Transistor finger spacing and dimension variation in electronic devices
A radio-frequency device comprises a first transistor including a first set of fingers having a first finger-to-finger spacing in a width dimension of the first transistor, and a second transistor in a series connection with the first transistor, the second transistor including a second set of fingers having a second finger-to-finger spacing in the width dimension that is greater than the first finger-to-finger spacing.
1. A radio-frequency device comprising:
a first transistor including a first set of fingers arranged in parallel, the first set of finger having a first finger-to-finger spacing;
a second transistor in a series connection with the first transistor, the second transistor including a second set of fingers arranged in parallel, the second set of fingers having a second finger-to-finger spacing that is greater than the first finger-to-finger spacing; and
a third transistor in adjacent series connection with the second transistor, the third transistor including a third set of fingers arranged in parallel, the third set of fingers having a third finger-to-finger spacing that is greater than the second finger-to finger spacing.
2. The radio-frequency device of claim 1 wherein the third transistor has a width that is greater than a width of the second transistor.
3. The radio-frequency device of claim 1 wherein the first and second transistors are silicon-on-insulator transistors.
4. The radio-frequency device of claim 1 wherein the first set of fingers are shorter than the second set of fingers.
5. The radio-frequency device of claim 1 wherein the first transistor occupies a smaller physical area than the second transistor.
6. The radio-frequency device of claim 1 wherein at least some of the first set of fingers have metal traces electrically coupled thereto to provide added capacitance.
7. The radio-frequency device of claim 1 wherein the first transistor covers a physical area equal to a physical area covered by the second transistor.
8. A wireless device comprising:
a transceiver configured to process radio-frequency signals;
a radio-frequency module in communication with the transceiver, the radio-frequency module including a first transistor including a first plurality of fingers having a first finger-to-finger spacing, a second transistor in a series connection with the first transistor, the second transistor including a second plurality of fingers having a second finger-to-finger spacing that is greater than the first finger-to-finger spacing, and a third transistor in a series connection with the first transistor and the second transistor, the third transistor including a third plurality of fingers having a third finger-to-finger spacing that id greater than the second finger-to-finger spacing; and
an antenna in communication with the radio-frequency module, the antenna configured to facilitate transmitting and/or receiving of the radio-frequency signals.
9. The wireless device of claim 8 wherein the radio-frequency module is a switch module.
10. The wireless device of claim 8 wherein the third transistor has a width that is greater than a width of the second transistor.
11. The wireless device of claim 8 further comprising a fourth transistor in a series connection with the third transistor, the fourth transistor including a fourth plurality of fingers having a fourth finger-to-finger spacing that is equal to third finger-to-finger spacing.
12. The wireless device of claim 8 wherein the second plurality of fingers are longer than the first plurality of fingers and shorter than the third plurality of fingers.
13. The wireless device of claim 8 wherein the first plurality of fingers consists of more fingers than the second plurality of fingers.
14. The wireless device of claim 8 wherein the first plurality of fingers are shorter than the second plurality of fingers.
15. The wireless device of claim 8 wherein the first transistor has a total periphery that is greater than a total periphery of the second transistor.
16. The wireless device of claim 8 wherein at least some of the first plurality of fingers have metal traces electrically coupled thereto to provide added capacitance.
17. The wireless device of claim 8 wherein the first transistor occupies a smaller physical area than the second transistor.
18. The wireless device of claim 8 wherein the first transistor has a physical area equal to a physical area of the second transistor.
19. A method of fabricating a switch comprising:
forming a first transistor on a semiconductor substrate, the first transistor having a first finger-to-finger spacing;
forming a second transistor on the semiconductor substrate in a series connection with the first transistor, the second transistor having a second finger-to-finger spacing that is greater than the first finger-to-finger spacing; and
forming a third transistor on the semiconductor substrate in a series connection with the second transistor, the third transistor having a third finger-to-finger spacing that is greater than the second finger-to-finger spacing.
20. The method of claim 19 wherein the third transistor has a width that is greater than the second transistor.
21. The method of claim 19 wherein the first transistor has a gate width that is shorter than a gate width of the second transistor.