Enhanced resonant circuit amplifier

Patent metadata

Field	Value
Publication number	US-10230362-B2
Application number	US-201715482652-A
Country	US
Kind code	B2
Filing date	Apr 7, 2017
Priority date	Dec 23, 2016
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

Techniques for providing an enhanced resonant circuit amplifier are described herein. Using a capacitor to couple the drive to the resonant circuit can be problematic because the current flows the same direction with every energy burst, which causes the coupling capacitor to charge up and stop injecting energy into the resonant circuit. To solve this issue, embodiments disclosed herein add a burst of energy once every half cycle. This reduces distortion in the resonant energy. A second benefit is the ability to “push in” and “pull out” energy from the resonant circuit, which can prevent the capacitor from charging up and allow a resonant circuit amplifier to continually produce a symmetric, stable output. In addition, a controller can dynamically modify a number of aspects of an output, e.g., an amplitude and/or a DC bias, by modifying the duty cycle of an input signal.

First claim

What is claimed is:

1. A system, comprising:
a resonant circuit comprising an input and an output, the resonant circuit generating an amplified output signal at a predetermined frequency in response to receiving an intermediate signal received at the input of the resonant circuit, wherein the resonant circuit generates the amplified output signal by amplifying the intermediate signal;
a filter comprising an input and an output, wherein the output of the filter is coupled to the input of the resonant circuit, wherein the filter reduces harmonic frequencies above the predetermined frequency from an input signal received at the input of the filter, the output of the filter producing the intermediate signal at the predetermined frequency and having reduced harmonic frequencies above the predetermined frequency;
a first switch coupling a first source at a first voltage to the input of the filter when an input of the first switch is activated;
a second switch coupling a second source at a second voltage to the input of the filter when an input of the second switch is activated; and
a controller generating control signals to alternately activate the input of the first switch and the input of the second switch at the predetermined frequency associated with a cycle, where the first switch is activated at the beginning of the cycle and the second switch is activated at a middle of the cycle, wherein a duty cycle of the control signals are less than a half of the cycle, wherein an alternating activation of the first switch and the second switch at the predetermined frequency produces the intermediate signal having the predetermined frequency, the intermediate signal causing the resonant circuit to resonate at the predetermined frequency thereby causing a generation of the amplified output signal at the predetermined frequency, wherein the controller causes a duty cycle (d 1 ) of a control signal for activating the first switch to be equal to a duty cycle (d 2 ) of a control signal for activating the second switch.

2. The system of claim 1 , wherein the resonant circuit comprises a capacitor (C 1 ) and an inductor (L 1 ) having capacitance and inductance values for causing resonation of the intermediate signal to generate the amplified output signal at the predetermined frequency.

3. The system of claim 2 , wherein the capacitor and the inductor are coupled in series, wherein a first terminal of the inductor (L 1 ) functions as the input of the resonant circuit, wherein a second terminal of the inductor (L 1 ) is coupled to an output node, wherein a first terminal of the capacitor (C 1 ) is coupled to the output node, and wherein a second terminal of the capacitor (C 1 ) is coupled to the second source.

4. The system of claim 2 , wherein the capacitor and the inductor are coupled in series, wherein a first terminal of the capacitor (C 1 ) functions as the input of the resonant circuit, wherein a second terminal of the capacitor (C 1 ) is coupled to an output node, wherein a first terminal of the inductor (L 1 ) is coupled to the output node, and wherein a second terminal of the inductor (L 1 ) is coupled to the second source.

5. The system of claim 2 , wherein the intermediate signal causes the inductor (L 1 ) to generate a magnetic field oscillating at the at the predetermined frequency.

6. The system of claim 3 , wherein the controller modifies the duty cycle (d 1 ) of the control signal for activating the first switch to be greater than the duty cycle (d 2 ) of the control signal for activating the second switch causing a DC voltage of the output node to bias toward the first voltage of the first source.

7. The system of claim 3 , wherein the controller modifies the duty cycle (d 1 ) of the control signal for activating the first switch to be less than the duty cycle (d 2 ) of the control signal for activating the second switch causing a DC voltage of the output node to bias toward the second voltage of the second source.

8. The system of claim 1 , wherein the controller increases the duty cycle (d 1 and d 2 ) of the control signals to increase a gain level of the resonant circuit thereby increasing an amplitude of the amplified output signal, wherein the controller decreases the duty cycle (d 1 and d 2 ) of the control signals to decrease the gain level of the resonant circuit thereby decreasing the amplitude of the amplified output signal.

9. A method for generating an amplified output signal at a predetermined frequency, wherein the method comprises:
generating, at a controller, control signals for alternately activating an input of a first switch and an input of a second switch at the predetermined frequency, wherein the first switch is activated at the beginning of a cycle and the second switch is activated at a middle of the cycle, wherein a duty cycle of the control signals are less than a half of the cycle, wherein the first switch couples a first source at a first voltage to an input of a filter when the first switch is activated wherein the second switch couples a second source at a second voltage to the input of the filter when the second switch is activated;
generating, at the filter, an intermediate signal having the predetermined frequency resulting from the alternately activating of the controller, the intermediate signal having reduced harmonic frequencies above the predetermined frequency, wherein the intermediate signal is provided to an input of a resonant circuit; and
generating, at the resonant circuit, the amplified output signal at the predetermined frequency, wherein the intermediate signal causes the resonant circuit to resonate at the predetermined frequency thereby producing the amplified output signal at the predetermined frequency.

10. The method of claim 9 , further comprising:
receiving, at the controller, a feedback input signal from a device measuring an amplitude of the amplified output signal;
determining, at the controller, that the amplitude is below a threshold; and
based at least in part on determining that the amplitude is below the threshold, increasing the duty cycle of the control signals to increase the amplitude of the amplified output signal.

11. The method of claim 9 , further comprising:
receiving, at the controller, a feedback input signal from a device measuring an amplitude of the amplified output signal;
determining, at the controller, that the amplitude is above a threshold; and
based at least in part on determining that the amplitude is above the threshold, decreasing the duty cycle of the control signals to decrease the amplitude of the amplified output signal.

12. The method of claim 9 , further comprising:
receiving, at the controller, a feedback input signal from a device measuring a current of the amplified output signal;
determining, at the controller, that the current is below a threshold; and
based at least in part on determining that the current is below the threshold, increasing the duty cycle of the control signals to increase the current.

13. The method of claim 9 , further comprising:
receiving, at the controller, a feedback input signal from a device measuring a current of the amplified output signal;
determining, at the controller, that the current is above a threshold; and
based at least in part on determining that the current is above the threshold, decreasing the duty cycle of the control signals to decrease the current.

14. The method of claim 9 , further comprising:
receiving, at the controller, a feedback input signal from a device measuring a magnetic field of the resonant circuit;
determining, at the controller, that an intensity of the magnetic field

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Champion Mark
• Cherkashin Lev
• Dutra Jonathan Alan
• Filer Eric P

Classifications

• H03K7/08 Primary

  Duration or width modulation {; Duty cycle modulation} · CPC title