International Business Machines Corporation

Mark S Garvin

Nandor G Thoma

James W Davis

Jacquelin Babakanian

Yoav Medan

David M Wu

Robert M Swanson

Kim P Liew

Groups of DCVS (Differential Cascode Voltage Switch) circuits are interconnected by single-track data transfer connections. Each group contains one or more DCVS tree circuits, through which data signals propagate only on dual-track connections. In each group, at least one DCVS tree circuit is configured as an input boundary tree, and at least one tree circuit is configured as an output boundary tree. All data inputs externally applied to a group, are transferred only through input boundary trees of the group, and all data outputs transferred out of a group leave the group only through output boundary trees of the group. If a group has only a single tree, that tree serves as input and output boundary tree of the group. Each input boundary tree of each group has one or more associated primary shift register latch (SRL) circuits through which all external data inputs to that tree are transferred. Such external data inputs are received through the single-track connections mentioned above. The primary SRL circuits are also used to present predeterminable test data inputs to respective trees, and to collect primary test data outputs representing signals received through the single-track connections. In such usage, the SRL circuits are connected as a scannable shift register. Each output boundary tree has an exclusive-OR (XOR) circuit for indicating if the respective tree is in a legal or illegal state. The XOR circuits connect to secondary scannable SRL circuits for external presentation of illegal state indication. The primary test data outputs together with the externally presented illegal state indications form a basis for detecting and locating any faulty state in any group.

Fully testable DCVS circuits with single-track global wiring

A basic tree construction, from which differential cascode voltage switch (DCVS) circuits having variable logic personality can be formed, contains n (&gt;2) rows of differentially associated semiconductor device pairs spanned by n pairs of complementary input conductor leads, and a load circuit coupled to drain terminals of devices in the nth row. The nth row contains 2 device pairs and each other row contains 2.sup.i-1 device pairs (i=1, 2, . . . , n-1). Connections between source and drain terminals of devices in successive rows are predefined from the 1st to the n-1st row and variably definable between the n-1st and nth rows. Connections between input conductors and device gate terminals are predefined in each row other than the nth row, and variably definable in the nth row. Upon selectively defining a set of variable connections relative to the n-1st and nth rows the logic personality of the tree is selected to conform to any one of all possible functions of n variables. Logic function personalization is established in one embodiment by altering materials at discrete points in a space between n-1st and nth rows. In another embodiment, personalization is established by altering signals stored by latch devices in the space between the n-1st and nth rows which control gating device adjacently positioned to form conductive connections corresponding to those formed by altering materials in the first embodiment.

Programmable DCVS logic circuits

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Palm Beach, FL, United States of America

Mark S Garvin