Bias networks for dc or extended low frequency capable fast stacked switches

Abstract

Passive gate bias network topologies are implemented for stacked FET switch structures, which improve the settling time and low cut-off frequency for both DC and non-DC operation. DC capable stacked switch bias structures provide gate and bulk bias voltages, using input DC voltages, which are coupled to the gate terminals and the bulk terminals of the stacked switches. The DC coupling can be achieved using resistors, or a combination of resistors and diodes. An exemplary SPST switch includes a series stacked switch in combination with a shunt stacked switch, which can be controlled between alternating states. For low cut-off frequency improvement structures, an input signal is coupled to the gate terminals and bulk terminals of the switches in the stacked switches, using a DC block capacitor and resistors. The low cut-off of the bulk can be improved by connecting the bulk terminal of one switch to the opposite polarity switch.