiple-valued Schmitt trigger were established

and novel current-mode CMOS ternary and quaternary Schmitt triggers with output current and voltage signal were presented.The hysteresis current values of multiple-valued Schmitt triggers were controlled by only sizing the transistor aspect ratios.The main properties of the circuit are its simple structure

fully adjustable hysteresis and suitable for low-voltage applications.The designed circuits are simulated using HSPICE program and the model parameters of a TSMC 0.25 μ m CMOS process

with 1.5V power supply.From the simulation results

the effectiveness of the proposed approach and the ideal characteristic of multiple-valued Schmitt circuit are validated.