High efficiency amplifier and method of designing same

• US 20040189381A1
• Filed: 03/05/2004
• Published: 09/30/2004
• Est. Priority Date: 03/28/2003
• Status: Active Grant

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew Corporation (CommScope Holding Company, Inc.)
• Inventors: Louis, Edward Vincent
• Granted Patent: US 7,064,606 B2
• Time in Patent Office: Days
• US Class Current: 330/124R
• CPC Class Codes: H03F 1/0266 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/0288 using a main and one or several auxiliary peaking amplifiers whereby the load is connected to the main amplifier using an impedance inverter, e.g. Doherty amplifiers
• CPC Class Codes: H03F 2200/18 the bias of the gate of a FET being controlled by a control signal
• CPC Class Codes: H03F 2200/198 A hybrid coupler being used as coupling circuit between stages of an amplifier circuit
• CPC Class Codes: H03F 3/602 Combinations of several amplifiers

Abstract

An amplifier includes a main amplifier circuit and at least one auxiliary amplifier circuit. Portions of an RF signal to be amplified are delivered to the main and auxiliary amplifiers. The auxiliary amplifier circuit is selectively operable to operate in combination with the main amplifier circuit, such as based on the level of the RF signal. At least one hybrid coupler circuit has input ports coupled with outputs of the main amplifier circuit and auxiliary amplifier circuit. The hybrid coupler circuit is operable to combine amplifier circuit output signals at a coupler first output port. A coupler second output port is terminated with one of an electrical short and an electrical open circuit.

Claims

1. An amplifier comprising:

a main amplifier circuit;

at least one auxiliary amplifier circuit, the auxiliary amplifier circuit being selectively operable to operate in combination with the main amplifier circuit;

at least one hybrid coupler circuit having an output port and an isolation port and coupled to combine output signals of the amplifiers at the coupler output port;

the amplifier circuits having associated reflection coefficients at their outputs;

a termination coupled at the isolation port of the coupler circuit, the termination configured to have a reflection coefficient based upon the reflection coefficient at the output of the amplifier circuits.

2. The amplifier of claim 1 further comprising a matching network proximate an amplifier circuit output, the reflection coefficient of the amplifier circuit output being a function of the matching network.

3. The amplifier of claim 1 further comprising a phasing line proximate an amplifier circuit output, the reflection coefficient of the amplifier circuit output being a function of the phasing line.

4. The amplifier of claim 1 wherein the termination is configured by terminating a length of transmission line with one of an electrical short circuit and an electrical open circuit.

5. The amplifier of claim 1 wherein the termination is configured so the reflection coefficient of the termination is based upon the reflection coefficient at the output of the amplifier circuits according the following relationship:

ang(_Y)=180°

−

ang(_out)

6. The amplifier of claim 1 wherein the termination is configured so the reflection coefficient of the termination is based upon the reflection coefficient at the output of the amplifier circuits according the following relationship:

ang(_Y)=−

ang(_out)

7. The amplifier of claim 4 wherein the termination is configured by terminating a length of transmission line with an electrical open circuit so the reflection coefficient of the termination has an angle according to the following relationship:

ang(_Y)=−

2θ

_OC

wherein θ

_OC is the electrical length in degrees of an open circuited transmission line.

8. The amplifier of claim 4 wherein the termination is configured by terminating a length of transmission line with an electrical short circuit so the reflection coefficient of the termination has an angle according to the following relationship:

ang(_Y)=180−

2θ

_SC

wherein θ

_SC is the electrical length in degrees of a short circuited transmission line.

9. The amplifier of claim 4 wherein the length of the transmission line for the termination includes a length of transmission line internal to the hybrid coupler circuit.

10. The amplifier of claim 1 wherein the reflection coefficient presented to the isolation port has an angle that is a function of the angle of the output reflection coefficient of the amplifier.

14. The amplifier of claim 1 wherein the termination is configured by terminating a length of transmission line with one of an electrical short circuit and an electrical open circuit.

17. The amplifier of claim 14 wherein the termination is configured by terminating a length of transmission line with an electrical open circuit so the reflection coefficient of the termination has an angle according to the following relationship:

ang(_Y)=−

2θ

_OC

wherein θ

_OC is the electrical length in degrees of an open circuited transmission line.

18. The amplifier of claim 14 wherein the termination is configured by terminating a length of transmission line with an electrical short circuit so the reflection coefficient of the termination has an angle according to the following relationship:

ang(_Y)=180−

2θ

_SC

wherein θ

_SC is the electrical length in degrees of a short circuited transmission line.

19. The amplifier of claim 14 wherein the length of the transmission line for the termination includes a length of transmission line internal to the hybrid coupler circuit.

11. An amplifier comprising:

a plurality of amplifier circuits having associated reflection coefficients at their outputs;

at least one hybrid coupler circuit having an output port and an isolation port and coupled to combine output signals of the amplifier circuits at the coupler output port;

a termination coupled at the isolation port of the coupler circuit, the termination configured to have a reflection coefficient based upon the reflection coefficient at the output of the amplifier circuits.

12. The amplifier of claim 11 further comprising a matching network proximate an amplifier circuit output, the reflection coefficient of the amplifier output being a function of the matching network.

13. The amplifier of claim 11 further comprising a phasing line proximate an amplifier circuit output, the reflection coefficient of the amplifier output being a function of the phasing line.

15. The amplifier of claim 11 wherein the termination is configured so the reflection coefficient of the termination is based upon the reflection coefficient at the output of the amplifier circuits according the following relationship:

ang(_Y)=180°

−

ang(_out)

16. The amplifier of claim 11 wherein the termination is configured so the reflection coefficient of the termination is based upon the reflection coefficient at the output of the amplifier circuits according the following relationship:

ang(_Y)=−

ang(_out)

20. The amplifier of claim 11 wherein the reflection coefficient presented to the isolation port has an angle that is a function of the angle of the output reflection coefficient of the amplifier.

21. A method of configuring an amplifier comprising:

combining output signals of a main amplifier circuit and at least one auxiliary amplifier circuit with at least one hybrid coupler circuit having an output port and an isolation port, and providing an output at an output port of the coupler circuit;

the main and auxiliary amplifier circuits having associated reflection coefficients at their outputs;

coupling a termination at the isolation port of the coupler circuit;

configuring the termination to have a reflection coefficient based upon the reflection coefficient at the output of the amplifier circuits.

22. The method amplifier of claim 21 further comprising coupling a matching network proximate to an amplifier output, the reflection coefficient of the amplifier output being a function of the matching network.

23. The method of claim 21 further comprising coupling a phasing line proximate to an amplifier output, the reflection coefficient of the amplifier output being a function of the phasing line.

24. The method of claim 21 wherein configuring the termination includes terminating a length of transmission line with one of an electrical short circuit and an electrical open circuit.

25. The method of claim 21 comprising configuring the termination so the reflection coefficient of the termination is based upon the reflection coefficient at the output of the amplifier circuits according the following relationship:

ang(_Y)=180°

−

ang(_out)

26. The method of claim 21 comprising configuring the termination so the reflection coefficient of the termination is based upon the reflection coefficient at the output of the amplifier circuits according to the following relationship:

ang(_Y)=−

ang(_out)

27. The method of claim 24 comprising configuring the termination by terminating a length of transmission line with an electrical open circuit so the reflection coefficient of the termination has an angle according to the following relationship:

ang(_Y)=−

2θ

_OC

wherein θ

OC is the electrical length in degrees of an open circuited transmission line.

28. The method of claim 24 comprising configuring the termination by terminating a length of transmission line with an electrical short circuit so the reflection coefficient of the termination has an angle according to the following relationship:

ang(_Y)=180−

2θ

_SC

wherein θ

_SC is the electrical length in degrees of a short circuited transmission line.

29. The method of claim 24 wherein the length of the transmission line for the termination includes a length of transmission line internal to the hybrid coupler circuit.

30. The method of claim 21 wherein the reflection coefficient presented to the isolation port has an angle that is a function of the angle of the output reflection coefficient of the amplifier.