Reconfigurable power amplifier for improved low-power efficiency

Patent metadata

Field	Value
Publication number	US-9190962-B2
Application number	US-201414324863-A
Country	US
Kind code	B2
Filing date	Jul 7, 2014
Priority date	Apr 18, 2012
Publication date	Nov 17, 2015
Grant date	Nov 17, 2015

Abstract

A radio frequency (RF) power amplifier (PA) is reconfigured to operate in a low power mode from a high power mode. The RF PA has a first RF amplifier is connected to the first and second inputs of a first transformation network. The RF PA has a second a second RF amplifier connected to a second transformation network. During high power mode, both RF amplifiers drive a load coupled to the transformation networks. In low power mode the first RF amplifier is disabled and the first and second inputs of the first transformation are coupled together so as to change the load impedance seen by the second RF amplifier. The second RF amplifier continues to supply power to the load during operation in the low power mode.

First claim

What is claimed is:

1. A reconfigurable power amplifier comprising:
a first transformation network including a first inductor coupled between a first input and an output, a first capacitor coupled between a second input and the output, and a third capacitor coupled between the first input and a supply node;
a second transformation network including a second capacitor coupled between a third input and the output, a second inductor coupled between a fourth input and the output, and a fourth capacitor coupled between the fourth input and a ground node;
wherein said first and second transformation networks are coupled together to drive a load;
a first radio frequency (RF) amplifier coupled to the first and second inputs of the first transformation network;
a second RF amplifier coupled to the third and fourth inputs of the second transformation network,
wherein in a first mode of operation the first and second RF amplifiers contribute RF power to the load;
a first circuit to disable the first RF amplifier so that it does not contribute RF power to the load in a reconfigured mode of operation; and
a second circuit to couple said first and second inputs of the first transformation network together in the reconfigured mode of operation.

2. The reconfigurable power amplifier of claim 1 wherein the second RF amplifier is operable to provide power to the load in the reconfigured mode of operation.

3. The reconfigurable power amplifier of claim 1 wherein the reconfigured mode of operation is a lower power mode than the first mode of operation.

4. The reconfigurable power amplifier of claim 1
wherein said first RF amplifier comprises
a first transistor coupled to said first input of the first transformation network and
a second transistor coupled to said second input of the first transformation network; and

wherein said second RF amplifier comprises
a third transistor coupled to said third input of the second transformation network and
a fourth transistor coupled to said fourth input of the second transformation network.

5. The reconfigurable power amplifier of claim 1 wherein said second circuit to couple said first and second inputs of the first transformation network comprises a capacitor coupled to the first and second inputs of the first transformation network in the reconfigured mode of operation so as to create an RF ground.

6. The reconfigurable power amplifier of claim 1 wherein said first RF amplifier is disabled by placing transistors of the first RF amplifier in a high impedance state.

7. The power amplifier of claim 1 wherein said second circuit to couple said first and second inputs of the first transformation network comprises a capacitor coupled between said first and second inputs of the first transformation network in the reconfigured mode of operation.

8. A power amplifier operable in a first mode and a second mode, comprising:
a first transformation network including first and second inputs and an output for driving a load;
a second transformation network including third and fourth inputs and an output coupled to the output of the first transformation network;
a first radio frequency amplifier coupled to the first and second inputs of the first transformation network;
a second radio frequency amplifier coupled to the third and fourth inputs of the second transformation network;
a third inductor coupled between the first input of the first transformation network and the second input of the first transformation network;
a fourth inductor coupled between the first input of the first transformation network and the second input of the first transformation network; and
a fifth inductor coupled between an intermediate point of the third inductor and an intermediate point of the fourth inductor,
wherein, in the first mode of operation, the first and second radio frequency amplifiers contribute radio frequency power to the load, and
wherein, in the second mode of operation, the first radio frequency amplifier does not contribute radio frequency power to the load and the first and second inputs of the first transformation network are coupled together.

9. The power amplifier of claim 8 , wherein, in the second mode of operation, the second radio frequency amplifier is operable to provide power to the load.

10. The power amplifier of claim 8 ,
wherein the first transformation network comprises a first inductor coupled between the first input and the output and a first capacitor coupled between the second input and the output; and
wherein the second transformation network comprises a second capacitor coupled between the third input and the output and a second inductor coupled between the fourth input and the output.

11. The power amplifier of claim 10 ,
wherein the first transformation network further comprises a third capacitor coupled between the first input and a supply node; and
wherein the second transformation network further comprises a fourth capacitor coupled between the fourth input and a ground node.

12. The power amplifier of claim 8 ,
wherein the first radio frequency amplifier comprises
a first transistor coupled between the first input of the first transformation network and a supply node, and
a second transistor coupled between the second input of the first transformation network and a ground node; and

wherein the second radio frequency amplifier comprises
a third transistor coupled between the third input of the second transformation network and the supply node, and
a fourth transistor coupled between the fourth input of the second transformation network and the ground node.

13. The power amplifier of claim 12 , wherein, in the second mode of operation, the first transistor and the second transistor of the first radio frequency amplifier are switched to high impedance states.

14. The power amplifier of claim 8 ,
wherein the first radio frequency amplifier comprises
a first transistor coupled between the first input of the first transformation network and a supply node, and
a second transistor coupled between the second input of the first transformation network and the supply node; and

wherein the second radio frequency amplifier comprises
a third transistor coupled between the third input of the second transformation network and a ground node, and
a fourth transistor coupled between the fourth input of the second transformation network and the ground node.

15. The power amplifier of claim 14 , wherein, in the second mode of operation, the first transistor and the second transistor of the first radio frequency amplifier are switched fully on.

16. The power amplifier of claim 8 ,
wherein the first radio frequency amplifier comprises
a first transistor coupled between the first input of the first transformation network and a ground node, and
a second transistor coupled between the second input of the first transformation network and the ground node; and

wherein the second radio frequency amplifier comprises
a third transistor coupled between the third input of the second transformation network and a supply node, and
a fourth transistor coupled between the fourth input of the second transformation network and the supply node.

17. The power amplifier of claim 16 , wherein, in the second mode of operation, the first transistor and the second transistor of the first radio frequency amplifier are switched fully on.

18. The power amplifier of claim 8 , wherein, in the second mode of operation, a capacitor is coupled to the first and second inputs of the first transformatio

Assignees

• Black Sand Technologies Inc
• Qualcomm Inc

Inventors

• Paul Susanne A
• Goldenberg Marius

Classifications

• H03F2200/387

  A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier · CPC title

• H03F3/211

  using a combination of several amplifiers (H03F3/60 takes precedence) · CPC title

• H03F2203/21139

  An impedance adaptation circuit being added at the output of a power amplifier stage · CPC title

• H03F2200/255

  Amplifier input adaptation especially for transmission line coupling purposes, e.g. impedance adaptation · CPC title

• H04B1/1607

  Supply circuits (converters H02M; filters therefor H02M1/14; voltage stabilisers G05F1/46) · CPC title