Amplitude-phase canceling circuit for switch linearity
Amplitude-phase canceling circuit for switch linearity. In some embodiments, a radio-frequency switch circuit can include first and second switch arms, with each switch arm including a plurality of transistors arranged in series to form a stack between a first node and a second node. The first node of the first switch arm can be coupled to the first node of the second switch arm. The radio-frequency switch circuit can further include an amplitude-phase cancelling block implemented across one or more transistors of each switch arm, and configured such that a third harmonic resulting from an ON state of the first switch arm is substantially canceled by a third harmonic resulting from an OFF state of the second switch arm.
1. A radio-frequency switch circuit comprising:
first and second switch arms, each switch arm configured as a respective signal path and including a plurality of transistors arranged in series to form a stack between a first arm node and a second arm node, the first arm node of the first switch arm coupled to the first arm node of the second switch arm; and
an amplitude-phase cancelling block implemented to be parallel to a plurality of transistors of each switch arm, and configured such that a third harmonic resulting from an ON state of the first switch arm is substantially canceled by a third harmonic resulting from an OFF state of the second switch arm, the amplitude-phase cancelling block including a first block arranged in series with a second block, each block including first and second nodes such that the second node of the first block is coupled to the first node of the second block, each block including a series arrangement of the respective first node, a first resistance, a middle node, a second resistance and the respective second node, a first transistor having source and drain coupled to each other and to the middle node and a gate coupled to the first node, and a second transistor having source and drain coupled to each other and to the middle node and a gate coupled to the second node, body of the first transistor connected directly to body of the second transistor.
2. The radio-frequency switch circuit of claim 1 wherein the first and second blocks are configured to generate harmonics by a voltage distributed by a voltage divider formed by the resistances of the first and second blocks.
3. The radio-frequency switch circuit of claim 2 wherein a capacitance between the gate and the coupled source/drain of the first transistor and a capacitance between the gate and the coupled source/drain of the second transistor are selected to provide respective phase shifts of the harmonics.
4. The radio-frequency switch circuit of claim 3 wherein the first and second blocks of the amplitude-phase cancelling block are configured to generate substantially nil amount of a second harmonic.
5. The radio-frequency switch circuit of claim 1 wherein the amplitude-phase cancelling block is implemented with the respective switch arm in a symmetric manner.
6. The radio-frequency switch circuit of claim 5 wherein the number of transistors between the amplitude-phase cancelling block and the first arm node is the same as the number of transistors between the amplitude-phase cancelling block and the second arm node.
7. The radio-frequency switch circuit of claim 5 wherein each switch arm is configured to be operated with the first arm node as an input node, or with the second arm node as an input node.
8. The radio-frequency switch circuit of claim 1 wherein the amplitude-phase cancelling block is implemented with the respective switch arm in an asymmetric manner.
9. The radio-frequency switch circuit of claim 8 wherein each switch arm is configured to be operated with one of the first and second arm nodes as an input node, and the other arm node as an output node.
10. The radio-frequency switch circuit of claim 1 wherein at least the plurality of transistors are implemented as field-effect transistors.
11. The radio-frequency switch circuit of claim 10 wherein the field-effect transistors are implemented as silicon-on-insulator devices.
12. A semiconductor die comprising:
a substrate; and
a radio-frequency switch circuit implemented on the substrate, and including first and second switch arms, each switch arm configured as a respective signal path and including a plurality of transistors arranged in series to form a stack between a first arm node and a second arm node, the first arm node of the first switch arm coupled to the first arm node of the second switch arm, the radio-frequency switch circuit further including an amplitude-phase cancelling block implemented to be parallel to a plurality of transistors of each switch arm, and configured such that a third harmonic resulting from an ON state of the first switch arm is substantially canceled by a third harmonic resulting from an OFF state of the second switch arm, the amplitude-phase cancelling block including a first block arranged in series with a second block, each block including first and second nodes such that the second node of the first block is coupled to the first node of the second block, each block including a series arrangement of the respective first node, a first resistance, a middle node, a second resistance and the respective second node, a first transistor having source and drain coupled to each other and to the middle node and a gate coupled to the first node, and a second transistor having source and drain coupled to each other and to the middle node and a gate coupled to the second node, body of the first transistor connected directly to body of the second transistor.
13. The semiconductor die of claim 12 wherein the substrate includes a silicon-on-insulator substrate.
14. A radio-frequency module comprising:
a packaging substrate configured to support a plurality of components; and
a radio-frequency switch circuit implemented on the packaging substrate, and including first and second switch arms, each switch arm configured as a respective signal path and including a plurality of transistors arranged in series to form a stack between a first arm node and a second arm node, the first arm node of the first switch arm coupled to the first arm node of the second switch arm, the radio-frequency switch circuit further including an amplitude-phase cancelling block implemented to be parallel to a plurality of transistors of each switch arm, and configured such that a third harmonic resulting from an ON state of the first switch arm is substantially canceled by a third harmonic resulting from an OFF state of the second switch arm, the amplitude-phase cancelling block including a first block arranged in series with a second block, each block including first and second nodes such that the second node of the first block is coupled to the first node of the second block, each block including a series arrangement of the respective first node, a first resistance, a middle node, a second resistance and the respective second node, a first transistor having source and drain coupled to each other and to the middle node and a gate coupled to the first node, and a second transistor having source and drain coupled to each other and to the middle node and a gate coupled to the second node, body of the first transistor connected directly to body of the second transistor.