Switch circuit and semiconductor device
View Patent ↗A switch circuit for passing or blocking a high-frequency signal includes a correction circuit for correcting an impedance component that exists in the switch circuit and that changes asymmetrically with the direct-current potential as a reference such that impedance as seen from either high-frequency terminal changes symmetrically with the direct-current potential as a reference in response to positive and negative changes that take the direct-current potential of the high-frequency signal as a reference.
1. A switch circuit for passing or blocking a high-frequency signal, comprising a correction circuit for correcting impedance that is present between ground and any terminal in the switch circuit and that changes asymmetrically with the direct-current potential of said high-frequency signal as reference, such that impedance seen from either of high-frequency terminals changes symmetrically with said direct-current potential as reference in response to positive and negative change that takes said direct-current potential as reference.
2. The switch circuit according to claim 1 , wherein:
impedance that changes asymmetrically with said direct-current potential as a reference is impedance of ground parasitic capacitance; and
said correction circuit includes a correction capacitance element for balancing the impedance of said ground parasitic capacitance.
3. The switch circuit according to claim 2 , further comprising:
a switch unit provided with: a first high-frequency terminal and a second high-frequency terminal that receive and supply said high-frequency signals, and a plurality of field-effect transistors connected in a series between said first high-frequency terminal and said second high-frequency terminal;
wherein said ground parasitic capacitance is parasitic capacitance between the ground potential and the gate electrodes of said field-effect transistors.
4. The switch circuit according to claim 3 , wherein said correction circuit is connected between said first high-frequency terminal and the gate electrode of at least one field-effect transistor that is connected in a series.
5. The switch circuit according to claim 3 , wherein said correction circuit is connected between the gate electrode of at least one field-effect transistor that is connected in a series and the drain of that field-effect transistor.
6. The switch circuit according to claim 1 , further comprising a switch unit provided with: a first high-frequency terminal and a second high-frequency terminal that receive and supply said high-frequency signal, a plurality of field-effect transistors connected in a series between said first high-frequency terminal and said second high-frequency terminal, and resistance elements connected between a control terminal and the gate electrodes of said field-effect transistors; wherein:
the impedance that changes asymmetrically with said direct-current potential as a reference is the impedance of resistance elements connected between said control terminal and the gate electrodes of said field-effect transistors; and
said correction circuit includes correction resistance elements for balancing impedance with the impedance of said resistance elements.
7. The switch circuit according to claim 6 , wherein said correction circuit is capacitance elements and resistance elements for correction connected in a series.
8. The switch circuit according to claim 6 , wherein the value of resistance elements connected between said control terminal and the gate electrodes of said field-effect transistors is equal to the value of said correction resistance elements.
9. The switch circuit according to claim 6 , wherein said correction circuit is connected between the gate electrode of at least one field-effect transistor that is connected in a series and said first high-frequency terminal.
10. The switch circuit according to claim 6 , wherein said correction circuit is connected between the gate electrode of at least one field-effect transistor that is connected in a series and the drain of that field-effect transistor.
11. The switch circuit according to claim 1 , further comprising a switch unit provided with: a first high-frequency terminal and a second high-frequency terminal that receive and supply said high-frequency signal, a plurality of field-effect transistors connected in a series between said first high-frequency terminal and said second high-frequency terminal, and resistance elements connected between a control terminal and the gate electrodes of said field-effect transistors; wherein:
the impedance that changes asymmetrically with said direct-current potential as a reference is the impedance of the ground parasitic capacitance between the ground potential and the gate electrodes of said field effect transistors and the impedance of the resistance elements connected between said control terminal and the gate electrodes of said field-effect transistors;
said correction circuit includes:
correction capacitance elements for balancing impedance with the impedance of said ground parasitic capacitance between the ground potential and the gate electrodes of said field-effect transistors; and
correction resistance elements for balancing impedance with the impedance of the resistance elements connected between said control terminal and the gate electrodes of said field-effect transistors; and
said correction circuit is connected between said first high-frequency terminal and the gate electrode of at least one field-effect transistor that is connected in a series.
12. The switch circuit according to claim 1 , further comprising a switch unit provided with: a first high-frequency terminal and a second high-frequency terminal that receive and supply said high-frequency signal, a plurality of field-effect transistors connected in a series between said first high-frequency terminal and said second high-frequency terminal, and resistance elements connected between a control terminal and the gate electrodes of said field-effect transistors; wherein:
the impedance that changes asymmetrically with said direct-current potential as a reference is the impedance of the ground parasitic capacitance between the ground potential and the gate electrodes of said field effect transistors and the impedance of the resistance elements connected between said control terminal and the gate electrodes of said field-effect transistors;
said correction circuit includes:
correction capacitance elements for balancing impedance with the impedance of said ground parasitic capacitance between the ground potential and the gate electrodes of said field-effect transistors; and
correction resistance elements for balancing impedance with the impedance of the resistance elements connected between said control terminal and the gate electrodes of said field-effect transistors; and
said correction circuit is connected between the gate electrode of at least one field-effect transistor that is connected in a series and the drain of that field-effect transistor.
13. The switch circuit according to claim 4 , including a plurality of switch units that share said first high-frequency terminal.
14. The switch circuit according to claim 3 , wherein said capacitance elements are parasitic capacitance between said drain or source and an extension realized by an extension of the gate electrode arranged parallel to the end portion of the drain or the end portion of the source of a field-effect transistor.
15. The switch circuit according to claim 3 , wherein said capacitance elements are parasitic capacitance between said drain or source and an interconnect that is arranged parallel to the end portion of the drain or the end portion of the source and that is connected to the gate electrode of a field-effect transistor.
16. The switch circuit according to claim 3 , wherein said capacitance elements are parasitic capacitance between the resistance elements that are connected to the gate electrode of a field-effect transistor and the source that is formed with an insulating film interposed between the source and said resistance elements.
17. A semiconductor device provided with the switch circuit according to claim 1 .
18. The switch circuit according to claim 5 , including a plurality of switch units that share said first high-frequency terminal.
19. The switch circuit according to claim 9 , including a plurality of switch units that share said first high-frequency terminal.
20. The switch circuit according to claim 10 , including a plurality of switch units that share said first high-frequency terminal.
21. The switch circuit according to claim 11 , including a plurality of switch units that share said first high-frequency terminal.
22. The switch circuit according to claim 12 , including a plurality of switch units that share said first high-frequency terminal.
23. The switch circuit according to claim 11 , wherein said capacitance elements are parasitic capacitance between said drain or source and an extension realized by an extension of the gate electrode arranged parallel to the end portion of the drain or the end portion of the source of a field-effect transistor.
24. The switch circuit according to claim 12 , wherein said capacitance elements are parasitic capacitance between said drain or source and an extension realized by an extension of the gate electrode arranged parallel to the end portion of the drain or the end portion of the source of a field-effect transistor.
25. The switch circuit according to claim 11 , wherein said capacitance elements are parasitic capacitance between said drain or source and an interconnect that is arranged parallel to the end portion of the drain or the end portion of the source and that is connected to the gate electrode of a field-effect transistor.
26. The switch circuit according to claim 12 , wherein said capacitance elements are parasitic capacitance between said drain or source and an interconnect that is arranged parallel to the end portion of the drain or the end portion of the source and that is connected to the gate electrode of a field-effect transistor.
27. The switch circuit according to claim 11 , wherein said capacitance elements are parasitic capacitance between the resistance elements that are connected to the gate electrode of a field-effect transistor and the source that is formed with an insulating film interposed between the source and said resistance elements.
28. The switch circuit according to claim 12 , wherein said capacitance elements are parasitic capacitance between the resistance elements that are connected to the gate electrode of a field-effect transistor and the source that is formed with an insulating film interposed between the source and said resistance elements.