The effect of body contact series resistance on SOI CMOS amplifier stages

This paper examines some implications for analogue design of using body ties as a solution to the problem of floating body effects in partially-depleted (PD) SOI technologies. Measurements on H-gate body-tied structures in a 0.7-μm SOI process indicate body-tie series resistances increasing into the MΩ region. Both circuit simulation and measurement results reveal a delayed but sharper kink effect as this resistance increases. The consequences of this effect are shown in the context of a simple amplifier configuration, resulting in severe bias-dependent degradation in the small signal gain characteristics as the body-tie resistance enters the MΩ region. It is deduced that imperfectly body tied devices may be worse for analogue design than using no body-tie at all