Variable threshold voltage CMOS (VTCMOS) in series connected circuits

Characteristics of variable threshold voltage CMOS (VTCMOS) in series connected circuits are investigated by means of device simulation. It is found that the performance degradation due to the body effect in series connected circuits is suppressed by utilizing VTCMOS. Lowering the threshold voltage (V/sub th/) enhances the drive current and alleviates the degradation due to the series connected configuration. Therefore, larger body effect factor (/spl gamma/) results in lower V/sub th/ and higher on-current even in the series connected circuits. These characteristics are attributed to the velocity saturation phenomenon which reduces the drain saturation voltage (V/sub dsat/).