RF isolation switch circuit
First Claim
1. An apparatus comprising:
- a main N-channel transistor having a first terminal, a second terminal, and a gate terminal and configured for passing a Radio Frequency (RF) signal;
a first turn-off N-channel transistor having a first terminal, a second terminal, and a gate terminal, wherein the second terminal of the first turn-off N-channel transistor is coupled to the gate terminal of the main N-channel transistor;
a second turn-off N-channel transistor having a first terminal, a second terminal, and a gate terminal, wherein the second terminal of the second turn-off N-channel transistor is coupled to the first terminal of the first turn-off N-channel transistor, and wherein the first terminal of the second turn-off N-channel transistor is coupled to the first terminal of the main N-channel transistor; and
a first control conductor, wherein the main transistor is turned off when a first digital control signal on the first control conductor has a first digital logic value, and wherein the main transistor is turned on when the first digital control signal on the first control conductor has a second digital logic value opposite the first digital logic value.
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Accused Products
Abstract
In a first aspect, an RF switch includes a main transistor and a gate-to-source shorting circuit. When the RF switch is turned off, the gate-to-source shorting circuit is turned on to short the source and gate of the main transistor together, thereby preventing a Vgs from developing that would cause the main transistor to leak. When the RF switch is turned on, the gate-to-source shorting circuit is turned off to decouple the source from the gate. The gate is supplied with a digital logic high voltage to turn on the main transistor. In a second aspect, an RF switch includes a main transistor that has a bulk terminal. When the RF switch is turned off, the bulk is connected to ground through a high resistance. When the RF switch is turned on, the source and bulk are shorted together thereby reducing the threshold voltage of the main transistor.
45 Citations
37 Claims
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1. An apparatus comprising:
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a main N-channel transistor having a first terminal, a second terminal, and a gate terminal and configured for passing a Radio Frequency (RF) signal; a first turn-off N-channel transistor having a first terminal, a second terminal, and a gate terminal, wherein the second terminal of the first turn-off N-channel transistor is coupled to the gate terminal of the main N-channel transistor; a second turn-off N-channel transistor having a first terminal, a second terminal, and a gate terminal, wherein the second terminal of the second turn-off N-channel transistor is coupled to the first terminal of the first turn-off N-channel transistor, and wherein the first terminal of the second turn-off N-channel transistor is coupled to the first terminal of the main N-channel transistor; and a first control conductor, wherein the main transistor is turned off when a first digital control signal on the first control conductor has a first digital logic value, and wherein the main transistor is turned on when the first digital control signal on the first control conductor has a second digital logic value opposite the first digital logic value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method comprising:
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controlling a main transistor of an RF isolation switch circuit to turn off by coupling a gate of the main transistor to a source of the main transistor through a gate-to-source shorting circuit, and by supplying a digital logic low voltage onto the gate of the main transistor, wherein the gate-to-source shorting circuit includes a first turn-off transistor having a second terminal coupled to the gate of the main transistor and having a first terminal coupled to an intermediate node, and wherein the gate-to-source shorting circuit further includes a second turn-off transistor having a second terminal coupled to the intermediate node and a first terminal coupled to the source of the main transistor, wherein the main transistor and the gate-to-source shorting circuit are parts of the RF isolation switch circuit wherein the main transistor is configured for passing an RF signal; and controlling the main transistor to turn on by turning off the first and second turn-off transistors of the gate-to-source shorting circuit and by supplying a digital logic high voltage onto the gate of the main transistor. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An apparatus comprising:
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a main N-channel transistor having a source terminal, a drain terminal, a bulk terminal, and a gate terminal; a first switch transistor having a first terminal coupled to the bulk terminal of the main N-channel transistor, a second terminal coupled to the source terminal of the main transistor, and a gate terminal; a second switch transistor having a first terminal coupled to the bulk terminal of the main N-channel transistor, a second terminal, and a gate terminal; a ground conductor; and a resistor having a first lead coupled to the second terminal of the second switch transistor and having a second lead coupled to the ground conductor, the resistor switchably coupled by the second switch transistor to the bulk node the first lead further coupled to the second terminal of the second switch transistor. - View Dependent Claims (18, 19, 20, 21)
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22. A method comprising:
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(a) controlling a main transistor of an RF isolation switch circuit to turn off by supplying a digital logic low voltage onto a gate terminal of the main transistor, by decoupling a bulk terminal of the main transistor from a source terminal of the main transistor, and by coupling the bulk terminal of the main transistor to a ground conductor through a resistor; and (b) controlling the main transistor to turn on by supplying a digital logic high voltage onto the gate terminal, by coupling the bulk terminal to the source terminal, and by decoupling the bulk terminal from the ground conductor. - View Dependent Claims (23, 24, 25)
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26. An apparatus comprising:
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a main N-channel transistor having a source terminal, a drain terminal, a bulk terminal, and a gate terminal; a first turn-off N-channel transistor having a first terminal, a second terminal, and a gate terminal, wherein the second terminal of the first turn-off N-channel transistor is coupled to the gate terminal of the main N-channel transistor; a second turn-off N-channel transistor having a first terminal, a second terminal, and a gate terminal, wherein the second terminal of the second turn-off N-channel transistor is coupled to the first terminal of the first turn-off N-channel transistor, and wherein the first terminal of the second turn-off N-channel transistor is coupled to the source terminal of the main N-channel transistor; a first switch transistor having a first terminal coupled to the bulk terminal of the main N-channel transistor, a second terminal coupled to the source terminal of the main transistor, and a gate terminal; a second switch transistor having a first terminal coupled to the bulk terminal of the main N-channel transistor, a second terminal, and a gate terminal; a ground conductor; a resistor having a first lead coupled to the second terminal of the second switch transistor and having a second lead coupled to the ground conductor; and a first control conductor, wherein the main transistor is turned off when a first digital control signal on the first control conductor has a first digital logic value, and wherein the main transistor is turned on when the first digital control signal on the first control conductor has a second digital logic value opposite the first digital logic value. - View Dependent Claims (27, 28, 29)
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30. A method comprising:
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(a) controlling a main transistor of an RF isolation switch circuit to turn off by supplying a digital logic low voltage onto a gate terminal of the main transistor, by decoupling a bulk terminal of the main transistor from a source terminal of the main transistor, by coupling the gate terminal of the main transistor to the source terminal of the main transistor, and by coupling the bulk terminal of the main transistor to a ground conductor through a resistor; and (b) controlling the main transistor to turn on by supplying a digital logic high voltage onto the gate terminal, by coupling the bulk terminal to the source terminal, by decoupling the gate of the main transistor from the source of the main transistor, and by decoupling the bulk terminal from the ground conductor. - View Dependent Claims (31)
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32. An apparatus comprising:
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an input signal conductor; means for switching having a first electrode, a second electrode, and a control electrode, wherein an RF input signal having a frequency of at least 500 MHz is present on the first electrode; and means for shorting the first electrode to the control electrode when a control signal on the input signal conductor has a first digital logic level and for controlling the means for switching such that the means for switching is off when the control signal has the first digital logic level, wherein the means for shorting is also for decoupling the first electrode from the control electrode when the control signal has a second digital logic level opposite the first digital logic level and for controlling the means for switching to be on off when the control signal has the second digital logic level. - View Dependent Claims (33, 34)
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35. A method of manufacture comprising the steps of:
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fabricating a main N-channel transistor having a first terminal, a second terminal, and a gate terminal and configured for passing an RF signal; fabricating a first turn-off N-channel transistor having a first terminal, a second terminal, and a gate terminal, wherein the second terminal of the first turn-off N-channel transistor is coupled to the gate terminal of the main N-channel transistor; fabricating a second turn-off N-channel transistor having a first terminal, a second terminal, and a gate terminal, wherein the second terminal of the second turn-off N-channel transistor is coupled to the first terminal of the first turn-off N-channel transistor, and wherein the first terminal of the second turn-off N-channel transistor is coupled to the first terminal of the main N-channel transistor; and fabricating a control conductor that is coupled to the main transistor such that the main transistor is turned off when a digital control signal on the control conductor has a first digital logic value and such that the main transistor is turned on when the first digital control signal on the first control conductor has a second digital logic value opposite the first digital logic value, wherein the main N-channel transistor, the first turn-off N-channel transistor, the second turn-off N-channel transistor, and the first control conductor are parts of an RF switch. - View Dependent Claims (36, 37)
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Specification