Switch circuit and method of switching radio frequency signals
DCFirst Claim
1. An RF switch circuit for switching RF signals, comprising:
- (a) a first input port receiving a first RF input signal;
(b) a second input port receiving a second RF input signal;
(c) an RF common port;
(d) a first switch transistor grouping comprising a plurality of FETs having channels series coupled in a stacked configuration, one end of the series-connected channels being a first node coupled to the first input port, the opposite end of the series-connected channels being a second node coupled to the RF common port, the first switch transistor grouping having a control node that is driven by a switch control signal (SW) and is coupled to a gate of each of the plurality of FETs of the grouping via a corresponding gate impedance;
(e) a second switch transistor grouping comprising a plurality of FETs having channels series coupled in a stacked configuration, one end of the series-connected channels being a first node coupled to the second input port, the opposite end of the series-connected channels being a second node coupled to the RF common port, the first switch transistor grouping having a control node that is driven by an inverse (SW_) of the switch control signal (SW) and is coupled to a gate of each of the plurality of FETs of the grouping via a corresponding gate impedance;
(f) a first shunt transistor grouping comprising one or more FETs arranged in a stacked configuration, one end of the series-connected channels being a first node coupled to the second input port, the opposite end of the series-connected channels being a second node coupled to ground, the first shunt transistor grouping having a control node that is driven by a switch control signal (SW) and is coupled to a gate of each of the one or more FETs of the grouping via a corresponding gate impedance; and
(g) a second shunt transistor grouping comprising one or more FETs arranged in a stacked configuration, one end of the series-connected channels being a first node coupled to the first input port, the opposite end of the series-connected channels being a second node coupled to ground, the first shunt transistor grouping having a control node that is driven by an inverse (SW_) of the switch control signal (SW) and is coupled to a gate of each of the one or more FETs of the grouping via a corresponding gate impedance;
(h) wherein the control signals SW and SW_have approximately equal magnitude but opposite polarity with respect to ground;
wherein, when SW is enabled, the first switch and shunt transistor groupings are enabled while the second switch and shunt transistor groupings are disabled, thereby passing the first RF input signal through to the RF common port and shunting the second RF input signal to ground; and
wherein when SW is disabled, the second switch and shunt transistor groupings are enabled while the first switch and shunt transistor groupings are disabled, thereby passing the second RF input signal through to the RF common port and shunting the first RF input signal to ground.
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Abstract
An RF switch circuit and method for switching RF signals that may be fabricated using common integrated circuit materials such as silicon, particularly using insulating substrate technologies. The RF switch includes switching and shunting transistor groupings to alternatively couple RF input signals to a common RF node, each controlled by a switching control voltage (SW) or its inverse (SW_), which are approximately symmetrical about ground. The transistor groupings each comprise one or more insulating gate FET transistors connected together in a “stacked” series channel configuration, which increases the breakdown voltage across the series connected transistors and improves RF switch compression. A fully integrated RF switch is described including control logic and a negative voltage generator with the RF switch elements. In one embodiment, the fully integrated RF switch includes an oscillator, a charge pump, CMOS logic circuitry, level-shifting and voltage divider circuits, and an RF buffer circuit.
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Citations
27 Claims
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1. An RF switch circuit for switching RF signals, comprising:
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(a) a first input port receiving a first RF input signal; (b) a second input port receiving a second RF input signal; (c) an RF common port; (d) a first switch transistor grouping comprising a plurality of FETs having channels series coupled in a stacked configuration, one end of the series-connected channels being a first node coupled to the first input port, the opposite end of the series-connected channels being a second node coupled to the RF common port, the first switch transistor grouping having a control node that is driven by a switch control signal (SW) and is coupled to a gate of each of the plurality of FETs of the grouping via a corresponding gate impedance; (e) a second switch transistor grouping comprising a plurality of FETs having channels series coupled in a stacked configuration, one end of the series-connected channels being a first node coupled to the second input port, the opposite end of the series-connected channels being a second node coupled to the RF common port, the first switch transistor grouping having a control node that is driven by an inverse (SW_) of the switch control signal (SW) and is coupled to a gate of each of the plurality of FETs of the grouping via a corresponding gate impedance; (f) a first shunt transistor grouping comprising one or more FETs arranged in a stacked configuration, one end of the series-connected channels being a first node coupled to the second input port, the opposite end of the series-connected channels being a second node coupled to ground, the first shunt transistor grouping having a control node that is driven by a switch control signal (SW) and is coupled to a gate of each of the one or more FETs of the grouping via a corresponding gate impedance; and (g) a second shunt transistor grouping comprising one or more FETs arranged in a stacked configuration, one end of the series-connected channels being a first node coupled to the first input port, the opposite end of the series-connected channels being a second node coupled to ground, the first shunt transistor grouping having a control node that is driven by an inverse (SW_) of the switch control signal (SW) and is coupled to a gate of each of the one or more FETs of the grouping via a corresponding gate impedance; (h) wherein the control signals SW and SW_have approximately equal magnitude but opposite polarity with respect to ground; wherein, when SW is enabled, the first switch and shunt transistor groupings are enabled while the second switch and shunt transistor groupings are disabled, thereby passing the first RF input signal through to the RF common port and shunting the second RF input signal to ground; and
wherein when SW is disabled, the second switch and shunt transistor groupings are enabled while the first switch and shunt transistor groupings are disabled, thereby passing the second RF input signal through to the RF common port and shunting the first RF input signal to ground. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An RF switch circuit for switching RF signals, comprising:
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a) a first RF port capable of outputting or receiving a first RF signal; b) a second RF port capable of outputting or receiving a second RF signal; c) a switch transistor grouping having a first node coupled to the first RF port and a second node coupled to the second RF port, wherein the switch transistor grouping is controlled by a first switch control signal (SW); and d) a shunt transistor grouping having a first node coupled to the first RF port and a second node coupled to ground, wherein the shunt transistor grouping is controlled by a second switch control signal (SW_); and wherein when the first switch control signal SW is enabled, the switch transistor grouping is enabled and the shunt transistor grouping is disabled thereby electrically coupling the first RF port to the second RF port, and wherein when the second switch control signal SW_is enabled, the shunt transistor grouping is enabled while the switch transistor grouping is disabled thereby shunting the first RF port to ground. - View Dependent Claims (21, 22, 23)
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24. An RF switch circuit for switching RF signals, comprising:
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a) a first RF port capable of receiving or outputting a first RF signal (RF1); b) a second RF port capable receiving or outputting a second RF signal (RF2); c) an RF common port; d) a first switch transistor grouping having a first node coupled to the first RF port and a second node coupled to the RF common port, wherein the first switch transistor grouping is controlled by a first switch control signal; e) a second switch transistor grouping having a first node coupled to the second RF port and a second node coupled to the RF common port, wherein the second switch transistor grouping is controlled by a second switch control signal; f) a first shunt transistor grouping having a first node coupled to the second RF port and a second node coupled to ground, wherein the first shunt transistor grouping is controlled by the first switch control signal; and g) a second shunt transistor grouping having a first node coupled to the first RF port and a second node coupled to ground, wherein the second shunt transistor grouping is controlled by the second switch control signal; wherein, when the first switch control signal is enabled, the first switch and first shunt transistor groupings are enabled while the second switch and shunt transistor groupings are disabled, thereby electrically coupling the first RF port with the RF common port and shunting the second RF port to ground, and wherein when the first switch control signal is disabled and the second switch control signal is enabled, the second switch and shunt transistor groupings are enabled while the first switch and shunt transistor groupings are disabled, thereby electrically coupling the second RF port with the RF common port and shunting the first RF port to ground. - View Dependent Claims (25, 26, 27)
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Specification