HIGH FREQUENCY SOLID STATE SWITCHING FOR IMPEDANCE MATCHING
First Claim
1. A circuit of a variable reactance element of an impedance matching network comprising:
- a reactance element coupled between a first voltage line and a first node;
a first diode having an anode coupled to the first node and a cathode coupled to a second node;
a second diode having an anode to couple to a second voltage line and a cathode to couple to the first node;
a transistor having a first, second, and control terminals, wherein;
the first terminal is coupled to the second node;
the second terminal is coupled to the second voltage line;
the control terminal is coupled to a controller; and
the reactance element is switched into the variable reactance element when the transistor is on and switched out after the transistor is off.
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Accused Products
Abstract
In accordance with this invention the above and other problems are solved by a switching apparatus and method that uses a switching circuit having a pair of parallel solid-state diodes (e.g., PN or PIN diodes), one of which is connected to a transistor (e.g., power MOSFET or IGBT), to switch a capacitor (or reactance element) in or out of a variable capacitance element (or variable reactance element) of an impedance matching network. Charging a body capacitance of the transistor reverse biases one of the two diodes so as to isolate the transistor from the RF signal enabling a low-cost high capacitance transistor to be used. Multiple such switching circuits and capacitors (or reactance elements) are connected in parallel to provide variable impedance for the purpose of impedance matching.
51 Citations
28 Claims
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1. A circuit of a variable reactance element of an impedance matching network comprising:
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a reactance element coupled between a first voltage line and a first node; a first diode having an anode coupled to the first node and a cathode coupled to a second node; a second diode having an anode to couple to a second voltage line and a cathode to couple to the first node; a transistor having a first, second, and control terminals, wherein; the first terminal is coupled to the second node; the second terminal is coupled to the second voltage line; the control terminal is coupled to a controller; and the reactance element is switched into the variable reactance element when the transistor is on and switched out after the transistor is off. - 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. A switching circuit for a reactance element of an impedance matching network comprising:
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a first node coupling the switching circuit to the reactance element; a second node; a first diode having an anode coupled to the first node and a cathode coupled to the second node; and a transistor coupled to the second node and turned off in order to switch the reactance element out of the impedance matching network by a charging of a body capacitance of the transistor leading to a reverse bias voltage across the first diode. - View Dependent Claims (21, 22, 23, 24)
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25. A method of switching a reactance element out of a variable reactance element of an impedance matching network, the method comprising:
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turning a switch of the variable reactance element off; charging a body capacitance of the switch so as to reverse bias a diode having a cathode coupled to a terminal of the switch and an anode coupled to a terminal of the reactance element; and reducing an RF current through the reactance element as a result of the reverse bias of the diode so as to switch the reactance element out of the variable reactance element. - View Dependent Claims (26, 27, 28)
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Specification