WO1995005030B1

WO1995005030B1 - Adaptive equalizer circuit

Info

Publication number: WO1995005030B1
Application number: PCT/US1994/008911
Authority: WO
Filing date: 1994-08-03
Publication date: 1995-03-30

Abstract

An adaptive equalizer is configured to reconstruct electronic signals which are transmitted over signal cables, such as twisted pair cables. The equalizer satisfactorily reconstructs the signals over a broad range of cable lengths. The degradation characteristics of a signal cable varies with cable length. Using the degradation characteristics for a cable over a desired range of lengths, the adaptive equalizer includes multiple parallel paths (144, 146) each of which are configured to reconstruct the input voltage signal optimized for a particular cable length. The degraded input signal is split (140) according to a predetermined relationship into multiple partial signals, each signal for transmission through one each of the paths (144, 146). Though each path (144, 146) is optimized to reconstruct the signal for a particular length of cable, the adaptive control (144) adds a function of the actual cable length for more accurately reconstructing the signal. Each path (144, 146) forms a partial reconstructed signal. In the preferred embodiment, there are two paths (144, 146) one of which does not modify its partial signal. The partial signals from each path are summed (148) to form a composite reconstructed signal.

Claims

AMENDED CLAIMS[received by the International Bureau on 20 February 1995 (20.02.95); original claims 1-14 replaced by amended claims 1-14 (3 pages)]

1. An adaptive equalizer comprising: a. means for receiving an input signal; b. means for splitting the input signal into a first partial signal and a second partial signal; c. means for adjusting the first partial signal according to a predetermined first function for forming a reconstructed first partial signal; and d. means for summing the reconstructed first partial signal and the second partial signal for forming a reconstructed output signal.

2. The adaptive equalizer according to claim 1 wherein the means for splitting divides the input signal into the first partial signal and the second partial signal according to a predetermined relationship to a signal cable length.

3. The adaptive equalizer according to claim 2 wherein the means for splitting divides the input signal into portions related to M for the first partial signal and 1-M for the second partial signal.

4. The adaptive equalizer according to claim 3 wherein the means for adjusting the first partial signal follows the ratio N(s)/D(s) such that the ratio of the reconstructed output signal to the input signal follows the relationship:

^yn -_M / M s) _{) +} . __M) _ M(N( S) -D ( s) ) +D { S) V₁₀ D ( s) D ( S)

5. An adaptive equalizer comprising: a. means for receiving an input signal; b. means for splitting the input signal into a first partial signal and a second partial signal; c. means for adjusting the first partial signal according to a predetermined first function for forming a reconstructed first partial signal;

34 d. means for adjusting the second partial signal according to a predetermined second function for forming a reconstructed second partial signal; and e. means for summing the reconstructed first partial signal and the second reconstructed partial signal for forming a reconstructed output signal.

6. The adaptive equalizer according to claim 5 wherein the predetermined second function leaves the second partial signal unchanged.

7. The adaptive equalizer according to claim 6 wherein the means for splitting divides the input signal into the first partial signal and the second partial signal according to a predetermined relationship to a signal cable length.

8. The adaptive equalizer according to claim 7 wherein the means for splitting divides the input signal into portions related to M for the first partial signal and 1 -M for the second partial signal.

9. The adaptive equalizer according to claim 8 wherein the means for adjusting the first partial signal follows the ratio N(s)/D(s) such that the ratio of the reconstructed output signal to the input signal follows the relationship:

10. An adaptive filter comprising: a. means for receiving an input signal; b. means for splitting the input signal into a plurality of partial signals; c. means for adjusting each of the partial signals according to one each of a plurality of predetermined functions for forming a plurality of reconstructed partial signals, one for each of the plurality of partial signals; and d. means for summing the plurality of reconstructed partial signals for forming a reconstructed output signal.

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1 1. An adaptive equalizer comprising: a. a splitter for receiving an input voltage signal; b. an adaptive controller circuit for controlling the splitter to split the input voltage signal into a first partial signal and a second partial signal according to a predetermined relationship; c. a first path coupled to receive the first partial signal having a first transconductor having a capacitive feedback, a second transconductor coupled to receive a first output signal from the first transconductor, the second transconductor having a zero impedance feedback path, a third transconductor coupled to receive a second output signal from the second transconductor, the third transconductor having a capacitive feedback, and a fourth transconductor coupled to receive a third output signal from the third transconductor; and d. a summing circuit coupled to receive a fourth output signal from the fourth transconductor and coupled to receive the second partial signal for forming a reconstructed output signal.

12. The adaptive equalizer according to claim 11 wherein the means for splitting divides the input signal into the first partial signal and the second partial signal according to a predetermined relationship to a signal cable length.

13. The adaptive equalizer according to claim 12 wherein the means for splitting divides the input signal into portions related to M for the first partial signal and 1-M for the second partial signal.

14. The adaptive equalizer according to claim 13 wherein the means for adjusting the first partial signal follows the ratio N(s) D(s) such that the ratio of the reconstructed output signal to the input signal follows the relationship:

^yn -_H( M s) _{) + { 1} __M) _ M{N( s) -D ( s) ) +D ( s)

V 1, 0 D ( s) D ( S)

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STATEMENT UNDER ARTICLE 19

The examiner indicated that claim 5 cannot be considered novel or to involve an inventive step over Chung and claims 1 and 10 cannot be considered novel or to involve an inventive step over Cummins or Harris. The applicant respectfully disagrees.

The present invention as claimed in amended claims 1, 5, and 10, is an adaptive equalizer comprising means for splitting the input signal into partial signals. The input signal is divided into portions (page 7, lines 13-15 and page 20, lines 13-16) by the splitter 140, 240. These portions are called "partial signals" (page 4, lines 1-3). Note that Figure 8 shows a circuit schematic of such a splitter.

In contrast, Chung, in Figure 3 shows that the input signal 94 is not divided into portions, but rather identical signals are applied directly to each of the filter 62, summing junction 156 and delay 154. The difference is that Chung does not disclose the claimed splitting means of the present invention.

Further, in Chung, some signals are added together at summing junction 160, then subtracted at the summing junction 86 from the filtered input signal d(j) to form the output signal e(j). In contrast, the present invention, adds the reconstructed partial signals to arrive at the reconstructed output signal. The difference is that Chung does not disclose the claimed summing means of the present invention.

Also in contrast, Cummins, in Figure 2 shows that the input signal is not divided into portions, but rather identical signals are applied directly to each of the estimators 24- 26 and summing junction 22. The difference is that Cummins does not disclose the claimed splitting means of the present invention.

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Further, in Cummins, some inputs to the summing junction are subtracted from the input signal to form the output signal. In contrast, the present invention, adds the reconstructed partial signals to arrive at the reconstructed output signal. The difference is that Cummins does not disclose the claimed summing means of the present invention.

Also in contrast to the present invention, Harris, in Figure 8 shows that the input signal is not divided into portions, but rather identical signals are applied directly to each of the summing network 703 and delay circuit 702. The difference is that Harris does not disclose the claimed splitting means of the present invention.

Further, in Harris, some inputs to the summing junction are added together at 705, then subtracted from the input signal at 703 to form the output signal. In contrast, the current invention, adds the reconstructed partial signals to arrive at the reconstructed output signal. The difference is that Harris does not disclose the claimed summing means of the present invention.

The examiner referred to Figure 7, item #8, of Harris. The applicant believes that the examiner intended to refer to Figure 8, item #701. The applicant believes that the analog-to-digital converter 701 does not disclose the splitting means of the present invention. Note that the differences include that the converter 701 produces a single output signal (a digital value), whereas the splitter 140, 240 of the present invention produces more than one output signal (the partial signals).

For at least these reasons, the applicant believes claims 1, 5 and 10 are now allowable.

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