Radio-frequency switches and related circuits
Radio-frequency switches and related circuits are disclosed. In some embodiments, a switching device can include a series arm having transistors implemented in a stack configuration between first and second nodes. The switching device can further include a shunt arm having transistors implemented in a stack configuration between the first node and a ground node. The switching device can further include a bias architecture having a series arm bias circuit and a shunt arm bias circuit. The series arm bias circuit can be configured to bias the transistors of the series arm and include a gate-gate resistor that couples each pair of neighboring transistors. The shunt arm bias circuit can be configured to bias the transistors of the shunt arm and include a gate-gate resistor that couples each pair of neighboring transistors.
1. A method for operating a radio-frequency switch, the method comprising:
providing a series arm including a plurality of transistors implemented in a stack configuration between a first node and a second node, each transistor having a source, a drain and a gate, the transistors configured to be in an ON state or an OFF state to respectively allow or inhibit passage of a signal between the first and second nodes;
providing a shunt arm including a plurality of transistors implemented in a stack configuration between the first node and a ground node, each transistor having a source, a drain and a gate, the transistors of the shunt arm configured to be in an ON state when the transistors of the series arm are in the OFF state, or an OFF state when the transistors of the series arm are in the ON state;
biasing the transistors of the series arm from a bias node through a feed node of the series arm and a circuit including a gate-gate resistor that couples each pair of neighboring transistors of the series arm, such that the gate of a selected transistor of the series arm is provided with a bias signal directly from the feed node of the series arm; and
biasing the transistors of the shunt arm from a bias node through a feed node of the shunt arm and a circuit including a gate-gate resistor that couples each pair of neighboring transistors of the shunt arm, such that the gate of an end transistor of the shunt arm is provided with a bias signal directly from the feed node of the shunt arm.
2. The method of claim 1 wherein the selected transistor of the series arm is a center transistor if the series arm has an odd number of transistors, or a first transistor from the center of the stack if the series arm has an even number of transistors.
3. The method of claim 1 wherein the end transistor of the shunt arm is on the side of the ground node.
4. The method of claim 1 wherein the first node is an input node and the second node is an output node for the signal.
5. The method of claim 1 wherein the second node is an input node and the first node is an output node for the signal.
6. A method for fabricating a radio-frequency switch, the method comprising:
forming or providing a series arm including a plurality of transistors implemented in a stack configuration between a first node and a second node, each transistor having a source, a drain and a gate, the transistors configured to be in an ON state or an OFF state to respectively allow or inhibit passage of a signal between the first and second nodes;
forming or providing a shunt arm including a plurality of transistors implemented in a stack configuration between the first node and a ground node, each transistor having a source, a drain and a gate, the transistors of the shunt arm configured to be in an ON state when the transistors of the series arm are in the OFF state, or an OFF state when the transistors of the series arm are in the ON state;
forming a series arm bias circuit configured to bias the transistors of the series arm from a bias node through a feed node of the series arm and a circuit including a gate-gate resistor that couples each pair of neighboring transistors of the series arm, such that the gate of a selected transistor of the series arm is provided with a bias signal directly from the feed node of the series arm; and
forming a shunt arm bias circuit configured to bias the transistors of the shunt arm from a bias node through a feed node of the shunt arm and a circuit including a gate-gate resistor that couples each pair of neighboring transistors of the shunt arm, such that the gate of an end transistor of the shunt arm is provided with a bias signal directly from the feed node of the shunt arm.
7. The method of claim 6 wherein the transistors of the series arm and the transistors of the shunt arm are implemented on a silicon-on-insulator substrate.
8. The method of claim 7 wherein the series arm bias circuit and the shunt arm bias circuit are implemented on the silicon-on-insulator substrate.
9. The method of claim 6 wherein the selected transistor of the series arm is a center transistor if the series arm has an odd number of transistors, or a first transistor from the center of the stack if the series arm has an even number of transistors.
10. The method of claim 6 wherein the end transistor of the shunt arm is on the side of the ground node.
11. The method of claim 6 further comprising forming a drain-source resistor that couples the drain and source of each transistor of the series arm.
12. The method of claim 6 further comprising forming a drain-source resistor that couples the drain and source of each transistor of the shunt arm.
13. The method of claim 6 further comprising forming a body-body resistor that couples bodies of each pair of neighboring transistors of the series arm.
14. The method of claim 6 further comprising forming a body-body resistor that couples bodies of each pair of neighboring transistors of the shunt arm.