Envelope tracking path delay fine tuning and calibration

Patent metadata

Field	Value
Publication number	US-9692366-B2
Application number	US-201414564162-A
Country	US
Kind code	B2
Filing date	Dec 9, 2014
Priority date	Dec 9, 2014
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A power amplifier of an envelope tracking system is configured to generate an output power with a variable supply voltage that is generated in an envelope tracking path. A signal generation/processing path receives an input signal and processes the input signal to the power amplifier in a main signal processing path. A delay component is configured to generate a delay to the envelope tracking path with respect to the signal generation path. A feedback path is configured to generate a feedback signal from the output of the power amplifier and adjust the delay component or the delay of the delay component during an active transmission or an active transmission mode.

First claim

What is claimed is:

1. An envelope tracking system, comprising:
a transmitter configured to generate an output signal;
an envelope tracking path configured to adaptively generate a supply voltage that varies based on an instantaneous envelope signal derived from an input signal;
a signal processing path configured to generate a converted signal via a signal conversion of the input signal and provide the converted signal to a power amplifier;
a delay component configured to generate a first delay of the envelope tracking path with respect to a second delay of the signal processing path, the first delay being tunable and based on a feedback signal of a feedback path that is derived from the output signal;
a calibration component, operatively coupled to a cross-correlation component and the signal processing path downstream of the envelope tracking path branching from the signal processing path, configured to generate an in-band calibration signal based on the input signal and provide the in-band calibration signal to the cross-correlation component and to the signal processing path at a point downstream after the envelope tracking path branches from the signal processing path to isolate the in-band calibration signal from being received in the envelope tracking path; and
the cross-correlation component, operatively coupled to a calibration path from the calibration component and the feedback path, configured to receive the in-band calibration signal from the calibration component separate from the input signal that is at the signal processing path and concurrent with the signal processing path processing the input signal, and perform a cross-correlation function of the in-band calibration signal received from the calibration path and the feedback signal received from the feedback path by identifying similar portions of the in-band calibration signal and the feedback signal.

2. The envelope tracking system of claim 1 , wherein the delay component is further configured to modify the first delay of the envelope tracking path based on the feedback signal and the in-band calibration signal received during an active transmission of the transmitter, and wherein the cross-correlation component is further configured to preserve a spectral mask of the input signal by preventing an interference from being added to the input signal at the signal processing path by receiving the in-band calibration signal independently of and separately from the input signal and concurrent to the signal processing path processing the input signal with the in-band calibration downstream after branching from the envelope tracking path.

3. The envelope tracking system of claim 1 , further comprising:
a feedback receiver, located in the feedback path, configured to generate the feedback signal derived from the output signal during an active transmission of the transmitter.

4. The envelope tracking system of claim 1 , further comprising:
a feedback receiver, located in the feedback path, configured to generate the feedback signal derived from the output signal at the first delay during an active transmission of the transmitter, and a second feedback signal derived from the output signal that is at a higher or a lower delay than the first delay during the active transmission of the transmitter.

5. The envelope tracking system of claim 1 , further comprising:
a root mean squared (RMS) component configured to generate a first root mean squared value of the cross-correlation function derived from the in-band calibration signal and the feedback signal of the feedback path.

6. The envelope tracking system of claim 5 , wherein the RMS component is further configured to generate a second root mean squared value based on a second feedback signal from the feedback path, wherein the second feedback signal is different from the feedback signal.

7. The envelope tracking system of claim 6 , further comprising:
an estimation component configured to generate a maximum root mean squared value based on a comparison of the second root mean squared value and the first root mean squared value and adjust the first delay based on the maximum root mean squared value.

8. The envelope tracking system of claim 1 , further comprising:
a delay correction component, located within the feedback path, configured to generate a correction value based on the feedback signal and the in-band calibration signal, and correct a deviation of an actual delay of the delay component from a target delay.

9. The envelope tracking system of claim 1 , further comprising:
an estimation component configured to generate a plurality of peak values associated with normalized values of the cross-correlation function, select at least one peak value of the plurality of peak values that satisfies a predetermined threshold, and providing the at least one peak value to the envelope tracking path to control the first delay.

10. A power amplifier device comprising:
a power amplifier, coupled to a signal generation path and an envelope tracking path, comprising a supply voltage input configured to receive a supply voltage that varies according to an input signal of a transmitter and an output configured to provide an output signal of the power amplifier;
a delay component configured to generate a first delay of the envelope tracking path to correspond with a second delay of the signal generation path;
a feedback path extending between the output of the power amplifier and a feedback input to the delay component, the feedback path comprising:
a feedback receiver, coupled to the output of the power amplifier, configured to generate a feedback signal based on the output signal;
a calibration component, operatively coupled to a cross-correlation component and a signal processing path downstream of where the envelope tracking path branches from the signal processing path, configured to generate a calibration signal based on the input signal and provide the calibration signal to the cross-correlation component and to the signal processing path at a point downstream after the envelope tracking path branches from the signal processing path to isolate the calibration signal from being received in the envelope tracking path; and
a delay correction component, coupled to the feedback receiver and the delay component, configured provide a correction value that is based on the feedback signal, wherein the delay component is further configured to correct a deviation of the first delay of the envelope tracking path from a target delay based on the correction value, comprising:
the cross-correlation component, operatively coupled to a calibration path from the calibration component and the feedback receiver, configured to receive the calibration signal independently of, and separately from, the input signal that is at the signal processing path and concurrent with the signal processing path processing the input signal, perform a cross-correlation function of the calibration signal received from the calibration path and the feedback signal received from the feedback receiver by identifying similar portions of the calibration signal and the feedback signal.

11. The power amplifier device of claim 10 , wherein the delay correction component is configured to receive the calibration signal via a calibration input of the calibration path, generate the correction value as a function of the calibration signal and the feedback signal and provide the calibration signal to the signal generation path while not providing the calibration signal to the envelope tracking path.

12. The power amplifier device of claim 10 , wherein the calibration component is further configured to generate the

Assignees

• Intel Corp

Inventors

• Pilgram Berndt

Classifications

• H03F2200/336

  A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit · CPC title

• H04B2001/0408

  with power amplifiers · CPC title

• H03F2201/3233

  Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion · CPC title

• H03F1/305 Primary

  in case of switching on or off of a power supply · CPC title

• H03F3/19 Primary

  with semiconductor devices only · CPC title