Power amplifiers with signal conditioning

Patent metadata

Field	Value
Publication number	US-9748903-B2
Application number	US-201514821517-A
Country	US
Kind code	B2
Filing date	Aug 7, 2015
Priority date	Oct 3, 2013
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

A device includes an amplifier having a first path and a second path and a first variable attenuator connected to the first path. The device includes a controller coupled to the first variable attenuator. The controller is configured to determine a magnitude of an input signal to the amplifier. When the magnitude of the input signal is below a threshold, the controller is configured to set an attenuation of the first variable attenuator to a first attenuation value. When the magnitude of the input signal is above the threshold, the controller is configured to set the attenuation of the first variable attenuator to a second attenuation value. The second attenuation value is less than the first attenuation value.

First claim

What is claimed is:

1. A device, comprising:
a first amplifier connected to a first path;
a second amplifier connected to a second path;
a variable attenuator connected to the second path;
an adjustable phase shifter connected to the second path; and
a controller configured to:
determine whether the first amplifier is at saturation,
when the first amplifier is not at saturation:
set an attenuation of the variable attenuator to a first attenuation value to force the second amplifier into a non-conducting condition, and
set a phase shift of the adjustable phase shifter to a first phase shift value, and

when the first amplifier is at saturation, set the phase shift of the adjustable phase shifter to a second phase shift value, the second phase shift value being greater than the first phase shift value.

2. The device of claim 1 , wherein the first attenuation value is a maximum attenuation of the variable attenuator.

3. The device of claim 1 , wherein the controller is configured to, when the first amplifier is at saturation, set the attenuation of the variable attenuator to a second attenuation value to allow the second amplifier to enter a conducting condition.

4. The device of claim 3 , wherein the second attenuation value is a minimum attenuation of the variable attenuator.

5. The device of claim 1 , wherein the controller is configured to set a gate bias of the second amplifier connected to the second path of the device.

6. The device of claim 5 , wherein the controller is configured to:
when the first amplifier is not at saturation, set the gate bias to a first gate bias voltage; and
when the first amplifier is at saturation, set the gate bias to a second gate bias voltage, the second gate bias voltage being greater than the first gate bias voltage.

7. The device of claim 1 , including:
a third amplifier connected to a third path; and
a second variable attenuator connected to the third path,
wherein the controller is configured to, when the second amplifier is not at saturation, set an attenuation of the second variable attenuator to force the third amplifier into a non-conducting condition.

8. The device of claim 1 , wherein the device is a Doherty amplifier and the first path is a carrier path and the first amplifier is a carrier amplifier and the second path is a peaking path and the second amplifier is a peaking amplifier.

9. A device, comprising:
an amplifier having a peaking path and a carrier path, the amplifier including a carrier amplifier configured to amplify a signal received from the carrier path and a peaking amplifier configured to amplify a signal received from the peaking path;
a first variable attenuator connected to the peaking path, the first variable attenuator configured to attenuate a signal to be input into the peaking amplifier;
a first adjustable phase shifter connected to the peaking path; and
a controller coupled to the first variable attenuator and the first adjustable phase shifter, the controller being configured to:
determine a magnitude of an input signal to the amplifier,
when the magnitude of the input signal is below a threshold:
set an attenuation of the first variable attenuator to a first attenuation value, and
set a phase shift of the first adjustable phase shifter to a first phase shift value,

detect that the magnitude of the input signal has transitioned to a value greater than the threshold, and
upon detecting that the magnitude of the input signal has transitioned to a value greater than the threshold:
transition the attenuation of the first variable attenuator to a second attenuation value through a non-zero number of attenuation values that fall between the first attenuation value and the second attenuation value, the second attenuation value being less than the first attenuation value, and
set the phase shift of the first adjustable phase shifter to a second phase shift value, the second phase shift value being greater than the first phase shift value.

10. The device of claim 9 , further comprising a second variable attenuator connected to the carrier path, the second variable attenuator configured to attenuate a signal to be input into the carrier amplifier, wherein the controller is configured to:
when the magnitude of the input signal is below the threshold, set an attenuation of the second variable attenuator to a third attenuation value, and
when the magnitude of the input signal is above the threshold, set the attenuation of the second variable attenuator to a fourth attenuation value, the third attenuation value being different from the fourth attenuation value.

11. The device of claim 10 , further comprising a second adjustable phase shifter connected to the carrier path, wherein the controller is configured to:
when the magnitude of the input signal is below the threshold, set a phase shift of the second adjustable phase shifter to a third phase shift value; and
when the magnitude of the input signal is above the threshold, set the phase shift of the second adjustable phase shifter to a fourth phase shift value, the fourth phase shift value being greater than the third phase shift value.

12. The device of claim 9 , wherein the amplifier is a Doherty amplifier.

13. The device of claim 12 , wherein the controller is configured to set a gate bias of the peaking amplifier connected to the peaking path of the Doherty amplifier.

14. The device of claim 13 , wherein the controller is configured to:
when the magnitude of the input signal is below the threshold, set the gate bias to a first gate bias voltage; and
when the magnitude of the input signal is above the threshold, set the gate bias to a second gate bias voltage, the second gate bias voltage being greater than the first gate bias voltage.

15. The device of claim 9 , further comprising:
a power splitter coupled to the carrier path and the peaking path.

16. A method, comprising:
determining a magnitude of an input signal to an amplifier, the amplifier including:
a carrier path,
a carrier amplifier configured to amplify a signal received from the carrier path,
a peaking path,
a peaking amplifier configured to amplify a signal received from the peaking path,
a first variable attenuator connected to the peaking path of the amplifier, the first variable attenuator configured to attenuate a signal to be input into the peaking amplifier, and
a first adjustable phase shifter connected to the peaking path;

when the magnitude of the input signal is below a threshold:
setting an attenuation of the first variable attenuator to a first attenuation value, and
setting a phase shift of the first adjustable phase shifter to a first phase shift value;

detecting that the magnitude of the input signal has transitioned to a value greater than the threshold; and
upon detecting that the magnitude of the input signal has transitioned to a value greater than the threshold:
transitioning the attenuation of the first variable attenuator to a second attenuation value through a non-zero number of attenuation values that fall between the first attenuation value and the second attenuation value, the second attenuation value being less than the first attenuation value, and
setting the phase shift of the first adjustable phase shifter to a second phase shift value, the second phase shift value being greater than the first phase shift value.

17. The method of claim 16 , wherein the amplifier further includes a second variable attenuator connected to the carrier path, the second variable attenuator configured to attenuate a

Assignees

• Staudinger Joseph
• Embar Ramanujam Srinidhi
• Nxp Usa Inc

Inventors

• Staudinger Joseph
• Embar Ramanujam Srinidhi

Classifications

• H03F3/19

  with semiconductor devices only · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03G3/3036

  in high-frequency amplifiers or in frequency-changers (H03G3/3052, H03G3/32, H03G3/34 take precedence) · CPC title

• H03F1/0288 Primary

  using a main and one or several auxiliary peaking amplifiers whereby the load is connected to the main amplifier using an impedance inverter, e.g. Doherty amplifiers · CPC title

• H03F3/211

  using a combination of several amplifiers (H03F3/60 takes precedence) · CPC title