Voltage offset loop for a switching controller

• US 9,256,234 B2
• Filed: 01/23/2013
• Issued: 02/09/2016
• Est. Priority Date: 12/01/2011
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Kay, Michael R., Khlat, Nadim
• Primary Examiner(s): Nguyen, Matthew
• Assistant Examiner(s): DANG, TRINH Q
• Application Number:
  US13/747,749
• Publication Number:
  US 20130141064A1
• Time in Patent Office: 1,112 Days
• Field of Search: 323/271, 323/282, 323/283, 323/284, 323/285, 323/272, 323/273, 323/274, 323/266, 361/18, 361/23, 361/90, 361/115, 361/689
• US Class Current: 1/1
• CPC Class Codes: G05F 1/46 wherein the variable actually regulated by the final control device is dc G05F1/625 takes precedence
• CPC Class Codes: H02M 1/0067 Converter structures employing plural converter units, other than for parallel operation of the units on a single load
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• CPC Class Codes: H03F 1/0227 using supply converters
• CPC Class Codes: H03F 1/26 Modifications of amplifiers to reduce influence of noise generated by amplifying elements
• CPC Class Codes: H03F 2200/351 Pulse width modulation being used in an amplifying circuit
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/504 the supply voltage or current being continuously controlled by a controlling signal, e.g. the controlling signal of a transistor implemented as variable resistor in a supply path for, an IC-block showed amplifier
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 15/005 Reducing noise, e.g. humm, from the supply

Abstract

This disclosure relates to radio frequency (RF) power converters and methods of operating the same. In one embodiment, an RF power converter includes an RF switching converter, a low-drop out (LDO) regulation circuit, and an RF filter. The RF filter is coupled to receive a pulsed output voltage from the RF switching converter and a supply voltage from the LDO regulation circuit. The RF filter is operable to alternate between a first RF filter topology and a second RF filter topology. In the first RF filter topology, the RF filter is configured to convert the pulsed output voltage from a switching circuit into the supply voltage. The RF filter in the second RF filter topology is configured to filter the supply voltage from the LDO regulation circuit to reduce a ripple variation in a supply voltage level of the supply voltage. As such, the RF filter provides greater versatility.

Claims

1. A radio frequency (RF) switching converter comprising:

a switching circuit operable to receive a power source voltage, the switching circuit being switchable so as to generate a pulsed output voltage from the power source voltage;

an RF filter configured to convert the pulsed output voltage into a supply voltage having a supply voltage level with a ripple variation and operable to bias the supply voltage with a supply control output voltage having a supply control output voltage level such that the supply voltage level and the supply control output voltage level are displaced by a displacement voltage magnitude; and

a voltage offset loop (VOL) configured to generate an offset voltage having an offset voltage magnitude in a first operational mode and to generate an Average Power Tracking (APT) signal having an APT signal level that varies from a DC offset signal level in accordance with the ripple variation of the supply voltage level of the supply voltage in a second operational mode;

a bang-bang controller (BBC) configured to switch the switching circuit so that the switching circuit generates the pulsed output voltage, wherein when the VOL is in the first operational mode, the displacement voltage magnitude is set by the offset voltage magnitude of the offset voltage, and when the VOL is in the second operational mode, the supply voltage level of the supply voltage has an average DC supply voltage level set in accordance with the DC offset signal level of the APT signal.

2. The RF switching converter of claim 1 wherein the supply voltage level of the supply voltage has the ripple variation and wherein:

the RF filter comprises a power inductor coupled in series with the switching circuit to produce a power inductor current in response to the pulsed output voltage such that a power inductor current level of the power inductor current varies in accordance with the ripple variation of the supply voltage level;

a switching controller is operable in the first operational mode and in the second operational mode wherein the switching controller includes the BBC and the VOL, and wherein the switching controller is configured to;

generate the supply control output voltage in the first operational mode; and

generate a current sense signal having a sense signal level that is indicative of the power inductor current in the first operational mode; and

the BBC is operable to receive the offset voltage from the VOL and the current sense signal when the VOL is in the first operational mode, and to receive the APT signal from the VOL when the VOL is in the second operational mode, the BBC being configured to;

switch the switching circuit based on the sense signal level of the current sense signal so that the switching circuit generates the pulsed output voltage and such that the displacement voltage magnitude is set by the offset voltage magnitude of the offset voltage in the first operational mode; and

switch the switching circuit based on the APT signal level of the APT signal so that the switching circuit generates the pulsed output voltage and so that the supply voltage level of the supply voltage has the average DC supply voltage level set in accordance with the DC offset signal level of the APT signal when the VOL is in the second operational mode.

3. The RF switching converter of claim 1 wherein the supply voltage level of the supply voltage has the ripple variation and wherein:

the RF filter comprises a power inductor coupled in series with the switching circuit to produce a power inductor current in response to the pulsed output voltage such that a power inductor current level of the power inductor current varies in accordance with the ripple variation of the supply voltage level;

a switching controller is operable in the first operational mode and in the second operational mode wherein the switching controller includes the BBC and the VOL, and wherein the switching controller is configured to;

generate the supply control output voltage in the first operational mode; and

generate a current sense signal having a sense signal level that is indicative of the power inductor current in the first operational mode; and

the BBC is configured to switch the switching circuit based on a sense voltage level of a sense voltage, and the BBC is further configured to;

generate the sense voltage from the current sense signal such that the sense voltage level is set in accordance with the sense signal level and is offset in accordance with the offset voltage magnitude of the offset voltage to set the displacement voltage magnitude when the offset voltage is received; and

generate the sense voltage from the APT signal when the APT signal is received such that the sense voltage level is set in accordance with the APT signal level.

4. The RF switching converter of claim 1 further comprising a linear amplification circuit wherein:

the linear amplification circuit is operable to be activated and deactivated; and

the linear amplification circuit is configured to generate the supply control output voltage when activated.

5. The RF switching converter of claim 1 wherein the VOL comprises an integrator circuit wherein the integrator circuit is configured to integrate an error voltage having an error voltage magnitude so as to generate the offset voltage in the first operational mode, and so as to generate the APT signal in the second operational mode.

6. The RF switching converter of claim 2 wherein the switching controller does not generate the supply control output voltage in the second operational mode.

7. The RF switching converter of claim 3 wherein the switching controller does not generate the supply control output voltage in the second operational mode.

8. The RF switching converter of claim 4 wherein:

the linear amplification circuit is operable to receive a supply control input signal having a supply control input signal level when the linear amplification circuit is activated, wherein the linear amplification circuit is configured to generate the supply control output voltage such that the supply control output voltage level of the supply control output voltage is set in accordance with the supply control input signal level when the linear amplification circuit is activated.

9. The RF switching converter of claim 5 wherein the VOL is configured to generate the error voltage such that:

the error voltage magnitude is indicative of a difference between the displacement voltage magnitude and a target displacement voltage magnitude in the first operational mode; and

the error voltage magnitude is indicative of a deviation of the supply voltage level from a target DC offset signal level in the second operational mode.

10. The RF switching converter of claim 8 wherein the VOL is operable to receive the supply control input signal when the linear amplification circuit is deactivated, and to set the DC offset signal level of the APT signal in accordance with the supply control input signal level of the supply control input signal in the second operational mode.

11. The RF switching converter of claim 8 wherein:

the RF filter comprises a power inductor coupled in series with the switching circuit to produce a power inductor current in response to the pulsed output voltage, such that a power inductor current level of the power inductor current varies in accordance with the ripple variation of the supply voltage level; and

a current sense detector is operable to be activated and deactivated, wherein the current sense detector includes the linear amplification circuit and is configured to generate a current sense signal having a sense signal level that is indicative of the power inductor current when activated.

12. The RF switching converter of claim 9 wherein the VOL further comprises a first adder, and a second adder to generate the error voltage, and wherein:

the APT signal is an APT voltage and the APT signal level is an APT voltage level;

the DC offset signal level is a DC offset signal voltage level;

the first adder is configured to;

receive a first feedback voltage having a first feedback voltage level that is indicative of the supply voltage level of the supply voltage;

output a displacement indication voltage having a displacement indication voltage magnitude;

receive a second feedback voltage having a second feedback voltage level that is indicative of the supply control output voltage level of the supply control output voltage in the first operational mode, wherein the displacement indication voltage magnitude is set in accordance with a difference between the first feedback voltage level and the second feedback voltage level;

receive a reference voltage having a reference voltage level in the second operational mode, wherein the displacement indication voltage magnitude is set in accordance with a difference between the first feedback voltage level and the reference voltage level; and

the second adder is configured to;

receive the displacement indication voltage from the first adder;

output the error voltage;

receive a target displacement voltage signal having a target displacement voltage level that is indicative of the target displacement voltage magnitude in the first operational mode so that the error voltage magnitude is indicative of a difference between the displacement voltage magnitude and the target displacement voltage magnitude; and

receive a supply control input voltage having a supply control input voltage level that is indicative of a target DC offset signal voltage level so that the error voltage magnitude is indicative of the deviation of the supply voltage level from the target DC offset signal voltage level in the second operational mode.

13. The RF switching converter of claim 10 wherein the supply control input signal is a supply control input voltage and the supply control input signal level is a supply control input voltage level.

14. The RF switching converter of claim 11 wherein the RF filter further comprises a decoupling capacitor that is configured to receive the supply voltage and is operable to bias the supply voltage with the supply control output voltage such that the displacement voltage magnitude is provided across the decoupling capacitor.

15. The RF switching converter of claim 14 wherein:

the linear amplification circuit is configured to generate a supply current that is injected into the decoupling capacitor, and such that a first change in the power inductor current level of the power inductor current results in a second change in a supply current level of the supply current, the second change being negatively proportional to the first change; and

the current sense detector being configured to generate the current sense signal in response to the supply current, such that the sense signal level is directly proportional to the supply current level of the supply current.

16. A radio frequency (RF) power converter comprising:

a switching circuit operable to receive a power source voltage, the switching circuit being switchable so as to generate a pulsed output voltage from the power source voltage;

an RF filter configured to convert the pulsed output voltage into a supply voltage having a supply voltage level with a ripple variation, and operable to bias the supply voltage with a supply control output voltage having a supply control voltage level such that the supply voltage level and the supply control output voltage level are displaced by a displacement voltage magnitude;

a voltage offset loop (VOL) configured to generate an offset voltage having an offset voltage magnitude in a first operational mode, and to generate an Average Power Tracking (APT) signal having an APT signal level that varies from a DC offset signal level in accordance with the ripple variation of the supply voltage level of the supply voltage in a second operational mode;

a bang-bang controller (BBC) configured to switch the switching circuit so that the switching circuit generates the pulsed output voltage, wherein when the VOL is in the first operational mode, the displacement voltage magnitude is set by the offset voltage magnitude of the offset voltage, and when the VOL is in the second operational mode, the supply voltage level of the supply voltage has an average DC supply voltage level set in accordance with the DC offset signal level of the APT signal; and

an operational mode controller configured to provide the VOL in the first operational mode and in the second operational mode.

17. The RF power converter of claim 16 wherein the operational mode controller is configured to obtain a target average power output parameter that identifies a target average power output value, the operational mode controller being configured to select between the first operational mode and the second operational mode based on the target average power output parameter.

18. The RF power converter of claim 17 wherein the operational mode controller is configured to select the first operational mode when the target average power output value identified by the target average power output parameter is above a threshold value.

19. The RF power converter of claim 17 wherein the operational mode controller is configured to select the second operational mode when the target average power output value identified by the target average power output parameter is below a threshold value.

20. The RF power converter of claim 17 wherein the operational mode controller is configured to:

select the first operational mode when the target average power output value identified by the target average power output parameter is above a first threshold value; and

select the second operational mode when the target average power output value identified by the target average power output parameter is below a second threshold value that is less than the first threshold value.