Method and system for fast calibration to cancel phase feedthrough

• US 7,436,253 B2
• Filed: 12/27/2006
• Issued: 10/14/2008
• Est. Priority Date: 12/06/2006
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Zolfaghari, Alireza
• Primary Examiner(s): Pascal; Robert J.
• Assistant Examiner(s): Nguyen; Khiem D
• Application Number:
  US11/616,689
• Publication Number:
  US 20080136511A1
• Time in Patent Office: 657 Days
• Field of Search: 330/2, 330/9, 330/51, 330/124.R, 330/136, 330/295
• US Class Current: 330/2
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 1/32 Modifications of amplifiers to reduce non-linear distortion by negative feedback H03F1/34
• CPC Class Codes: H03F 2200/105 A non-specified detector of the power of a signal being used in an amplifying circuit
• CPC Class Codes: H03F 2200/375 Circuitry to compensate the offset being present in an amplifier
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control

Abstract

Methods and systems for fast calibration to cancel phase feedthrough are disclosed and may comprise individually activating each of n binary-weighted cells utilizing a control signal in a power amplifier driver (PAD) and measuring the output signal, or offset, in response to a null signal applied to an input of each binary-weighted cell. This offset may be fed back, summed, and adjusted until the measured PAD output may be minimized. This calibrated offset may cancel phase feedthrough of the PAD, and the calibrated offset for each binary-weighted cell may be stored in a lookup table. The control signal may also be utilized for controlling the output power of the PAD by activating appropriate binary-weighted cells. For each of the 2ⁿ output powers, a calibrated offset is calculated utilizing a weighted sum of the stored offsets for the activated binary-weighted cells.

Claims

1. A method for calibrating and using a circuit, the method comprising:

in a power amplifier driver (PAD) comprising n binary-weighted cells, individually activating each of said n binary-weighted cells, one at a time, utilizing a control signal, and wherein n is an integer;

responsive to an input signal applied to an input of each of said individually activated n binary-weighted cells, measuring corresponding output signals generated at an output of said PAD to determine an offset; and

for each of said individually activated n binary-weighted cells, feeding back and adjusting said determined offset to an input of said PAD until a measured output of said PAD is minimized.

2. The method according to claim 1, comprising combining said fed back determined offset with a zero input of said PAD.

3. The method according to claim 1, wherein said adjusted offset cancels a phase feedthrough of said PAD.

4. The method according to claim 1, wherein said control signal is also utilized for controlling an output power of said PAD.

5. The method according to claim 1, comprising for each of said individually activated n binary-weighted cells, storing in a lookup table said adjusted offset that causes said output of said PAD to be minimized.

6. The method according to claim 5, comprising determining an output power level of said PAD based on a number of said n binary-weighted cells activated by said control signal.

7. The method according to claim 6, comprising calculating an offset for said output power level of said PAD based on at least said stored adjusted offset for said number of said n binary-weighted cells activated by said control signal.

8. The method according to claim 6, comprising calculating an offset for said output power level of said PAD based on a weighted sum of said stored adjusted offset for said number of said n binary-weighted cells activated by said control signal.

9. The method according to claim 6, comprising calculating said output power level of said PAD utilizing the following equation:

$\frac{\underset{k=0}{\overset{n-1}{\sum <br><br>}}<br><br><br><br>2^k<br><br>\mathrm{•<br><br>}<br><br><br><br>\mathrm{pc}<<br><br>k><br><br>\mathrm{•<br><br>}<br><br><br><br>{\mathrm{\Delta <br><br>}}_k}{\mathrm{pc}}$

where pc<

k >

is equal to 1 if a k-th binary-weighted cell is activated or is equal to 0 if a k-th binary-weighted cell is not activated, pc is said control signal, and Δ

_k is said stored adjusted offset of the k-th binary-weighted cell in said lookup table.

10. The method according to claim 1, wherein a number of possible output levels of said PAD is 2ⁿ.

11. A system for calibrating and using a circuit, the system comprising:

a power amplifier driver (PAD) comprising n binary-weighted cells, said n binary-weighted cells being individually activated one at a time utilizing a control signal, and wherein n is an integer;

one or more circuits responsive to an input signal applied to an input of each of said individually activated n binary-weighted cells, said one or more circuits measuring corresponding output signals generated at an output of said PAD to determine an offset; and

said one or more circuits, for each of said individually activated n binary-weighted cells, feeding back and adjusting said determined offset to an input of said PAD until a measured output of said PAD is minimized.

12. The system according to claim 11, comprising one or more circuits for combining said fed back determined offset with a zero input of said PAD.

13. The system according to claim 11, comprising one or more circuits for canceling a phase feedthrough of said PAD utilizing said adjusted offset.

14. The system according to claim 11, comprising one or more circuits for controlling an output power of said PAD utilizing said control signal.

15. The system according to claim 11, comprising one or more circuits for storing in a lookup table for each of said individually activated n binary-weighted cells, said adjusted offset that causes said output of said PAD to be minimized.

16. The system according to claim 15, comprising one or more circuits for determining an output power level of said PAD based on a number of said n binary-weighted cells activated by said control signal.

17. The system according to claim 16, comprising one or more circuits for calculating an offset for said output power level of said PAD based on at least said stored adjusted offset for said number of said n binary-weighted cells activated by said control signal.

18. The system according to claim 16, comprising one or more circuits for calculating an offset for said output power level of said PAD based on a weighted sum of said stored adjusted offset for said number of said n binary-weighted cells activated by said control signal.

19. The system according to claim 16, comprising one or more circuits for calculating said output power level of said PAD utilizing the following equation:

$\frac{\underset{k=0}{\overset{n-1}{\sum <br><br>}}<br><br><br><br>2^k<br><br>\mathrm{•<br><br>}<br><br><br><br>\mathrm{pc}<<br><br>k><br><br>\mathrm{•<br><br>}<br><br><br><br>{\mathrm{\Delta <br><br>}}_k}{\mathrm{pc}}$

where pc<

k>

is equal to 1 if a k-th binary-weighted cell is activated or is equal to 0 if a k-th binary-weighted cell is not activated, pc is said control signal, and Δ

_k is said store adjusted offset of the k-th binary-weighted cell in said lookup table.

20. The system according to claim 11, comprising one or more circuits wherein a number of possible output levels of said PAD is 2ⁿ.

21. A machine-readable storage medium having stored thereon, a computer program having at least one code section for calibrating and using a circuit, the at least one code section being executable by a machine for causing the machine to perform steps comprising:

in a power amplifier driver (PAD) comprising n binary-weighted cells, individually activating each of said n binary-weighted cells, one at a time, utilizing a control signal, and wherein n is an integer;

responsive to an input signal applied to an input of each of said individually activated n binary-weighted cells, measuring corresponding output signals generated at an output of said PAD to determine an offset;

for each of said individually activated n binary-weighted cells, feeding back and adjusting said determined offset to an input of said PAD until a measured output of said PAD is minimized.

22. The machine readable storage medium according to claim 21, wherein said at least one code section comprises code for combining said fed back determined offset with a zero input of said PAD.

23. The machine readable storage medium according to claim 21, wherein said at least one code section comprises code for canceling a phase feedthrough of said PAD utilizing said adjusted offset.

24. The machine readable storage medium according to claim 21, wherein said at least one code section comprises code for controlling an output power of said PAD utilizing said control signal.

25. The machine readable storage medium according to claim 21, wherein said at least one code section comprises code for storing in a lookup table for each of said individually activated n binary-weighted cells, said adjusted offset that causes said output of said PAD to be minimized.

26. The machine readable storage medium according to claim 25, wherein said at least one code section comprises code for determining an output power level of said PAD based on a number of said n binary-weighted cells activated by said control signal.

27. The machine readable storage medium according to claim 26, wherein said at least one code section comprises code for calculating an offset for said output power level of said PAD based on at least said stored adjusted offset for said number of said n binary-weighted cells activated by said control signal.

28. The machine readable storage medium according to claim 26, wherein said at least one code section comprises code for calculating an offset for said output power level of said PAD based on a weighted sum of said stored adjusted offset for said number of said n binary-weighted cells activated by said control signal.

29. The machine readable storage medium according to claim 26, wherein said at least one code section comprises code for calculating said output power level of said PAD utilizing the following equation:

$\frac{\underset{k=0}{\overset{n-1}{\sum <br><br>}}<br><br><br><br>2^k*<br><br>\mathrm{pc}<<br><br>k><br><br>*<br><br>{\mathrm{\Delta <br><br>}}_k}{\mathrm{pc}}$

where pc<

k>

is equal to 1 if a k-th binary-weighted cell is activated or is equal to 0 if a k-th binary-weighted cell is not activated, pc is said control signal, and Δ

_k is said stored adjusted offset of the k-th binary-weighted cell in said lookup table.

30. The machine readable storage medium according to claim 21, wherein said at least one code section comprises code wherein a number of possible output levels of said PAD is 2ⁿ.