1-N(2) MOS CASCODE CIRCUITS AND THEIR APPLICATIONS

This paper describes an N-type and a P-type MOS cascode circuit based on the square-law characteristics of an MOS transistor in saturation r egion. The transconductance parameter ratios of an upper and a lower M OS transistor are set to be 1:n(2) for the N-type MOS cascode circuit and n(2):1 for the P-type MOS cascode circuit. The N and P-type MOS ca scode circuits are divided to four types by the difference of connecti ons of input terminals. We consider the input-output relations of each type circuit. The second-order effects of the circuit such as channel length modulation effect, mobility reduction effect and device mismat ch are analyzed. As applications, an analog voltage adder and a V-T le vel shifter using MOS cascode circuits are presented. All of the propo sed circuits are Very simple and consist of only the N and P-type MOS cascode circuits. The proposed circuits are confirmed by SPICE simulat ion with MOSIS 1.2 mu m CMOS process parameters.