Deskewed differential detector employing analog-to-digital converter
AssigneeTeradyne, Inc.
InventorMichael C. Panis
Life of this patent
Estimating the term…
Abstract
A pin electronics circuit for automatic test equipment includes first and second sampling circuits for sampling first and second legs of a differential signal produced by a DUT (Device Under Test). Timing signals activate the first and second sampling circuits to sample the legs of the differential signal at precisely defined instants of time to produce first and second collections of samples. To deskew the legs of a differential signal with respect to each other, corresponding features within the first and second collections are identified and a difference is taken between them. The differential skew can then be applied to correct measurements of differential signals.
Claims20
An automatic test system for testing a device under test (DUT), comprising:
- at least one sampling circuit connectable to the DUT for receiving first and second legs of a differential signal and for sampling said first and second legs at predetermined instants of time defined by first and second timing signals, respectively,
- at least one memory for storing samples acquired by the at least one sampling circuit;
- first and second variable delay circuits for respectively delaying the first and second timing signals enroute to the at least one sampling circuit;
- and
- a processor, coupled to the at least one memory and to the first and second variable delay circuits, for comparing samples of the first and second legs of the differential signal to identify a differential skew therebetween, for establishing delays of the first and second variable delay circuits, and for substantially correcting for the effects of the differential skew.
A pin electronics circuit for an automatic test system for testing a device under test (DUT), comprising:
- at least one analog holding circuit connectable to the DUT for receiving first and second legs of a differential signal and for sampling said first and second legs at predetermined instants of time respectively defined by first and second timing signals;
- and
- at least one ADC having an input coupled to the at least one analog holding circuit for converting analog signals to digital values, and an output connectable to at least one memory for storing said digital values,
- wherein the first and second timing signals are each variable for sampling said first and second legs of the differential signal at different instants of time, and
- wherein digital values stored in the memory are accessible by a processor for determining a differential skew between the first and second legs of the differential signal.
In an automatic test system, a method of deskewing first and second legs of a repetitive, differential signal received by the automatic test system from a DUT (device under test), comprising:
- undersampling each of the first and second legs of the differential signal to generate first and second collections of sampled data;
- analyzing the first and second collections of sampled data to identify a first feature within the first collection of sampled data and a second feature within the second collection of sampled data that corresponds in time to the first feature;
- and
- determining the skew between the first and second legs of the differential signal as the time difference between the first and second features.
A method of manufacturing integrated circuits, comprising:
- connecting an automatic test system to nodes of an integrated circuit, the automatic test system including a plurality of electronic circuits for receiving differential signals produced by the integrated circuit;
- undersampling, by at least one of the plurality of electronic circuits, first and second legs of a differential signal produced by the integrated circuit, to generate first and second collections of sampled data;
- analyzing the first and second collections of sampled data to determine a differential skew between the first and second legs of the differential signal;
- correcting for the differential skew in measurements of the differential signal;
- and
- determining a testing status of the integrated circuit in response to a corrected measurement of the differential signal.
Dependencies are inferred from the claim text.