RF generator with reduced size and weight

• US 7,259,623 B2
• Filed: 05/27/2005
• Issued: 08/21/2007
• 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): Pascal; Robert
• Assistant Examiner(s): NGUYEN, HIEU P
• Application Number:
  US11/140,404
• Publication Number:
  US 20050275456A1
• Time in Patent Office: 816 Days
• Field of Search: 330/251, 315/209
• 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 comprises 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 a power source; 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 rectification circuit configured receive an alternating current (AC) from an AC power source and output a direct current (DC) 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 module, 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 a power source;

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

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

an offline rectification circuit configured to receive an alternating current (AC) from an AC power source and output a direct current (DC) to the first and second bridges;

a resonant circuit provided between the first and second half bridges, the resonant circuit including first, second, and third inductors,

wherein the first and second blocking capacitors are configured to isolate the load from the AC power source.

2. The RF generator module of claim 1, further comprising:

a heatsink including first, second, and third plates, the second plate provided between the first and third plates and having a solid portion and a hollow portion, the hollow portion of the second plate defining a coolant area,

wherein the power source is the AC power source, and

wherein the positive and negative rails are coupled to the AC power source via the rectification circuit.

3. The RF generator module of claim 2, wherein the first, second, and third plates of the heatsink all comprise conductive materials.

4. The RF generator module of claim 2, wherein the second plate is a punched plate.

5. The RF generator module of claim 2, wherein a ratio of an area defined by the hollow portion and an area defined by the solid portion is at least 2:

1, whereby the heatsink is configured to have a reduced weight.

8. The RF generator of claim 1, wherein the DC output by the rectification circuit is applied to the first and second half bridges directly, so that only a single conversion of DC to RF is performed, where the first and second power transistors are MOSFETs, and the third and fourth power transistors are MOSFETs.

9. The RF generator of claim 1, wherein the rectification circuit 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.

10. 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.

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

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

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

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

6. A radio frequency (RF) generator module, 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 a power source;

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

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

an offline rectification circuit configured to receive an alternating current (AC) from an AC power source and output a direct current (DC) to the first and second bridges; and

an offline voltage regulator configured to output a given voltage to the first and second half bridges, the voltage regulator being coupled to the rectifier,

wherein the first and second blocking capacitors are configured to isolate the load from the AC power source.

7. The RF generator module of claim 6, wherein the voltage regulator is a boost regulator or a buck regulator.

13. A radio frequency (RF) generator module, 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 a power source;

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

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

an offline rectification circuit configured to receive an alternating current (AC) from an AC power source and output a direct current (DC) to the first and second bridges; and

a heatsink including first, second, and third plates, the second plate provided between the first and third plate having a solid portion and a hollow portion, the hollow portion of the second plate defining a coolant area,

wherein the first and second blocking capacitors are configured to isolate the load from the AC power source.

14. The RF generator module of claim 13, wherein the power source is the AC power source, and positive and negative rails are coupled to the AC power source via the rectification circuit.

15. The RF generator module of claim 13, further comprising:

an offline voltage regulator configured to output a given voltage to the first and second half bridges, the voltage regulator being coupled to the rectifier.

16. The RF generator module of claim 15, wherein the voltage regulator is a boost regulator or a buck regulator.

17. A radio frequency (RF) generator module, 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 a power source;

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

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

an offline rectification circuit configured to receive an alternating current (AC) from an AC power source and output a direct current (DC) to the first and second bridges;

a heatsink including first, second, and third plates, the second plate provided between the first and third plates and having a solid portion and a hollow portion, the hollow portion of the second plate defining a coolant area; and

a voltage regulator coupled to the rectification circuit and is configured to provide a given 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, and

wherein the RF generator module is configured to control output power to the load by controlling phase displacements of the power transistors.

18. The RF generator module of claim 17, wherein the power transistors are MOSFETs.