APPARATUS AND METHOD FOR MEASURING SKEW IN SERIAL DATA COMMUNICATION

• US 20090055694A1
• Filed: 08/12/2008
• Published: 02/26/2009
• Est. Priority Date: 08/22/2007
• Status: Abandoned Application

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: OBATA, Tetsuo, RAMESH, P. E.
• Application Number:
  US12/190,404
• Publication Number:
  US 20090055694A1
• Time in Patent Office: Days
• US Class Current: 714/700
• CPC Class Codes: G01R 31/3171 BER [Bit Error Rate] test
• CPC Class Codes: G01R 31/31726 Synchronization, e.g. of test, clock or strobe signals; Signals in different clock domains; Generation of Vernier signals; Comparison and adjustment of the signals
• CPC Class Codes: H04L 25/14 Channel dividing arrangements , i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver

Abstract

An apparatus and method measures the skew between signals on data and clock channels using a bit pattern matching technique for any given protocol in Serial data communication. In one embodiment, the method of finding the pattern comprises of importing the waveform data from the oscilloscope and converting the waveform into bit patterns, finding the pattern index on the converted bit stream using a pattern based on the TMDS channel combination, and then measuring the skew.

Claims

1. A method to measure skew between signals on channels in serial data communication comprising the step of:

finding the cross over points in an acquired signal from each of the combination of channels under test;

converting the acquired signals into bit patterns;

identifying bit pattern index of the converted bit patterns matching with a reference bit pattern;

converting the bit pattern index of each of the identified matching bit patterns into record point;

calculating the time difference between said record points on different channels to derive the skew value.

2. The method as in claim 1 wherein the acquisition of said acquired signal is done using probes on the combination of channels between which the skew needs to be measured.

3. The method as in claim 1, wherein the identification of the crossover in the acquired signal is done by finding the edge in the acquired signal.

4. The method as in claim 1, wherein each of the steps of:

finding the cross over points in an acquired signal from each of the combination of channels under test;

converting the acquired signals into bit patterns;

identifying bit pattern index of the converted bit patterns matching with a reference bit pattern; and

converting the bit pattern index of each of the identified matching bit patterns into record point;

takes place substantially simultaneously for each of the channels.

5. The method as in claim 1, wherein each of the steps of:

finding the cross over points in an acquired signal from each of the combination of channels under test;

converting the acquired signals into bit patterns;

identifying bit pattern index of the converted bit patterns matching with a reference bit pattern; and

converting the bit pattern index of each of the identified matching bit patterns into record point;

takes place consecutively for each of the channels.

6. The method as in claim 1, wherein the conversion of the index of the identified matching bit pattern into record further comprises the steps of:

converting the bit pattern index of each of the identified matching bit patterns into waveform record;

finding the time value of such index using the sample interval information.

The method as in claim 1, wherein the conversion of the acquired signals into bit patterns is performed using cross over edge Tbit interval technique.

7. A system for finding skew between channels in a serial data communication, the system comprising:

input means to acquire signals from a combination of channels to be tested;

a programming unit configured to convert the acquired signal from each of the channel into bit patterns;

said programming unit also configured to identify the bit pattern matching with a reference bit pattern to identify the index of such identified bit patterns and calculate the skew between such indexes.