Radio frequency amplifiers with an injection-locked oscillator driver stage and a stacked output stage

• US 10,454,432 B2
• Filed: 12/27/2017
• Issued: 10/22/2019
• Est. Priority Date: 12/29/2016
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Soliman, Yasser Khairat
• Primary Examiner(s): Nguyen, Khanh V
• Assistant Examiner(s): Nguyen, Khiem D
• Application Number:
  US15/855,065
• Publication Number:
  US 20180219516A1
• Time in Patent Office: 664 Days
• Field of Search: 330277, 330311, 330133, 330302
• CPC Class Codes: H03B 2200/0074 Locking of an oscillator by injecting an input signal directly into the oscillator
• CPC Class Codes: H03F 1/223 with MOSFET's
• 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 2200/516 Some amplifier stages of an amplifier use supply voltages of different value
• CPC Class Codes: H03F 2200/61 the cascode amplifier has more than one common gate stage
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/195 in integrated circuits
• CPC Class Codes: H03L 7/083 the reference signal being additionally directly applied to the generator
• CPC Class Codes: H03L 7/24 using a reference signal directly applied to the generator

Abstract

Radio frequency (RF) amplifiers, such as power amplifiers, are provided herein. In certain configurations, an RF amplifier includes an input terminal that receives an RF input signal, an output terminal that provides an RF output signal, an injection-locked oscillator driver stage that amplifies the RF input signal to generate an injection-locked RF signal, and a stacked output stage that further amplifies the injection-locked RF signal to generate the RF output signal. The stacked output stage includes a stack of at least a first transistor and a second transistor in series with one another. Thus, the stacked output stage is operable over a wide range of supply voltage to overcome the relatively low breakdown voltages of scaled transistors. Moreover, the injection-locked oscillator driver stage provides the RF amplifier with excellent power efficiency, including in applications in which the stacked output stage operates with a supply voltage that is variable.

Claims

1. A radio frequency amplifier comprising:

an input terminal configured to receive a radio frequency input signal;

an output terminal configured to provide a radio frequency output signal;

a driver stage including an injection-locked oscillator configured to generate an injection-locked radio frequency signal based on the radio frequency input signal; and

a stacked output stage configured to amplify the injection-locked radio frequency signal to generate the radio frequency output signal, the stacked output stage including a transistor stack of at least a first transistor and a second transistor in series with one another, the stacked output stage having an adjustable supply voltage that changes with a mode of the radio frequency amplifier.

2. The radio frequency amplifier of claim 1 wherein the stacked output stage is operable in at least a first mode and a second mode.

3. The radio frequency amplifier of claim 2 further comprising a bias circuit configured to bias the second transistor to a linear region of operation in the first mode, and to bias the second transistor as a switch in the second mode.

4. The radio frequency amplifier of claim 2 wherein the stacked output stage is configured to receive a supply voltage having a lower voltage level in the second mode relative to the first mode.

5. The radio frequency amplifier of claim 2 further comprising a switch configured to provide the injection-locked radio frequency signal to the second transistor in the first mode, and to provide the injection-locked radio frequency signal to the first transistor in the second mode.

6. The radio frequency amplifier of claim 1 wherein the first transistor is a common source transistor, and the second transistor is a common gate transistor.

7. The radio frequency amplifier of claim 1 wherein the driver stage is a power amplifier input stage, and the stacked output stage is a power amplifier output stage.

8. The radio frequency amplifier of claim 1 wherein the driver stage is powered by a substantially fixed supply voltage.

9. The radio frequency amplifier of claim 1 wherein the radio frequency input signal is a single-ended input signal, and the injection-locked oscillator includes an input transformer configured to convert the single-ended input signal to a differential input signal.

10. The radio frequency amplifier of claim 1 wherein the injection-locked oscillator includes a negative transconductance circuit electrically connected to an inductor-capacitor tank, the negative transconductance circuit configured to provide energy to the inductor-capacitor tank to maintain oscillations.

11. The radio frequency amplifier of claim 10 wherein the injection-locked oscillator further includes a signal injecting circuit configured to provide signal injection to the inductor-capacitor tank based on the radio frequency input signal.

12. The radio frequency amplifier of claim 10 wherein the injection-locked oscillator further includes an output transformer configured to generate the injection-locked radio frequency signal at the output of the driver stage.

13. A method of radio frequency signal amplification, the method comprising:

receiving a radio frequency input signal as an input to a radio frequency amplifier having a driver stage and a stacked output stage;

generating an injection-locked radio frequency signal based on the radio frequency input signal using an injection-locked oscillator of the driver stage;

amplifying the injection-locked radio frequency signal using a transistor stack of the stacked output stage, the transistor stack including at least a first transistor and a second transistor in series with one another;

operating the stacked output stage in a selected mode chosen from at least a first mode and a second mode; and

providing the stacked output stage with an adjustable supply voltage having a lower voltage level in the second mode relative to the first mode.

14. The method of claim 13 further comprising biasing the second transistor to a linear region of operation in the first mode, and biasing the second transistor as a switch in the second mode.

15. A wireless communication device comprising:

a transmitter configured to generate a radio frequency input signal;

a power amplifier including a driver stage and a stacked output stage, the driver stage including an injection-locked oscillator configured to generate an injection-locked radio frequency signal based on the radio frequency input signal, and the stacked output stage configured to amplify the injection-locked radio frequency signal to generate an output radio frequency signal, the stacked output stage including a transistor stack of at least a first transistor and a second transistor in series with one another and powered by a second supply voltage; and

a supply control circuit configured to generate the second supply voltage, the supply control circuit configured to receive a mode control signal from the transmitter.

16. The wireless communication device of claim 15 further comprising a switch and an antenna electrically connected to an output of the stacked output stage via the switch.

17. The wireless communication device of claim 15 further comprising a bias circuit configured to bias the second transistor to a linear region of operation in a first mode, and to bias the second transistor as a switch in a second mode.

18. The wireless communication device of claim 17 wherein the supply control circuit is further configured to control the second supply voltage to a lower voltage level in the second mode relative to the first mode.

19. The wireless communication device of claim 15 wherein the power amplifier further includes a switch configured to provide the injection-locked radio frequency signal to the second transistor in the first mode, and to provide the injection-locked radio frequency signal to the first transistor in the second mode.

20. The wireless communication device of claim 15 wherein the injection-locked oscillator includes a negative transconductance circuit electrically connected to an inductor-capacitor tank, the negative transconductance circuit configured to provide energy to the inductor-capacitor tank to maintain oscillations.