Theory of current transmission switches and its application to design of a novel current-mode CMOS ternary Schmitt trigger

Guided by the switch-signal theory, this paper introduces design theory suitable for current-mode CMOS circuits at switch level. On this basis, the operations of current transmission switch used to describe the action of threshold-controllable switch in Schmitt trigger are established, and a novel current-mode CMOS ternary Schmitt trigger with ternary output current or/and voltage signal is presented. The two hysteresis current values of ternary Schmitt trigger are controlled by only sizing the transistor aspect ratio. The main properties of the circuit are its simple structure, fully adjustable hysteresis and suitable for low-voltage applications. A design example and the HSPICE simulation results with a power supply of 1.5V are given.