PROGRAMMABLE LOW DROPOUT REGULATORS WITH FAST TRANSIENT RESPONSE WHEN PROGRAMMING OUTPUT VOLTAGE

• US 20190243403A1
• Filed: 04/19/2019
• Published: 08/08/2019
• Est. Priority Date: 08/17/2015
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Gebeyehu, Netsanet, Shi, Ying, Feng, Jinghang
• Granted Patent: US 10,642,296 B2
• Time in Patent Office: Days
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit
• CPC Class Codes: H03F 1/0227 using supply converters
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit
• CPC Class Codes: H03F 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit
• CPC Class Codes: H03F 2200/411 the output amplifying stage of an amplifier comprising two power stages
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/245 with semiconductor devices only

Abstract

Apparatus and methods for programmable low dropout regulators for radio frequency (RF) electronics are provided herein. In certain configurations, a power amplifier system includes a multi-stage power amplifier that amplifies a radio frequency signal and includes a driver stage and an output stage. The power amplifier system further includes an envelope tracker that controls a supply voltage of the output stage in relation to an envelope of the radio frequency signal, and a programmable low dropout regulator that includes an output that provides a programmable supply voltage to the driver stage. The programmable low dropout regulator includes an output capacitor electrically connected to the output, a regulation transistor having a drain electrically connected to the output, and an alternative discharge circuit that discharges the output capacitor in response to programming the programmable supply voltage from a high voltage level to a low voltage level.

Claims

1. A mobile device comprising:

a transceiver configured to generate a radio frequency signal;

a multi-stage power amplifier configured to amplify the radio frequency signal, the multi-stage power amplifier including a driver stage and an output stage; and

a power management system including an envelope tracker configured to control a supply voltage of the output stage in relation to an envelope of the radio frequency signal, and a programmable low dropout regulator including an output configured to provide a programmable supply voltage to the driver stage, the programmable low dropout regulator including an output capacitor electrically connected to the output, a regulation transistor having a drain electrically connected to the output, and an alternative discharge circuit configured to discharge the output capacitor in response to programming the programmable supply voltage from a high voltage level to a low voltage level.

2. The mobile device of claim 1 wherein the regulation transistor is configured to charge the output capacitor in response to programming the programmable supply voltage from the low voltage level to the high voltage level.

3. The mobile device of claim 2 wherein the alternative discharge circuit is electrically connected between the output of the programmable low dropout regulator and a ground voltage.

4. The mobile device of claim 2 wherein the alternative discharge circuit includes a comparator configured to compare the programmable supply voltage to a trigger voltage, and to selectively activate an electrical path through the alternative discharge circuit based on the comparison.

5. The mobile device of claim 4 wherein the alternative discharge circuit further includes a discharge transistor in the electrical path and including a gate controlled by an output of the comparator.

6. The mobile device of claim 4 wherein the programmable low dropout regulator is configured to receive a control signal operable to control a programmed voltage level of the programmable supply voltage, the alternative discharge circuit configured to adjust a voltage level of the trigger voltage based on the control signal.

7. The mobile device of claim 1 wherein the programmable low dropout regulator further includes an error amplifier configured to control a gate of the regulation transistor.

8. The mobile device of claim 1 further comprising an antenna configured to transmit an amplified radio frequency signal from the multi-stage power amplifier.

9. A power amplifier system comprising:

a multi-stage power amplifier configured to amplify a radio frequency signal, the multi-stage power amplifier including a driver stage and an output stage;

an envelope tracker configured to control a supply voltage of the output stage in relation to an envelope of the radio frequency signal; and

a programmable low dropout regulator including an output configured to provide a programmable supply voltage to the driver stage, the programmable low dropout regulator including an output capacitor electrically connected to the output, a regulation transistor having a drain electrically connected to the output, and an alternative discharge circuit configured to discharge the output capacitor in response to programming the programmable supply voltage from a high voltage level to a low voltage level.

10. The power amplifier system of claim 9 wherein the regulation transistor is configured to charge the output capacitor in response to programming the programmable supply voltage from the low voltage level to the high voltage level.

11. The power amplifier system of claim 9 wherein the alternative discharge circuit is electrically connected between the output of the programmable low dropout regulator and a ground voltage.

12. The power amplifier system of claim 9 wherein the alternative discharge circuit includes a comparator configured to compare the programmable supply voltage to a trigger voltage, and to selectively activate an electrical path through the alternative discharge circuit based on the comparison.

13. The power amplifier system of claim 12 wherein the alternative discharge circuit further includes a discharge transistor in the electrical path and including a gate controlled by an output of the comparator.

14. The power amplifier system of claim 12 wherein the programmable low dropout regulator is configured to receive a control signal operable to control a programmed voltage level of the programmable supply voltage, the alternative discharge circuit configured to adjust a voltage level of the trigger voltage based on the control signal.

15. The power amplifier system of claim 9 wherein the programmable low dropout regulator further includes an error amplifier configured to control a gate of the regulation transistor.

16. A method of signal amplification in a mobile device, the method comprising:

amplifying a radio frequency signal using a driver stage and an output stage of a multi-stage power amplifier;

controlling a supply voltage of the output stage in relation to an envelope of the radio frequency signal using an envelope tracker; and

providing the driver stage with a programmable supply voltage from an output of a programmable low dropout regulator, including stabilizing the programmable supply voltage using an output capacitor electrically connected to the output, regulating the programmable supply voltage using a regulation transistor having a drain electrically connected to the output, and discharging the output capacitor using an alternative discharge circuit in response to programming the programmable supply voltage from a high voltage level to a low voltage level.

17. The method of claim 16 further comprising charging the output capacitor using the regulation transistor in response to programming the output voltage from the low voltage level to the high voltage level.

18. The method of claim 16 further comprising comparing the programmable supply voltage to a trigger voltage, and selectively activating an electrical path through the alternative discharge circuit based on the comparison.

19. The method of claim 18 further comprising programming the voltage level of the programmable supply voltage using a control signal, and adjusting a voltage level of the trigger voltage based on the control signal.

20. The method of claim 18 wherein selectively activating the electrical path through the alternative discharge circuit includes controlling a gate of a discharge transistor based on the comparison, and limiting an amount of current through the alternative discharge circuit using a discharge control circuit that is in series with the discharge transistor.