Closed loop calibration for an amplitude reconstruction amplifier

• US 6,215,354 B1
• Filed: 02/05/1999
• Issued: 04/10/2001
• Est. Priority Date: 03/06/1998
• Status: Expired due to Fees

• Current Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Original Assignee: Fujant, Inc. (CommScope Holding Company, Inc.)
• Inventors: Shynk, John J., Baseghi, Behshad, Kolanek, James C.
• Primary Examiner(s): Mottola, Steven J.
• Application Number:
  US09/245,504
• Time in Patent Office: 795 Days
• Field of Search: 330/2, 330/124.R, 330/126, 330/149, 330/304
• US Class Current: 330/2
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 1/0294 using vector summing of two or more constant amplitude phase-modulated signals
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3252 using multiple parallel paths between input and output H03F1/3258, H03F1/3282, H03F1/3294 take precedence
• CPC Class Codes: H03F 1/3282 Acting on the phase and the amplitude of the input signal
• CPC Class Codes: H03F 1/3288 to compensate phase shift as a function of the amplitude
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit
• CPC Class Codes: H03F 2201/3233 Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion
• CPC Class Codes: H03F 2203/7215 the gated amplifier being switched on or off by a switch at the input of the amplifier
• CPC Class Codes: H03F 2203/7236 the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers by (a ) switch(es)
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/602 Combinations of several amplifiers
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H04B 1/0483 Transmitters with multiple parallel paths

Abstract

A calibration method and apparatus for calibrating and linearizing an amplifier in which an input signal is decomposed into N channels. Then the amplifier is modeled to generate an estimated amplifier transfer function for each channel. Using the estimated amplifier transfer function for each channel, equalizer values are computed for equalizers that are applied to each channel prior to amplification, thus enabling the amplification of amplitude and/or phase modulated signals via the non-linear amplifiers.

Claims

1. A calibration method for calibrating an amplifier comprising:

decomposing the input signal into a channel pair by applying a nonlinear function to the input signal;

modeling the amplifier to generate an estimated amplifier transfer function for each of N channels processing a decomposed version of an input signal; and

computing equalizer values for equalizers that are applied to each of the N channels prior to amplification, wherein the computing of equalizer values are based on the estimated amplifier transfer function for each channel in conjunction with a plurality of error criteria combined with weighting from each of the plurality of error criteria.

2. The method defined in claim 1 wherein the N channels comprises a channel pair.

3. The method defined in claim 1 further comprising reducing the expected error between the amplifier and a model of the amplifier.

4. The method defined in claim 3 further comprising wherein the model is linear.

5. The method defined in claim 1 further comprising reducing the expected error between the amplifier and a linear model of the amplifier using the estimated amplifier transfer function for each channel.

6. A calibration method for calibrating an amplifier comprising:

modeling the amplifier to generate an estimated amplifier transfer function for each of N channels processing a decomposed version of an input signal; and

modeling the amplifier transfer functions as multiple FIR filters; and

computing equalizer values for equalizers that are applied to each of the N channels prior to amplification, wherein the computing of equalizer values are based on the estimated amplifier transfer function for each channel in conjunction with a plurality of error criteria combined with weighting from each of the plurality of error criteria.

7. A calibration method for calibrating an amplifier comprising:

modeling the amplifier to generate an estimated amplifier transfer function for each of N channels processing a decomposed version of an input signal; and

computing equalizer values for equalizers that are applied to each of the N channels prior to amplification. wherein the computing of equalizer values are based on the estimated amplifier transfer function for each channel in conjunction with a plurality of error criteria combined with weighting from each of the plurality of error criteria wherein computing values comprises computing equalizer FIR tap values using amplifier model FIR tap values.

8. A calibration apparatus for calibrating an amplifier comprising:

means for decomposing an input signal into N channels;

means for modeling the amplifier to generate an estimated amplifier transfer function for each of the N channels; and

means for computing equalizer values for equalizers that are applied to each of the N channels in the channel pair prior to amplification, wherein the computing of equalizer value is based on the estimated amplifier transfer function for each channel.

9. The apparatus defined in claim 8 wherein the means for decomposing the input signal comprises means for applying a nonlinear function to the input signal.

10. The apparatus defined in claim 8 further comprising means for reducing the expected error between the amplifier and a linear model of the amplifier.

11. The apparatus defined in claim 8 further comprising means for reducing the expected error between the amplifier and a linear model of the amplifier using the estimated amplifier transfer function for each channel.

12. The apparatus defined in claim 8 further comprising means for minimizing the expected error between the amplifier and a linear model of the amplifier.

13. The apparatus defined in claim 8 wherein the amplifier transfer functions comprise model FIR tap values.

14. The apparatus defined in claim 8 further comprising means for computing equalizer FIR tap values using amplifier model FIR tap values.

15. An architecture for calibration and equalization of an amplifier comprising:

a linear model of the amplifier having estimated linear transfer functions that are estimates of the actual transfer functions of the amplifier; and

a controller coupled to the linear model and the amplifier to set up the equalizers in the amplifier based on the response of the linear model to calibrate the amplifier, wherein the controller generates FIR coefficients to set up the equalizers.

16. The architecture defined in claim 15 wherein the model amplifier models the estimated amplifier transfer functions as multiple FIR filters.

17. The architecture defined in claim 15 wherein the controller determines FIR coefficients based on the response of the multiple FIR filters in the system.

18. The architecture defined in claim 15 wherein the controller generates the estimated amplifier transfer functions and uses the estimated amplifier transfer functions to estimate the equalization necessary to balance the channels.