T. Tanaka et al., High frequency characteristics of dynamic threshold-voltage MOSFET (DTMOS)under ultra-low supply voltage, IEICE TR EL, E82C(3), 1999, pp. 538-543
Dynamic Threshold-Voltage MOSFETs (DTMOS) in which the body is connected to
the gate provide extremely high transconductance for supply voltages as lo
w as under 0.7 V. This is because the forward body-source bias lowers the t
hreshold voltage, which results in large gate drive and large drain current
. This paper describes the high frequency characteristics of DTMOS for the
first time. The DTMOS we analyzed has a small parasitic resistance due to e
mploying optimized Co salicide technology. It also has a small parasitic ca
pacitance due to a reduction in the overlapping region between the gate and
drain, which is achieved by employing gate poly-Si oxidation prior to LDD
implantation. We obtained an F-t of 78 GHz and an F-max of 37 GHz for a 0.1
-mu m-L-eff DTMOS even at a supply voltage of 0.7 V. We also observed an F-
max enhancement by 1.5 times for a 0.12-mu m-L-eff DTMOS compared to a conv
entional SOI MOSFET, which we attributed to high transconductance and large
output resistance. The DTMOS can be considered as the most promising devic
e for low-power RF LSIs.