Efficient wide bandwidth envelope tracking power supply

Patent metadata

Field	Value
Publication number	US-10122323-B2
Application number	US-201715477246-A
Country	US
Kind code	B2
Filing date	Apr 3, 2017
Priority date	Apr 4, 2016
Publication date	Nov 6, 2018
Grant date	Nov 6, 2018

Abstract

An envelope tracking power supply, which includes a parallel amplifier, switching circuitry, and a parallel switching supply, is disclosed. The envelope tracking power supply provides an envelope power supply signal to a load. The parallel amplifier regulates an envelope power supply voltage of the envelope power supply signal based on a setpoint of the envelope power supply voltage. The switching circuitry at least partially provides the envelope power supply signal via a first inductive element and drives an output current from the parallel amplifier toward zero. The parallel switching supply provides an assist current to further drive the output current from the parallel amplifier toward zero based on an estimate of a current in the first inductive element and an estimate of a current in the load.

First claim

What is claimed is:

1. An envelope tracking power supply configured to provide an envelope power supply signal to a load via an envelope power supply output, and comprising:
a parallel amplifier having a parallel amplifier output and configured to regulate an envelope power supply voltage of the envelope power supply signal based on a setpoint of the envelope power supply voltage;
switching circuitry configured to at least partially provide the envelope power supply signal via a first inductive element and drive an output current from the parallel amplifier toward zero;
a parallel switching supply having a parallel switching supply output and configured to provide an assist current to further drive the output current from the parallel amplifier toward zero based on an estimate of a current in the first inductive element and an estimate of a current in the load; and
an offset capacitive element coupled between the parallel amplifier output and the envelope power supply output and coupled between the parallel switching supply output and the envelope power supply output.

2. The envelope tracking power supply of claim 1 wherein a switching supply comprises the switching circuitry and the first inductive element, such that a bandwidth of the parallel amplifier is greater than a bandwidth of the parallel switching supply and the bandwidth of the parallel switching supply is greater than a bandwidth of the switching supply.

3. The envelope tracking power supply of claim 2 wherein the bandwidth of the switching supply is less than 8 megahertz, the bandwidth of the parallel switching supply is less than 40 megahertz, and the bandwidth of the parallel amplifier is greater than 40 megahertz.

4. The envelope tracking power supply of claim 1 wherein a switching supply comprises the switching circuitry and the first inductive element, which is coupled between the switching circuitry and the envelope power supply output, such that the envelope tracking power supply is further configured to provide the envelope power supply signal via the envelope power supply output.

5. The envelope tracking power supply of claim 1 wherein the parallel switching supply output is directly coupled to the parallel amplifier output.

6. The envelope tracking power supply of claim 1 further comprising an offset capacitance voltage control loop coupled across the offset capacitive element and configured to regulate a voltage across the offset capacitive element.

7. The envelope tracking power supply of claim 1 wherein the load comprises a radio frequency (RF) power amplifier (PA) configured to receive and amplify an RF input signal to provide an RF transmit signal using the envelope power supply signal.

8. The envelope tracking power supply of claim 1 further comprising an ancillary switching supply configured to provide operating power to the parallel amplifier and the parallel switching supply via an ancillary supply output signal.

9. The envelope tracking power supply of claim 1 wherein the switching circuitry is further configured to provide a switching current indicator signal to the parallel switching supply, such that the switching current indicator signal is representative of the current in the first inductive element and the estimate of the current in the first inductive element is based on the switching current indicator signal.

10. The envelope tracking power supply of claim 1 wherein the parallel switching supply comprises low bandwidth estimation circuitry configured to provide an estimated inductance signal, which is representative of an estimated inductance of the first inductive element, such that the estimate of the current in the first inductive element is based on the estimated inductance signal.

11. The envelope tracking power supply of claim 1 wherein the parallel switching supply comprises low bandwidth estimation circuitry configured to provide an estimated load resistance signal, which is representative of an estimated load resistance of the load, such that the estimate of the current in the load is based on the estimated load resistance signal.

12. The envelope tracking power supply of claim 1 wherein:
the parallel switching supply comprises low bandwidth estimation circuitry configured to provide an estimated offset voltage signal, which is representative of an offset capacitive voltage across the offset capacitive element; and
the assist current is further based on the estimated offset voltage signal.

13. The envelope tracking power supply of claim 1 wherein:
the parallel switching supply further comprises low bandwidth estimation circuitry and high bandwidth estimation circuitry;
the low bandwidth estimation circuitry is configured to provide a plurality of low bandwidth estimated signals to the high bandwidth estimation circuitry;
the high bandwidth estimation circuitry is configured to provide an assist current setpoint signal based on the plurality of low bandwidth estimated signals, the estimate of the current in the first inductive element, and the estimate of the current in the load;
a bandwidth of the assist current setpoint signal is at least two times a bandwidth of each of the plurality of low bandwidth estimated signals; and
the assist current is further based on the assist current setpoint signal.

14. The envelope tracking power supply of claim 1 wherein:
the parallel switching supply further comprises high bandwidth estimation circuitry;
the high bandwidth estimation circuitry is configured to receive the envelope power supply signal and the setpoint of the envelope power supply voltage;
the high bandwidth estimation circuitry is further configured to provide an assist current setpoint signal based on the envelope power supply voltage, the setpoint of the envelope power supply voltage, the estimate of the current in the first inductive element, and the estimate of the current in the load; and
the assist current is further based on the assist current setpoint signal.

15. The envelope tracking power supply of claim 1 wherein:
the parallel switching supply further comprises high bandwidth estimation circuitry;
the high bandwidth estimation circuitry is configured to receive a switching current indicator signal;
the high bandwidth estimation circuitry is further configured to provide an assist current setpoint signal based on the switching current indicator signal, the estimate of the current in the first inductive element, and the estimate of the current in the load; and
the assist current is further based on the assist current setpoint signal.

16. The envelope tracking power supply of claim 1 wherein:
the parallel switching supply further comprises high bandwidth estimation circuitry;
the high bandwidth estimation circuitry is configured to receive a switching output indicator signal;
the high bandwidth estimation circuitry is further configured to provide an assist current setpoint signal based on the switching output indicator signal, the estimate of the current in the first inductive element, and the estimate of the current in the load; and
the assist current is further based on the assist current setpoint signal.

17. The envelope tracking power supply of claim 1 wherein:
the parallel switching supply comprises assist switching circuitry;
the parallel switching supply further comprises a first assist inductive element coupled between the assist switching circuitry and the parallel switching supply output; and
the first assist inductive element has a first assist inductive element current, which is the assist current.

Assignees

• Qorvo Us Inc

Inventors

• Khlat Nadim
• Scott Baker
• Kay Michael R

Classifications

• H03F3/245

  with semiconductor devices only · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03F2200/375

  Circuitry to compensate the offset being present in an amplifier · CPC title

• H03F1/0244 Primary

  Stepped control · CPC title

• H03F2200/102

  A non-specified detector of a signal envelope being used in an amplifying circuit · CPC title