RF generator with voltage regulator

• US 7,307,475 B2
• Filed: 05/26/2005
• Issued: 12/11/2007
• Est. Priority Date: 05/28/2004
• Status: Active Grant

• Current Assignee: Littelfuse Incorporated
• Original Assignee: IXYS Corporation (Littelfuse Incorporated)
• Inventors: Coleman, Charles
• Primary Examiner(s): NGUYEN, KHANH V
• Application Number:
  US11/140,493
• Publication Number:
  US 20050270097A1
• Time in Patent Office: 929 Days
• Field of Search: None
• US Class Current: 330/251
• CPC Class Codes: H01L 23/473 by flowing liquids H01L23/4332, H01L23/4338 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• CPC Class Codes: H05K 7/20927 Liquid coolant without phase change

Abstract

A radio frequency (RF) generator includes a first half bridge including first and second power transistors; a second half bridge including first and second power transistors; an output node coupling the first and second half bridges and RF signals to a load; positive and negative rails coupled to an AC power source via a rectifier; a first blocking capacitor provided between the positive rail and the load; a second blocking capacitor provided between the negative rail and the load; and a voltage regulator configured to output a given voltage to the first and second bridges, wherein the first and second blocking capacitors are configured to isolate the load from the AC power source.

Claims

1. A radio frequency (RF) generator, comprising:

a first half bridge including first and second power transistors;

a second half bridge including first and second power transistors;

an output node coupling the first and second half bridges and RF signals to a load;

positive and negative rails coupled to an AC power source via a rectifier;

a first blocking capacitor provided between the positive rail and the load;

a second blocking capacitor provided between the negative rail and the load; and

an offline voltage regulator configured to output a given voltage to the first and second bridges,

wherein the first and second blocking capacitors are configured to isolate the load from the AC power source, so that the first and second half bridges do not require a variable, isolated DC power supply.

2. The RE generator of claim 1, wherein the voltage regulator is a step-up or step-down regulator, where the first and second power transistors are MOSFETs, and the third and fourth power transistors are MOSFETs.

3. The RF generator of claim 1, wherein the voltage regulator is provided between the AC power source and the first and second half bridges, where the RF generator is configured to operate at an Industrial Scientific and Medical (ISM) frequency.

4. The RF generator of claim 3, wherein the RF generator is configured to operate at 13.56 MHz or 27.12 MHz.

5. The RF generator of claim 3, wherein the voltage regulator receives power from the AC power source.

6. The RF generator of claim 1, further comprising:

a resonant circuit provided between the first and second half bridges.

7. The RF generator of claim 6, wherein resonant circuit includes first, second, and third inductors.

8. The RF generator of claim 1, further comprising:

a plurality of gate drivers to drive the first and second half bridges;

a controller to control the gate drivers; and

a sensor provided between the first and second bridges and the load, the sensor being configured to determined the power level of signals output by the first and second half bridges and send a feedback signal to the controller.

9. The RF generator of claim 1, further comprising:

a matching network provided between the resonant circuit and the load.

10. The RF generator of claim 1, further comprising:

a third blocking capacitor provided between the positive rail and the load.

11. The RF generator of claim 10, further comprising:

a resonant circuit provided between the first and second half bridges, wherein the first and third blocking capacitors are part of the resonant circuit.

12. The RF generator of claim 11, wherein the first blocking capacitor is proximate the first half bridge, and the second blocking capacitor is proximate the second half bridge.

13. The RF generator of claim 12, wherein the first and second blocking capacitors have substantially the same capacitance.

14. The RF generator of claim 1, wherein the voltage regulator is a step-up or step-down regulator that outputs a fixed voltage.

15. A radio frequency (RF) generator, comprising:

a first half bridge including first and second power transistors;

a second half bridge including first and second power transistors;

an output node coupling the first and second half bridges and RF signals to a load;

positive and negative rails coupled to an AC power source via a rectifier;

a first blocking capacitor provided between the positive rail and the load;

a second blocking capacitor provided between the negative rail and the load; and

an offline voltage regulator configured to output a fixed voltage to the first and second half bridges,

wherein the first and second blocking capacitors are configured to isolate the load from the AC power source, so that the first and second half bridges do not require a variable, isolated DC power supply,

wherein the voltage regulator is configured to raise or lower voltage output to the first and second half bridges during a brownout condition.

16. The RF generator of claim 15, further comprising:

a plurality of gate drivers to drive the first and second half bridges;

a controller to control the gate drivers; and

a sensor provided between the first and second bridges and the load, the sensor being configured to determined the power level of signals output by the first and second half bridges and send a feedback signal to the controller.

17. The RF generator of claim 15, wherein the voltage regulator receives AC currents from the AC power source.

18. The RF generator of claim 15, further comprising:

a third blocking capacitor provided between the positive rail and the load.