Time alignment algorithm for transmitters with EER/ET amplifiers and others

• US 8,542,766 B2
• Filed: 04/29/2011
• Issued: 09/24/2013
• Est. Priority Date: 05/04/2010
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Haddad, Khalil, Chekhovstov, Igor
• Primary Examiner(s): Nguyen, Leon-Viet
• Assistant Examiner(s): Hassan, Sarah
• Application Number:
  US13/097,844
• Publication Number:
  US 20110274210A1
• Time in Patent Office: 879 Days
• Field of Search: 375/296, 704/223
• US Class Current: 375/296
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

An apparatus and method for aligning input and feedback signals in a transmission circuit are provided. The method includes capturing an input signal and a feedback signal, determining a first time delay between the input signal and the feedback signal, determining a second time delay between the input signal and the feedback signal, the determination of the second time delay having a higher resolution than the determination of the first time delay, and applying the first time delay and the second time delay to temporally align the input signal with the feedback signal. Use of the present invention provides an improved resolution of time alignment while reducing the overall complexity and cost of the transmission circuit.

Claims

1. A method for amplifying a transmission signal by a non-linear power amplifier, the method comprising:

capturing an input signal and a feedback signal;

determining a first time delay between the input signal and the feedback signal;

determining, by a first number of filters, a second time delay between the input signal and the feedback signal, the determination of the second time delay having a higher resolution than the determination of the first time delay;

determining a first Measure of Error (ME) for each of the first number of filters using one equation selected from among the following equations;

2. The method of claim 1, further comprising:

determining a minimum ME from among the determined first MEs; and

applying the first filter corresponding to the minimum first ME as the second time delay.

3. The method of claim 1, further comprising:

determining a third time delay between the input signal and the feedback signal;

determining a fourth time delay between the input signal and the feedback signal, the determination of the fourth time delay having a higher resolution than the determination of the third time delay; and

applying the third time delay and the fourth time delay to temporally align an envelope signal with a forward path signal.

4. The method of claim 3, further comprising determining a number of second filters with which to determine the fourth time delay.

5. The method of claim 4, further comprising:

determining a first ME for each of the second filters;

determining a minimum ME from among the determined second MEs; and

applying the second filter corresponding to the minimum second ME as the fourth time delay.

6. The method of claim 1, further comprising:

creating a Finite Impulse Response (FIR) filter;

sequentially loading the FIR filter with each of the first filters;

sequentially passing the captured feedback signal through the FIR filter loaded with the first filters to determine an output corresponding to each of the first filters;

determining a ME corresponding to each of the first filters using the output of the FIR filter and the input signal; and

determining a minimum ME from among the determined MEs.

7. An apparatus for amplifying a transmission signal, the apparatus comprising:

a controller for capturing an input signal and a feedback signal, for determining a first time delay between the input signal and the feedback signal, and for determining a second time delay between the input signal and the feedback signal, the determination of the second time delay having a higher resolution than the determination of the first time delay;

a first integer delay for applying the first time delay; and

a first fractional delay comprising a first number of filters for applying the second time delay,

wherein the first integer delay and the first fractional delay respectively apply the first time delay and the second time delay to temporally align the input signal with the feedback signal,

wherein the controller determines a first Measure of Error (ME) for each of the first number of filters using one equation selected from among the following equations;

8. The apparatus of claim 7, wherein the controller further determines a minimum ME from among the determined first MEs, and wherein the first fractional delay uses the first filter corresponding to the minimum first ME as the second time delay.

9. The apparatus of claim 7, wherein the controller determines a third time delay between the input signal and the feedback signal and determines a fourth time delay between the input signal and the feedback signal, the determination of the fourth time delay having a higher resolution than the determination of the third time delay, and wherein

a second integer delay applies the third time delay;

and

a second fractional delay applies the second time delay,

wherein the second integer delay and the second fractional delay respectively apply the third time delay and the fourth time delay to temporally align an envelope signal with a forward path signal.

10. The apparatus of claim 9, wherein the controller determines a number of second filters with which to determine the fourth time delay.

11. The apparatus of claim 10, wherein the controller determines a second ME for each of the second filters and determines a minimum ME from among the determined second MEs, and wherein the second fractional delay uses the second filter corresponding to the minimum second ME as the fourth time delay.

12. The apparatus of claim 7 wherein the controller creates a Finite Impulse Response (FIR) filter, sequentially loads the FIR filter with each of the first filters, sequentially passes the captured feedback signal through the FIR filter loaded with the first filters to determine an output corresponding to each of the first filters, determines a ME corresponding to each of the first filters using the output of the FIR filter and the input signal, and determines a minimum ME from among the determined MEs.