Capturing and evaluating high speed data streams

A method of programming a tester to capture a serial data stream from the output of a SerDes device, comprising:

• A) determining a vector period to be used for applying input data to the SerDes device at a desired word rate;
• B) computing a number (P) of times the serial data stream must be repeated to sample each desired location of the serial data stream using the vector period determined in step A;
• C) determining an integer number (N) of tester timing sets (TSETs) to be used in sampling all desired locations of the serial data stream, wherein N is divisible by P;
• D) determining an integer number (M) of times said N TSETs are to be reused in sampling the serial data stream, wherein M equals P divided by N;
• and
• E) programming the tester with the vector period, test vectors, number of TSETs, and number of times the TSETs are reused.

In an automatic test system, an apparatus for testing a device under test (DUT) that generates a serial output signal, comprising:

• a plurality of driver circuits, a portion of said plurality of driver circuits being coupled to the DUT to stimulate the DUT to generate a serial output signal;
• a latching device having a signal input coupled to the output of the DUT for receiving the serial output signal, an enable input coupled to one of the plurality of driver circuits for activating the latching device, and an output coupled to a memory for storing digital values provided at the output of the latching device;
• a timing generator for causing the driver circuit coupled to the enable input of the latching device to activate the enable input at predetermined instants of time relative to the serial output signal;
• and
• means for determining a probability of the serial output signal from the stored values.