System and method of multi-channel signal calibration

• US 7,796,068 B2
• Filed: 07/16/2008
• Issued: 09/14/2010
• Est. Priority Date: 07/16/2007
• Status: Expired due to Fees

• Current Assignee: Gil M. Raz
• Original Assignee: Gmr Research & Technology, Inc.
• Inventors: Jackson, Jeffrey H., Raz, Gil M.
• Primary Examiner(s): JEANGLAUDE, JEAN BRUNER
• Application Number:
  US12/218,619
• Publication Number:
  US 20090033529A1
• Time in Patent Office: 790 Days
• Field of Search: 341117-120
• US Class Current: 341/120
• CPC Class Codes: H03M 1/1033 over the full range of the converter, e.g. for correcting differential non-linearity
• CPC Class Codes: H03M 1/1215 using time-division multiplexing

Abstract

A signal processing system for reducing calibration-related distortions in a complete-channel signal generated by a multi-channel subsystem, such as an interleaved ADC, includes a channel separator for separating the distorted digital signal into its various sub-channels and a single-channel corrector for independently processing each sub-channel to reduce distortion products present therein. The system additionally includes a subchannel re-combiner for combining the plurality of sub-channels processed by the single-channel corrector and a multi-channel corrector for calibrating each of plurality of sub-channels relative to one another to yield an equalized, complete-channel output signal. The multi-channel corrector includes a bank of optimized filters, each filter being assigned to a corresponding sub-channel of the complete-channel signal. In one embodiment, one of the plurality of sub-channels is selected as an ideal reference signal and the filters assigned to the remaining sub-channels are optimized to yield outputs which match the ideal reference signal.

Claims

1. A signal processing system comprising:

(a) a multi-channel subsystem for converting a set of analog input signals into an unequalized, digitized complete-channel output signal which includes a plurality of sub-channels, and

(b) an equalization subsystem for calibrating the unequalized, digitized complete-channel output signal to yield an equalized, digitized complete-channel output signal,

(c) wherein the equalization subsystem comprises a multi-channel corrector for calibrating the individual sub-channels of the unequalized, digitized complete-channel output signal relative to one another, the multi-channel corrector comprising a plurality of filters, each of the plurality of filters being assigned to calibrate a corresponding sub-channel using all sub-channel data from the unequalized, digitized complete-channel output signal.

2. The signal processing system as claimed in claim 1 wherein the multi-channel corrector calibrates the individual sub-channels of the unequalized, digitized complete-channel output signal relative to one another to treat interleaving errors present therein.

3. The signal processing system of claim 1 wherein each filter includes an equalization coefficient which has a linear correspondence with at least one of the unequalized, digitized complete-channel output signal and the equalized, digitized complete-channel output signal.

4. The signal processing system of claim 3 wherein the equalization subsystem further comprises:

(a) means for separating the complete-channel signal filtered by the multi-channel corrector into its plurality of sub-channels,

(b) a channel offset corrector for adding a constant DC offset term to each sub-channel, and

(c) means for combining the processed sub-channels together to create the equalized complete-channel output signal.

5. The signal processing system of claim 3 wherein the equalization subsystem further comprises:

(a) a channel separator for separating the unequalized complete-channel output signal into its plurality of sub-channels, each sub-channel including at least one distortion product,

(b) a single-channel corrector for independently treating each of the plurality of sub-channels to reduce the at least one distortion product present therein, and

(c) a subchannel re-combiner for combining the plurality of sub-channels processed by the single-channel corrector to yield a partially equalized, complete-channel digital signal which is then passed, in its entirety, into the multi-channel corrector.

6. The signal processing system of claim 5 wherein the single-channel corrector comprises a plurality of single-channel equalization elements, each equalization element being designated to treat signal distortions present within a corresponding sub-channel of the unequalized complete-channel signal.

7. A method of processing an unequalized complete-channel output signal produced from a multi-channel subsystem, the complete-channel output signal including a plurality of sub-channels, the method comprising the steps of:

(a) providing a multi-channel corrector, the multi-channel corrector comprising a plurality of filters, each of the plurality of filters being assigned to calibrate a corresponding sub-channel,

(b) passing the unequalized complete-channel signal in its entirety into each filter of the a multi-channel corrector, and

(c) calibrating each of the plurality of sub-channels relative to one another using the corresponding filter in the multi-channel corrector.

8. The method as claimed in claim 7 wherein each of the plurality of filters has an equalization coefficient.

9. The method as claimed in claim 8 further comprising the step of, prior to said calibration step, optimizing the value of the equalization coefficient for each filter.

10. The method as claimed in claim 9 wherein said optimization step comprises the following steps:

(a) injecting at least one known excitation signal into the multi-channel subsystem to yield a measured, complete-channel output signal,

(b) selecting an ideal reference signal for calculating the value of the equalization coefficient for each filter using the measured, complete-channel signal, and

(c) calculating an equalization coefficient for each filter such that its corresponding sub-channel generates an output signal which matches the ideal reference signal.

11. The method as claimed in claim 10 wherein, in the selecting step, one of the plurality of sub-channels is utilized as the ideal reference signal.

12. The method as claimed in claim 10 wherein, in the injecting step, a tonal signal is used as the at least one excitation signal.

13. The method as claimed in claim 9 further comprising the steps of, after said calibrating step:

(a) separating the complete-channel output signal filtered by the plurality of filters in the multi-channel corrector into its plurality of sub-channels,

(b) adding a constant DC offset term to each of the plurality of sub-channels, and

(c) combining the resultant sub-channels together to create the equalized complete-channel output signal.

14. The method as claimed in claim 9 further comprising the steps of, prior to said passing step:

(a) separating the unequalized complete-channel output signal into its plurality of sub-channels, each sub-channel including at least one distortion product, and

(b) independently treating each of the plurality of sub-channels to reduce the at least one distortion product present therein.