AC Coupling Modules for Bias Ladders

• Main Authors: Samal, Shashi Ketan, Willard, Simon Edward, Allison, Matt, Ranta, Tero Tapio
• Format: Patent
• Language: English
• Published: 22.02.2024
• Subjects: BASIC ELECTRIC ELEMENTS; BASIC ELECTRONIC CIRCUITRY; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; PULSE TECHNIQUE; SEMICONDUCTOR DEVICES

A positive-logic FET switch stack that does not require a negative bias voltage, exhibits high isolation and low insertion/mismatch loss, and may withstand high RF voltages. Embodiments include a FET stack comprising series-coupled positive-logic FETs (i.e., FETs not requiring a negative voltage supply to turn OFF), series-coupled on at least one end by an "end-cap" FET of a type that turns OFF when its VGS is zero volts. The one or more end-cap FETs provide a selectable capacitive DC blocking function or a resistive signal path. Embodiments include a stack of FETs of only the zero VGS type, or a mix of positive-logic and zero VGS type FETs with end-cap FETs of the zero VGS type. Some embodiments withstand high RF voltages by including combinations of series or parallel coupled resistor ladders for the FET gate resistors, drain-source resistors, body charge control resistors, and one or more AC coupling modules.