Phase-Switched Impedance Modulation Amplifier

• US 20160181987A1
• Filed: 12/19/2015
• Published: 06/23/2016
• Est. Priority Date: 12/19/2014
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Perreault, David J., Jurkov, Alexander Sergeev
• Granted Patent: US 9,923,518 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 1/565 using inductive elements
• CPC Class Codes: H03F 2200/301 the loading circuit of an amplifying stage comprising a coil
• CPC Class Codes: H03F 2200/387 A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier
• CPC Class Codes: H03F 2200/391 the output circuit of an amplifying stage comprising an LC-network
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/21 with semiconductor devices only H03F3/245 takes precedence
• CPC Class Codes: H03F 3/2171 with field-effect devices H03F3/2173 - H03F3/2178 take precedence
• CPC Class Codes: H03F 3/2176 Class E amplifiers
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03H 7/38 Impedance-matching networks

Abstract

Described is a phase-switched phase-switched, impedance modulation amplifier (PSIM). The PSIM has an input that can be coupled to a source and an output that can be coupled to a load. The PSIM includes one or more phase-switched reactive elements and a controller. The controller provides a control signal to each of the one or more phase-switched reactive elements. In response to one or more control signals provided thereto, each phase-switched reactive element provides a corresponding selected reactance value such that an impedance presented to an input or output port of an RF amplifier may be varied.

Claims

1. A radio frequency (RF) amplifier system having an input port and an output port, the RF amplifier system comprising:

an RF amplifier having an input port coupled to the input port of the RF amplifier system and having an output port; and

a phase-switched tunable impedance network coupled between the output port of the RF amplifier and an output port of the RF amplifier system, the phase-switched tunable impedance network configured such that in response to input signal provided thereto, the phase-switched tunable impedance network varies an impedance thereof to modulate an impedance presented to the output port of the RF amplifier.

2. The RF amplifier system of claim 1, wherein the phase-switched tunable impedance network comprises one or more phase-switched reactive elements, each of the one or more phase-switched reactive elements configured to receive a respective control signal, and, in response to the respective control signal provided thereto, each phase-switched reactive element is provided having a corresponding desired reactance value.

3. The RF amplifier system of claim 2, further comprising:

a controller configured to provide a respective control signal to each of the one or more phase-switched reactive elements.

4. The RF amplifier system of claim 2, wherein each of the one or more phase-switched reactive elements comprises:

one or more reactive elements;

at least one switch;

wherein at least one of the one or more reactive elements is configured to be switched into and out of the phase-switched tunable impedance network by at least one switch associated therewith.

5. The RF amplifier system of claim 4, wherein the at least one associated switch is operable at a switching frequency related to a frequency of an RF signal at the output port of the RF amplifier and a switching phase based upon the respective control signal.

6. The RF amplifier system of claim 4, wherein the at least one switch is operable in a half-wave switching configuration to switch on and off once per cycle of the RF signal at the output port of the RF amplifier.

7. The RF amplifier system of claim 4, wherein the at least one switch is operable in a full-wave switching configuration to switch on and off twice per cycle of the RF signal at the output port of the RF amplifier.

8. The RF amplifier system of claim 2, wherein each of the one or more phase-switched reactive elements comprises a capacitor in parallel with a switch.

9. The RF amplifier system of claim 8, wherein each of the one or more phase-switched reactive elements further comprises an inductor in series with the combination of the capacitor in parallel with the switch.

10. The RF amplifier system of claim 4, wherein the at least one switch is operable to provide at least one of:

zero voltage switching and zero current switching of said at least one switch.

11. The RF amplifier system of claim 5, wherein the switching frequency and the switching phase are selected to provide the phase-switched reactive element having a desired reactance value.

12. The RF amplifier system of claim 11, wherein at least one of the one or more phase-switched reactive elements is one of:

a capacitive element having a capacitive value, and wherein the capacitance value of the phase-switched capacitive element at a desired frequency is related to a physical DC capacitance value of the phase-switched capacitive element and the switching phase; and

an inductive element having an inductance value, and wherein the inductance value of the phase-switched inductive element at a desired frequency is related to a physical DC inductance value of the phase-switched inductive element and the switching phase.

13. The RF amplifier system of claim 1, wherein the impedance presented to the output port of the RF amplifier by the phase-switched tunable matching network is dynamically adapted to match a variable load impedance coupled to the output port of the RF amplifier system to an impedance of the RF amplifier.

14. The RF amplifier system of claim 13, further comprising an RF load coupled to the output port of the RF amplifier system wherein the RF load is at least one of:

an antenna;

a transmission line; and

a plasma load.

15. The RF amplifier system of claim 4, wherein the RF amplifier comprises a switching inverter comprising at least one switching element configured to generate RF power.

16. The RF amplifier system of claim 12, wherein the controller modulates the impedance of the phase-switched tunable impedance network presented to the output port of the RF amplifier such that the RF amplifier maintains zero-voltage-switching (ZVS) of the at least one switching element of the switching inverter.

17. The RF amplifier system of claim 4, wherein switching the at least one switch of each of the one or more phase-switched reactive elements modulates an impedance transformation provided by the phase-switched tunable impedance network.

18. The RF amplifier system of claim 1 further comprising:

a filter coupled to the phase-switched tunable impedance network, the filter having a filter characteristic that reduces harmonic content generated by the phase-switched tunable impedance network that is presented to at least one of the output port of the RF amplifier and the output port of the RF amplifier system.

19. The RF amplifier system of claim 18, wherein the filter comprises one or more filter components configured to electrically isolate DC signals between the phase-switched tunable impedance network and at least one of the RF amplifier and the output port of the RF amplifier system.

20. The RF amplifier system of claim 1, wherein the phase-switched tunable impedance network comprises:

a first shunt path phase-switched variable reactive element coupled to a first node of a series path reactive element.

21. The RF amplifier system of claim 20, wherein the phase-switched tunable impedance network further comprises:

a second shunt path phase-switched variable reactive element coupled to a second node of the series path reactive element.

22. A method of operating a radio frequency (RF) amplifier system, the method comprising:

providing an RF signal to an input port of an RF amplifier;

amplifying the RF signal by the RF amplifier to provide an amplified RF signal at an output port of the amplifier; and

varying an impedance of a phase-switched tunable impedance network coupled between the output port of the RF amplifier and an output port of the RF amplifier system to modulate an impedance presented to the RF amplifier.

23. The method of claim 22, wherein varying the impedance of the phase-switched tunable impedance network comprises:

receiving a control signal by the phase-switched tunable impedance network; and

in response to the control signal, electrically connecting or disconnecting at least one reactive element into or out of the phase-switched tunable impedance network at a frequency and phase related to a frequency of an RF signal at the output port of the RF amplifier to provide the phase-switched tunable impedance network having a desired reactance value.

24. The method of claim 23, wherein the phase-switched tunable impedance network comprises one or more reactive elements and at least one switch, and wherein electrically connecting or disconnecting at least one reactive element into or out of the phase-switched tunable impedance network comprises:

switching at least one of the one or more reactive elements into and out of the phase-switched tunable impedance network by at least one switch associated therewith; and

operating the at least one associated switch at a switching frequency and a switching phase based upon the respective control signal.

25. The method of claim 24, further comprising:

selecting the switching frequency and the switching phase based upon the frequency of the RF signal at the output port of the RF amplifier to provide the phase-switched reactive element having a desired reactance value.

26. The method of claim 22, further comprising:

dynamically adapting the impedance presented to the RF amplifier by the phase-switched tunable matching network to match a variable load impedance coupled to the output port of the RF amplifier system to an impedance of the RF amplifier.

27. The method of claim 22, wherein modulating the load impedance presented to the RF amplifier by the phase-switched tunable impedance network controls a power level of the amplified signal provided to the output port of the RF amplifier system.

28. The method of claim 24, wherein the amplifier comprises a switching inverter comprising at least one switching element configured to generate RF power, the method further comprising:

maintaining zero-voltage-switching (ZVS) of the at least one switching element of the switching inverter by modulating the impedance of the phase-switched tunable impedance network presented to the RF amplifier.

29. The method of claim 24, further comprising:

switching the at least one switch of the phase-switched tunable impedance network to provide at least one of;

zero voltage switching and zero current switching of said at least one switch.