While the GI is in ‘‘integration’’ or ‘‘hold’’ state, the reset switch
has to be kept off. However the effect of leakage current in the GI
reset switch will cause errors to the output in the long duration of
these states. To eliminate this effect, the single reset switch was replaced
by a T-switch configuration shown in Fig. 6.
The leakage current of DMOS switch is composed of the source/
body reverse leakage current and the drain/source subthreshold
current. Since the source/body reverse leakage current can be negligible
in SD5400, the drain to source subthreshold current becomes
the main factor of the ‘‘off’’ current. If the source and
body are at the same potential, the drain/source of a MOS transistor
in the deep subthreshold region of operation is given by