Apparatus and methods for envelope tracking systems

Patent metadata

Field	Value
Publication number	US-10080192-B2
Application number	US-201715493580-A
Country	US
Kind code	B2
Filing date	Apr 21, 2017
Priority date	Feb 9, 2012
Publication date	Sep 18, 2018
Grant date	Sep 18, 2018

Abstract

Apparatus and methods for envelope tracking systems are disclosed herein. In certain implementations, an envelope tracking system for generating a power amplifier supply voltage for a power amplifier is provided. The envelope tracking system includes a DC-to-DC converter that generates a regulated voltage from a battery voltage and controls a voltage of the regulated voltage using a low frequency feedback signal. The envelope tracking system further includes an error amplifier that generates an output current using an envelope signal and a high frequency feedback signal. The low frequency feedback signal is based on a low frequency component of the power amplifier supply voltage and the high frequency feedback signal is based on a high frequency component of the power amplifier supply voltage. The error amplifier generates the power amplifier supply voltage by adjusting the magnitude of the regulated voltage using the output current.

First claim

What is claimed is:

1. A mobile device comprising:
a power amplifier configured to amplify a radio frequency signal and to receive power from a power amplifier supply voltage;
a DC-to-DC converter configured to generate a regulated voltage;
a high pass filter configured to generate a high pass filtered supply voltage based on high pass filtering the power amplifier supply voltage;
a first comparator configured to generate a high frequency envelope signal based on comparing the high pass filtered supply voltage to an envelope signal that changes in relation to an envelope of the radio frequency signal; and
an error amplifier configured to generate the power amplifier supply voltage by adjusting a voltage level of the regulated voltage based on the high frequency envelope signal.

2. The mobile device of claim 1 wherein the DC-to-DC converter is configured to generate the regulated voltage based on a control voltage.

3. The mobile device of claim 2 further comprising a low pass filter configured to generate a low pass filtered supply voltage based on low pass filtering the power amplifier supply voltage, and a second comparator configured to control a voltage level of the control voltage based on comparing the low pass filtered supply voltage to a reference voltage.

4. The mobile device of claim 3 further comprising a reference voltage generator configured to control a voltage level of the reference voltage based on digital data received over a serial interface.

5. The mobile device of claim 1 further comprising an AC coupling capacitor connected between an output of the error amplifier and the power amplifier supply voltage.

6. The mobile device of claim 5 further comprising a feedback circuit connected to the output of the error amplifier and configured to generate a feedback signal, the error amplifier including a first input configured to receive the high frequency envelope signal and a second input configured to receive the feedback signal.

7. The mobile device of claim 1 further comprising an inductor connected between the regulated voltage and the power amplifier supply voltage.

8. The mobile device of claim 1 further comprising a transceiver configured to generate the radio frequency signal and the envelope signal.

9. The mobile device of claim 1 further comprising a battery configured to provide a battery voltage to the DC-to-DC converter and to the error amplifier.

10. A radio frequency system comprising:
a power management integrated circuit including a DC-to-DC converter configured to generate a regulated voltage; and
a power amplifier module including a power amplifier configured to amplify a radio frequency signal and to receive power from a power amplifier supply voltage, a high pass filter configured to generate a high pass filtered supply voltage based on high pass filtering the power amplifier supply voltage, a first comparator configured to generate a high frequency envelope signal based on comparing the high pass filtered supply voltage to an envelope signal that changes in relation to an envelope of the radio frequency signal, and an error amplifier configured to generate the power amplifier supply voltage by adjusting a voltage level of the regulated voltage based on the high frequency envelope signal.

11. The radio frequency system of claim 10 wherein the DC-to-DC converter is configured to generate the regulated voltage based on a control voltage.

12. The radio frequency system of claim 11 wherein the power amplifier module further includes a low pass filter configured to generate a low pass filtered supply voltage based on low pass filtering the power amplifier supply voltage, and a second comparator configured to control a voltage level of the control voltage based on comparing the low pass filtered supply voltage to a reference voltage.

13. The radio frequency system of claim 12 wherein the power amplifier module further includes a serial interface configured to receive digital data and a reference voltage generator configured to control a voltage level of the reference voltage based on the digital data.

14. The radio frequency system of claim 10 wherein the power amplifier module further includes an AC coupling capacitor connected between an output of the error amplifier and the power amplifier supply voltage.

15. The radio frequency system of claim 14 wherein the power amplifier module further includes a feedback circuit connected to the output of the error amplifier and configured to generate a feedback signal, the error amplifier including a first input configured to receive the high frequency envelope signal and a second input configured to receive the feedback signal.

16. The radio frequency system of claim 10 wherein the power amplifier module further includes an inductor connected between the regulated voltage and the power amplifier supply voltage.

17. A method of envelope tracking in a power amplifier system, the method comprising:
providing a power amplifier supply voltage to a power amplifier;
amplifying a radio frequency signal using the power amplifier;
generating a regulated voltage using a DC-to-DC converter;
high pass filtering the power amplifier supply voltage to generate a high pass filtered supply voltage;
generating a high pass envelope signal based on comparing the high pass filtered supply voltage to an envelope signal that changes in relation to an envelope of the radio frequency signal; and
generating the power amplifier supply voltage by adjusting a voltage level of the regulated voltage based on the high frequency envelope signal using an error amplifier.

18. The method of claim 17 further comprising providing a control voltage to the DC-to-DC converter, and generating the regulated voltage based on the control voltage.

19. The method of claim 18 further comprising generating a low pass filtered supply voltage based on low pass filtering the power amplifier supply voltage, and controlling a voltage level of the control voltage based on comparing the low pass filtered supply voltage to a reference voltage.

20. The method of claim 19 further comprising receiving digital data over a serial interface, and controlling a voltage level of the reference voltage based on the digital data.

Assignees

• Skyworks Solutions Inc

Inventors

• Balteanu Florinel G
• Ripley David Steven
• Khesbak Sabah
• Strahler Jeffrey Gordon
• Arkiszewski Roman Zbigniew
• Tkachenko Yevgeniy A

Classifications

• H03F1/0222

  by using a signal derived from the input signal · CPC title

• H03F2200/336

  A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit · CPC title

• Y02D70/26

  Cross-Sectional Technologies · mapped topic

• H03F3/193

  with field-effect devices (H03F3/195 takes precedence) · CPC title

• H03F1/56

  Modifications of input or output impedances, not otherwise provided for · CPC title