HIGH VOLTAGE SWITCHING LINEAR AMPLIFIER AND METHOD THEREFOR

• US 20140112024A1
• Filed: 10/23/2012
• Published: 04/24/2014
• Est. Priority Date: 10/23/2012
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Lei, Jimes
• Granted Patent: US 9,225,253 B2
• Time in Patent Office: Days
• US Class Current: 363/17
• CPC Class Codes: H02M 1/0045 Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/33573 Full-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 7/103 Containing passive elements (capacitively coupled) which are ordered in cascade on one source

Abstract

A switching linear amplifier has a DC-DC converter to increase a low input DC voltage to a first high voltage DC. A high voltage high frequency inverter is coupled to the DC-DC converter to generate high voltage pulses. A multistage voltage multiplier is coupled to the high voltage high frequency inverter to generate a second high voltage DC. A controlled charge and discharge circuit is coupled to the multistage voltage multiplier to drive a capacitive load.

Claims

1. A switching linear amplifier comprising:

a DC-DC converter to increase a low input DC voltage to a first high voltage DC;

a high voltage high frequency inverter coupled to the DC-DC converter to generate high voltage pulses;

a multistage voltage multiplier coupled to the high voltage high frequency inverter to generate a second high voltage DC; and

a controlled charge and discharge circuit coupled to the multistage voltage multiplier to drive a capacitive load.

2. The amplifier of claim 1, further comprising a charge pump coupled to the DC-DC converter.

3. The amplifier of claim 1, where the DC-DC converter is comprises:

a MOSFET;

a gate driver for turning on and off the MOSFET;

an inductor coupled to the MOSFET;

a diode coupled to the inductor and the MOSFET; and

a high voltage capacitor coupled to the diode;

wherein the inductor is charged from the low input DC voltage and then discharged through the diode into the high voltage capacitor to generate the first high voltage DC.

4. The amplifier of circuit topology of claim 1, wherein the high voltage high frequency inverter generates two outputs, wherein the two outputs are approximately 180 degrees out of phase with respect to each other.

5. The amplifier of claim 1, wherein the multistage voltage multiplier comprises:

a series of stacked diodes where the last diode goes to a high voltage capacitor;

an individual capacitor connecting to each node of the stacked diodes where an anode and cathode of two diodes are connected together;

wherein the other side of every capacitor are driven by high voltage pulses from the high voltage high frequency inverter.

6. The amplifier of claim 1, wherein the controlled charge and discharge circuit comprises:

a first series stacked N-channel MOSFETs with balancing resistors for a controlled charge; and

a second series of stacked N-channel MOSFETs with balancing resistors for a controlled discharge;

wherein the controlled charge and controlled discharge is controlled by an operational amplifier.

7. The amplifier of claim 1, wherein the controlled charge and discharge circuit comprises a series stacked N-channel MOSFETs with balancing resistors for a controlled discharge, wherein the controlled discharge is controlled by an operational amplifier.

8. The amplifier of claim 1, wherein the controlled charge and discharge circuit comprises:

a first series stacked N-channel MOSFETs with balancing resistors for a controlled charge; and

a second series of stacked N-channel MOSFETs with balancing resistors for a controlled discharge; and

an opto-coupler to allow the output load to have an undefined floating ground.

9. The amplifier of claim 4, wherein the high voltage high frequency inverter comprises a comparator to turn it off when the output voltage is in regulation.

10. The amplifier of claim 4, wherein the high voltage high frequency inverter comprises:

a comparator to turn it off when the output voltage is in regulation; and

a logic gate to turn the comparator on and off at a desired frequency.

11. A switching linear amplifier comprising:

a charge pump to increase a low input DC voltage source for supplying a higher DC voltage for a gate driver;

a DC-DC converter to increase a low input DC voltage to a first high voltage DC and coupled to the charge pump to provide adequate gate drive voltage for increased efficiency;

a high voltage high frequency inverter coupled to the DC-DC converter to generate high voltage pulses, wherein the high voltage high frequency inverter generates two outputs, wherein the two outputs are approximately 180 degrees out of phase with respect to each other;

a multistage voltage multiplier coupled to the high voltage high frequency inverter to generate a second high voltage DC; and

a controlled charge and discharge circuit coupled to the multistage voltage multiplier to drive a capacitive load.

12. The amplifier of claim 11, where the DC-DC converter comprises:

a MOSFET;

a gate driver for turning on and off the MOSFET;

an inductor coupled to the MOSFET;

a diode coupled to the inductor and the MOSFET; and

a high voltage capacitor coupled to the diode;

wherein the inductor is charged from the low input DC voltage and then discharged through the diode into the high voltage capacitor to generate the first high voltage DC.

13. The amplifier of claim 11, wherein the multistage voltage multiplier comprises:

a series of stacked diodes where the last diode goes to a high voltage capacitor;

an individual capacitor connecting to each node of the stacked diodes where an anode and cathode of two diodes are connected together;

wherein the other side of every capacitor are driven by high voltage pulses from the high voltage high frequency inverter.

14. The amplifier of claim 11, wherein the controlled charge and discharge circuit comprises:

a first series stacked N-channel MOSFETs with balancing resistors for a controlled charge; and

a second series of stacked N-channel MOSFETs with balancing resistors for a controlled discharge;

wherein the controlled charge and controlled discharge is controlled by an operational amplifier.

15. The amplifier of claim 11, wherein the controlled charge and discharge circuit comprises a series stacked N-channel MOSFETs with balancing resistors for a controlled discharge, wherein the controlled discharge is controlled by an operational amplifier.

16. The amplifier of claim 11, wherein the controlled charge and discharge circuit comprises:

a first series stacked N-channel MOSFETs with balancing resistors for a controlled charge; and

a second series of stacked N-channel MOSFETs with balancing resistors for a controlled discharge; and

an opto-coupler to allow the output load to have an undefined floating ground.

17. The amplifier of claim 14, wherein the high voltage high frequency inverter comprises a comparator to turn it off when the output voltage is in regulation.

18. The amplifier of claim 14, wherein the high voltage high frequency inverter comprises:

a comparator to turn it off when the output voltage is in regulation; and

a logic gate to turn the comparator on and off at a desired frequency.