On-resistance and harmonic distortion in graded-channel SOI FD MOSFET

In this paper we analyze the advantages of asymmetric channel engineering on the MOS resistance behavior in quasi-linear operation, such as used in integrated continuous-time-tunable filters. The study of the two major figures of merit in such applications, i.e. on-resistance and non-linear harmonic distortion, is supported by measurements on conventional and graded-channel (GC) fully depleted (FD) SOI MOSFETs. The quasi linear I-V characteristics of GC transistors demonstrate a decrease of the on-resistance as the length of the low doped region into the channel is augmented and an improvement of the third order harmonic distortion (HD3), when compared with conventional transistors. A full comparison method between conventional and GC SOI MOSFETs is presented considering HD3 evolution with on-resistance tuning under low voltage of operation, demonstrating the significant advantages of the asymmetrical long channel transistors.