THE EFFECT OF BODY CONTACT SERIES RESISTANCE ON SOI CMOS AMPLIFIER STAGES

This paper examines some implications for analogue design of using bod y ties as a solution to the problem of floating body effects in partia lly-depleted (PD) SOI technologies. Measurements on II-gate body-tied structures in a 0.7-mu m SOI process indicate body-tie series resistan ces increasing into the M Omega region, Both circuit simulation and me asurement results reveal a delayed but sharper kink effect as this res istance increases. The consequences of this effect are shown in the co ntext of a simple amplifier configuration, resulting in severe bias-de pendent degradation in the small signal gain characteristics as the bo dy-tie resistance enters the M Omega region. It is deduced that imperf ectly body tied devices may be worse for analogue design than using no body tie at all.