Crossbar structure with mechanism for generating constant outputs

Abstract

Embodiments provide crossbar structures, and reconfigurable circuits that contain crossbar structures, that include n inputs and an output, where n is an integer, chains of transistors coupled to the n inputs and the output, a plurality of control signal elements—each coupled to one or more transistors of the plurality of chains of transistors to selectively couple said n inputs to the output—and an additional chain of transistors coupled to at least some of the plurality of control signal elements and the output to selectively couple a constant output voltage to the output. Other embodiments may be disclosed and claimed.

1 . A crossbar structure comprising:
 n inputs and an output, where n is an integer;   a plurality of chains of transistors coupled to the n inputs and to the output;   a plurality of control signal elements, each coupled to one or more transistors of the plurality of chains of transistors to selectively couple said n inputs to the output; and   an additional chain of transistors coupled to at least some of the plurality of control signal elements and to the output to selectively couple a constant output voltage to the output.   
     
     
         2 . The crossbar structure of  claim 1  wherein the additional chain of transistors is configured to be coupled to a voltage source. 
     
     
         3 . The crossbar structure of  claim 1  wherein the additional chain of transistors is configured to selectively couple the constant output voltage to the output when the plurality of control signal elements are set to decouple all inputs from the output. 
     
     
         4 . The crossbar structure of  claim 1  wherein each of the plurality of chains of transistors is constituted with pass transistors, and the additional chain is constituted with other transistors. 
     
     
         5 . The crossbar structure of  claim 4  wherein the plurality of chains of pass transistors each includes at least a first pass transistor and a second pass transistor, wherein the plurality of control signal elements comprise a set of first-order control signal elements coupled to each of the first pass transistors and a set of second-order control signal elements each coupled to at least one of the second pass transistors. 
     
     
         6 . The crossbar structure of  claim 5  wherein the plurality of control signal elements are each coupled to less than all of the chains of transistors. 
     
     
         7 . The crossbar structure of  claim 5  further comprising a set of additional pass transistors each coupled between the output and different ones of the second pass transistors, wherein the plurality of control elements further comprises a third-order control element coupled to the additional pass transistors, and wherein the set of second-order control signal elements are each coupled to more than one of the second pass transistors. 
     
     
         8 . The crossbar structure of  claim 5  further comprising an output wire coupled between each of the chains of pass transistors and the output, and an isolation transistor coupled to the output wire to isolate a first subset of the plurality of pass transistors from a second plurality of the pass transistors when the isolation transistor is disabled by another control signal. 
     
     
         9 . The crossbar structure of  claim 5  further comprising a common output wire coupled to the output and a tri-state inverter coupled to the output wire and to subset of the plurality of pass transistors to selectively couple the subset of the plurality of pass transistors to the output wire. 
     
     
         10 . The crossbar structure of  claim 1  wherein the plurality of control signal elements each comprise a memory cell. 
     
     
         11 . A reconfigurable circuit comprising:
 a plurality of crossbar devices coupled to one another, at least one of the crossbar devices having:   n inputs and an output, where n is an integer;   a plurality of chains of transistors coupled to the n inputs and to the output;   a plurality of control signal elements, each coupled to one or more transistors of the plurality of chains of transistors to selectively couple said n inputs to the output; and   an additional chain of transistors coupled to at least some of the plurality of control signal elements and the output to selectively couple a constant output voltage to the output.   
     
     
         12 . The reconfigurable circuit of  claim 11  wherein the additional chain of transistors is configured to be coupled to a voltage source. 
     
     
         13 . The reconfigurable circuit of  claim 11  wherein the additional chain of transistors is configured to selectively couple the constant output voltage to the output when the plurality of control signal elements are set to decouple all inputs from the output. 
     
     
         14 . The reconfigurable circuit of  claim 11  wherein each of the plurality of chains of transistors is constituted with pass transistors, and the additional chain is constituted with other transistors. 
     
     
         15 . The reconfigurable circuit of  claim 14  wherein the plurality of chains of pass transistors each includes at least a first pass transistor and a second pass transistor, wherein the plurality of control signal elements comprise a set of first-order control signal elements coupled to each of the first pass transistors and a set of second-order control signal elements each coupled to at least one of the second pass transistors. 
     
     
         16 . The reconfigurable circuit of  claim 15  wherein the plurality of control signal elements are each coupled to less than all of the chains of transistors. 
     
     
         17 . The reconfigurable circuit of  claim 15  further comprising a set of additional pass transistors each coupled between the output and different ones of the second pass transistors, wherein the plurality of control elements further comprises a third-order control element coupled to the additional pass transistors, and wherein the set of second-order control signal elements are each coupled to more than one of the second pass transistors. 
     
     
         18 . The reconfigurable circuit of  claim 15  further comprising an output wire coupled between each of the chains of pass transistors and the output, and an isolation transistor coupled to the output wire to isolate a first subset of the plurality of pass transistors from a second plurality of the pass transistors when the isolation transistor is disabled by another control signal. 
     
     
         19 . The reconfigurable circuit of  claim 11  wherein the constant output voltage is either Vdd or ground. 
     
     
         20 . The reconfigurable circuit of  claim 11  wherein the plurality of control signal elements each comprise a memory cell. 
     
     
         21 - 26 . (canceled)