Bypass circuitry to improve switching speed
AssigneepSemi Corporation
InventorsRavindranath D. Shrivastava, Simon Willard, Peter Bacon
Life of this patent
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Abstract
Methods and devices to improve the switching speed of radio frequency FET switch stacks are disclosed. The described methods and devices are based on bypassing drain-sources resistors when the FET switch stack is transitioning from an ON to an OFF state. Several implementations of the disclosed teachings are also presented.
Claims19
A radio frequency (RF) field effect transistor (FET) switch stack comprising:
- FET transistors arranged in a stacked configuration;
- one or more first drain-source resistors, each first drain-source resistor coupled across drain-source terminals of a corresponding FET transistor of the FET transistors;
- one or more drain-source bypass switches, each drain-source bypass switch coupled across corresponding one or more first drain-source resistors;
- and
- a switching control block configured to control the drain-source bypass switches, the switching control block comprising one or more FET control switches configured to be in a control switch OFF state when the FET transistors are in a stack OFF state or a stack ON state and to be in a control switch ON state when the FET transistors are transitioning from the stack ON state to the stack OFF state.
A method for switching a radio frequency (RF) FET switch stack comprising FET transistors and drain-source bypass switches coupled across corresponding drains-sources of the FET transistors, and a switching control block configured to control the drain-source bypass switches, the switching control block comprising one or more FET control switches, the RF FET switch stack being configured to be in a stack ON state and in a stack OFF state, the drain-source bypass switches being configured to be in a drain-source bypass switch ON state and in a drain-source bypass switch OFF state, the method comprising:
- controlling the drain-source bypass switches;
- switching the FET control switches into a control switch OFF state when the FET transistors are in a stack OFF state or a stack ON state, and
- switch the FET control switches into a control switch ON state when the FET transistors are transitioning from the stack ON state to the stack OFF state.
A radio frequency (RF) field effect transistor (FET) switch stack comprising:
- FET transistors arranged in a stacked configuration;
- one or more first drain-source resistors, each first drain-source resistor coupled across drain-source terminals of a corresponding FET transistor of the FET transistors;
- one or more drain-source bypass switches, each drain-source bypass switch coupled across corresponding one or more first drain-source resistors;
- a switching control block configured to control the drain-source bypass switches, the switching control block comprising
- one or more FET control switches in a stacked configuration, and
- one or more second drain-source resistors coupled across corresponding one or more FET control switches;
- the one or more FET control switches being configured to be in a control switch OFF state when the FET transistors are in the stack OFF state or the stack ON state and to be in a control switch ON state when the FET transistors are transitioning from the stack ON state to the stack OFF state, thereby bypassing the one or more second drain-source resistors;
- and
- the switching control block being configured to:
- generate a first control signal to turn the drain-source bypass switches from the drain-source bypass switch OFF state to the drain-source bypass switch ON state when the FET transistors are transitioning from the stack ON state to the stack OFF state, and
- couple the first control signal to the drain-source bypass switches through the one or more FET control switches.
Dependencies are inferred from the claim text.