Improvements on the Design of the Low Saturation Onset Transistor

The LSOT (low saturation onset transistor) is a four-transistor network that emulates a MOS device with much lower saturation onset voltage by compensating the reverse saturation component of the drain current through its main transistor. Due to current overcompensation in the structure, the DC output characteristic of the equivalent device may present an undesirable hump. This work presents a methodology to properly size the LSOT leading to a smoother characteristic. Moreover, the addition of a simple switch to automatically cut-off an auxiliary branch of the LSOT structure is also proposed, to allow the use of shorter devices without augmenting overall power.