Calibrating transition dependent timing errors in automatic test equipment using a precise pulse width generator
AssigneeTexas Instruments Incorporated
InventorMarc R. Mydill
Life of this patent
Estimating the term…
Abstract
A calibration method and system for substantially reducing one of the components of timing error in automatic test systems. The timing associated with digital stimulus and response circuitry in a tester is different for positive and negative signal transitions. This inherent timing difference is normally measured and compensated for during the tester calibration process. The present method and system uses a short circuited transmission line as a pulse generator to achieve superior stability and accuracy when calibrating transition dependent timing in automatic test systems.
Claims5
A method of calibrating transition dependent equipment timing errors, comprising the steps of:
- generating an incident signal onto a short circuited transmission line to ground;
- measuring a time difference measurement between said incident signal and a reflection of said incident signal resulting from generation of said reference signal onto said short circuited transmission line;
- determining the difference between said time difference measurement and a known pulse width of said short circuited transmission line to provide an indication of the transition-dependent error of said time difference measurement;
- and
- compensating subsequent pulse width measurements in response to said indicating the transition-dependent error.
A system for calibrating transition dependent equipment timing errors comprising:
- a short circuited transmission line to ground and having a known length;
- an incident signal source for generating and reflecting an incident signal onto said short circuited transmission line;
- a time measurement reference unit for measuring a time difference between said incident signal and said reflection of said incident signal resulting from said generation of said incident signal onto said short circuited transmission line to said ground;
- circuitry to disconnect said short circuited transmission line from said time measurement reference unit;
- and
- circuitry to connect another signal source to said time measurement reference unit to achieve said calibration.
Dependencies are inferred from the claim text.