An SOI floating body charge monitor technique

SOI pass transistor circuits are vulnerable to initial-cycle parasitic bipolar current which can cause speed degradation or functional failures (Kuang et al, 1997; Lu et al, 1997). This paper describes a novel floating body charge monitoring method which effectively reduces the sensitivity of transient response in the initial cycles and improves circuit robustness and noise margin without using body-contacted devices. In doing so, we avoid the area penalty, issues of contact resistance, and modeling difficulties associated with body contacts. The charge monitor mimics the circuit configuration and biasing characteristics of a particular circuit, such as the MUX topology, which is prone to bipolar current-induced initial-cycle slowdown. When excess body charge is detected by the monitor circuit, an additional discharge path is automatically enabled to provide more switching current and thus minimize timing variation.