Method for correcting DC offsets in a receiver

• US 6,717,995 B2
• Filed: 12/23/2002
• Issued: 04/06/2004
• Est. Priority Date: 05/12/1999
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Zvonar, Zoran
• Primary Examiner(s): Ghayour, Mohammad H.
• Assistant Examiner(s): Nguyen, Dung X.
• Application Number:
  US10/328,275
• Publication Number:
  US 20030099310A1
• Time in Patent Office: 470 Days
• Field of Search: 375/340, 375/346, 375/263, 375/285, 375/406.09, 375/319, 375/317, 375/342
• US Class Current: 375/340
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/0242 using matrix methods
• CPC Class Codes: H04L 25/025 using least-mean-square [LMS] method
• CPC Class Codes: H04L 25/061 providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset removal of dc offset in coupling arrangements H04L25/029, H04L25/0296

Abstract

A method for reducing DC offset from a receiver signal. The method includes jointly (i.e., simultaneously) estimating such DC offset and channel impulse response, and reducing the DC offset in accordance with the estimated DC offset and the estimate of the channel impulse response.

Claims

1. A method of compensating for DC offset in a receiver, said method comprising:

receiving a signal burst from a transmitter device;

storing said signal burst in a memory device;

performing joint and simultaneous Minimum Mean Square Error optimization with respect to a DC offset and a channel impulse associated with said signal burst so that a computed DC offset and a computed channel impulse are generated;

subtracting from said signal burst said computed DC offset forming a second signal burst indicative of said DC offset being removed from said signal burst; and

using said computed channel impulse to equalize said second signal burst so as to compute modulated components of said received signal burst.

2. The method of claim 1, wherein said signal burst is defined as $r$

(k)=A+∑

b

(n)

h

(k-n)+N

(k)

where A is said DC offset, b(n) are data symbols, h(k) is said channel impulse, k is a time index, and N(k) is thermal noise.

3. The method of claim 2, wherein said Minimum Mean Square Error optimization is defined as $\frac{\partial }{}$

(f

(e

(k)))∂

A^

 

=0

 



and

 



∂

(f

(e

(k)))∂

h^=0

where e(k) is an error function, f(e(k)) is a Minimum Mean Square Error function, Â

is the computed DC offset, and ĥ

is the computed channel impulse.

4. The method of claim 2, wherein said computed DC offset is a statistical average of

5. The method of claim 2, wherein said computed channel impulse is defined as

8. The apparatus of claim 2, wherein said Minimum Mean Square Error optimization is defined as $\frac{\partial }{}$

(f

(e

(k)))∂

A^

 

=0

 



and

 



∂

(f

(e

(k)))∂

h^=0

where e(k) is an error function, f(e(k)) is a Minimum Mean Square Error function, Â

is the computed DC offset, and ĥ

is the computed channel impulse.

6. An apparatus for reducing DC offset in a receiver comprising:

a data receiver that receives a signal burst from a transmitter device, said data receiver storing said signal burst in a memory device; and

a DSP device that performs joint and simultaneous Minimum Mean Square Error optimization with respect to a DC offset and a channel impulse associated with said signal burst so that a computed DC offset and a computed channel impulse are generated, wherein

said DSP device subtracting from said signal burst said computed DC offset forming a second signal burst indicative of said DC offset being removed from said signal burst and using said computed channel impulse to equalize said second signal burst so as to compute modulated components of said received signal burst.

7. The apparatus of claim 6, wherein said signal burst is defined as $r$

(k)=A+∑

b

(n)

h

(k-n)+N

(k)

where A is said DC offset, b(n) are data symbols, h(k) is said channel impulse, k is a time index, and N(k) is thermal noise.

9. The apparatus of claim 7, wherein said computed DC offset is a statistical average of

10. The apparatus of claim 7, wherein said computed channel impulse is defined as