Power amplifier

• US 20070046371A1
• Filed: 08/31/2005
• Published: 03/01/2007
• Est. Priority Date: 08/31/2005
• Status: Active Grant

• Current Assignee: Morpho Detection (Safran SA)
• Original Assignee: GE Homeland Protection Incorporated (Safran SA)
• Inventors: Crowley, Christopher, Turner, Peter, Barabash, Leonid
• Granted Patent: US 7,362,182 B2
• Time in Patent Office: Days
• US Class Current: 330/195
• CPC Class Codes: G01R 33/3614 RF power amplifiers
• CPC Class Codes: G01R 33/441 Nuclear Quadrupole Resonance [NQR] Spectroscopy and Imaging
• CPC Class Codes: H03F 2200/541 Transformer coupled at the output of an amplifier
• CPC Class Codes: H03F 2203/21142 Output signals of a plurality of power amplifiers are parallel combined to a common output
• CPC Class Codes: H03F 2203/21145 Output signals are combined by switching a plurality of paralleled power amplifiers to a common output
• CPC Class Codes: H03F 2203/21175 An output signal of a power amplifier being on/off switched
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602

Abstract

A radio frequency power amplifier including control electronics for providing control signals for timing of the power amplifier. A first group of the drivers are coupled to the control electronics and a second group of drivers are coupled to the control electronics. The first group of drivers operate in response to the control signals to generate first drive signals and the second group of drivers operate in response to the control signals to generate second drive signals with a phase difference of 180° relative to the first drive signals. A first group of switches energize a first group of primary windings in response to the first drive signals and a second group of switches energize a second group of primary windings in response to the second drive signals. An output summing transformer has a plurality of ferrite cores, the first group of primary windings and the second group of primary windings passing through the ferrite cores. A secondary output winding for connection with a load passes through the ferrite cores of the output summing transformer.

Claims

1. A radio frequency power amplifier comprising:

a control electronics providing control signals for timing of the power amplifier;

a first group of the drivers coupled to the control electronics and a second group of drivers coupled to the control electronics, the first group of drivers operating in response to the control signals to generate first drive signals, the second group of drivers operating in response to the control signals to generate second drive signals with a phase difference of 180°

relative to the first drive signals;

a first group of switches energizing a first group of primary windings in response to the first drive signals, a second group of switches energizing a second group of primary windings in response to the second drive signals;

an output-summing transformer having a plurality of ferrite cores, the first group of primary windings and the second group of primary windings passing through the ferrite cores;

a secondary output winding for connection with a load, the secondary output winding passing through the ferrite cores of the output summing transformer.

2. The power amplifier of claim 1 further comprising:

a number of Q-damper transistors coupled to a secondary damping winding, the secondary damping winding passing through the ferrite cores for reducing the Q of the amplifier load between transmit pulses.

3. The power amplifier of claim 2 wherein the power amplifier operates in A, B, C, D, E, F and S modes.

4. The power amplifier of claim 1 wherein the first group of switches include first transistors having a first terminal coupled to the first primary winding and a second terminal coupled to ground, the second group of switches include second transistors having a first terminal couple to the second primary winding and a second terminal coupled to ground.

5. The power amplifier of claim 4 wherein the first primary winding is coupled to a power supply and the second primary winding is coupled to the power supply.

6. The power amplifier of claim 4 wherein the first transistors have a gate terminal coupled to first transient voltage suppressors and the second transistors have a gate terminal coupled to second transient voltage suppressors.

7. The power amplifier of claim 1 wherein the first group of primary windings pass through the ferrite cores in a first direction and the second group of primary windings pass through the ferrite cores in a second direction opposite the first direction

8. The power amplifier of claim 1 wherein the ferrite cores are toroids, the first group of primary windings and the second group of primary windings passing through the toroid center in opposite directions.

16. The power amplifier of claim 1 wherein the signals from the different stages are delayed to compensate the propagation time of the signals in the output summing transformer.

9. An output summing transformer comprising:

ferrite cores, where a number of ferrite cores is equal to a number of the stages of a power amplifier;

a first group of primary windings passing through the ferrite cores and a second group of primary windings passing through the ferrite cores;

a secondary output winding passing through the ferrite cores for connection with a load;

a secondary damping winding passing through the ferrite cores,

a number of Q-damper transistors coupled to the secondary damping winding for reducing the Q of the amplifier load between transmit pulses.

10. The output summing transformer of claim 9 wherein the first group of primary windings pass through the ferrite cores in a first direction and the second group of primary windings pass through the ferrite cores in a second direction opposite the first direction

11. The output summing transformer of claim 9 wherein the ferrite cores are toroids, the first group of primary windings and the second group of primary windings passing through the toroid center in opposite directions.

12. The output summing transformer of claim 9 wherein windings in the first group of primary windings have a first terminal for connection to a power supply and a second terminal for connection to a first switch, windings in the second group of primary windings have a first terminal for connection to a power supply and a second terminal for connection to a second switch.

13. The output summing transformer of claim 9 wherein the secondary output winding has a shape of a coaxial cable, the secondary output winding including an outer cylindrical electrode connected by an end plate with a central electrode.

14. The output summing transformer of claim 13 wherein the central electrode passes through the ferrite cores.

15. The output summing transformer of claim 14 wherein connection to the load is made with the central electrode at an open end opposite the end plate.