Pseudo-envelope following power management system

• US 9,621,113 B2
• Filed: 03/04/2015
• Issued: 04/11/2017
• Est. Priority Date: 04/19/2010
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Inventors: Khlat, Nadim, Kay, Michael R.
• Primary Examiner(s): Nguyen, Patricia T
• Application Number:
  US14/638,374
• Publication Number:
  US 20150180422A1
• Time in Patent Office: 769 Days
• Field of Search: 330291, 330297, 330127, 327536
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H03F 1/0238 using supply converters
• CPC Class Codes: H03F 1/0244 Stepped control
• CPC Class Codes: H03F 1/025 by using a signal derived from the input signal
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit
• CPC Class Codes: H03F 2200/375 Circuitry to compensate the offset being present in an amplifier
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/555 A voltage generating circuit being realised for biasing different circuit elements
• CPC Class Codes: H03F 3/189 High-frequency amplifiers, e.g. radio frequency amplifiers
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/21 with semiconductor devices only H03F3/245 takes precedence
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03G 3/004 Control by varying the supply voltage

Abstract

Embodiments disclosed in the detailed description relate to a pseudo-envelope follower power management system used to manage the power delivered to a linear RF power amplifier.

Claims

1. A power management system for an RF power amplifier comprising:

a parallel amplifier circuit comprising;

an amplifier in communication with a power amplifier supply voltage; and

a voltage offset loop circuit configured to provide a threshold offset current as a feedback signal; and

a multi-level charge pump buck converter comprising;

a switcher control circuit configured to receive the feedback signal from the voltage offset loop circuit and output a logic level indication; and

a frequency lock loop (FLL) in communication with the switcher control circuit and receiving the logic level indication.

2. The power management system of claim 1, further comprising a coupling circuit coupled to an output of the parallel amplifier circuit, and wherein the feedback signal estimates a magnitude of an offset voltage appearing across the coupling circuit.

3. The power management system of claim 1, wherein the voltage offset loop circuit comprises a first subtractor circuit, the first subtractor circuit comprising a voltage offset output, the first subtractor circuit configured to receive the power amplifier supply voltage and an output from the parallel amplifier circuit.

4. The power management system of claim 3, wherein the voltage offset loop circuit comprises a second subtractor circuit, the second subtractor circuit comprising an input coupled to the voltage offset output and an offset error output.

5. The power management system of claim 4, wherein the voltage offset loop circuit comprises an integrator coupled to the offset error output and wherein the integrator comprises a threshold offset current output.

6. The power management system of claim 1 wherein as the threshold offset current rises above zero current, an output frequency of the multi-level charge pump buck converter is lowered.

7. The power management system of claim 6, further comprising a power inductor coupled to an output of the multi-level charge pump buck converter, wherein as the output frequency decreases, current output from the power inductor decreases.

8. The power management system of claim 7, wherein as the current output from the power inductor decreases, an offset voltage within the voltage offset loop circuit decreases.

9. The power management system of claim 1 wherein as the threshold offset current sinks below zero current, an output frequency of the multi-level charge pump buck converter is increased.

10. The power management system of claim 9, further comprising a power inductor coupled to an output of the multi-level charge pump buck converter, wherein as the output frequency increases, current output from the power inductor increases.

11. The power management system of claim 10, wherein as the current output from the power inductor increases, an offset voltage within the voltage offset loop circuit increases.

12. A method of controlling a power management system for an RF power amplifier, comprising:

providing a threshold offset current as a feedback signal from a voltage offset loop circuit;

receiving the feedback signal at a switcher control circuit of a multi-level charge pump buck converter;

outputting a logic level indication from the switcher control circuit;

receiving the logic level indication at a frequency lock loop (FLL).

13. The method of claim 12 further comprising estimating, with the feedback signal, a magnitude of an offset voltage appearing across a coupling circuit.

14. The method of claim 12, further comprising generating a threshold offset current output with an integrator in the voltage offset loop circuit.

15. The method of claim 12, further comprising lowering an output frequency of the multi-level charge pump buck converter as the threshold offset current rises above zero current.

16. The method of claim 12, further comprising increasing an output frequency of the multi-level charge pump buck converter as the threshold offset current sinks below zero current.