Block symmetrization in a field programmable gate array
View Patent ↗An FPGA architecture has top, middle and low levels. The top level is an array of B16×16 tiles enclosed by I/O blocks. The routing resources in the middle level are expressway routing channels including interconnect conductors. At the lowest level, there are block connect routing channels, local mesh routing channels, and direct connect interconnect conductors to connect the logic elements to further routing resources. Each B1 block includes four clusters of devices. Each of the clusters includes first and second LUT3s, a LUT2, and a DFF. Each of the LUT3s have three inputs and one output. Each of the LUT2s have two inputs and one output. Each DFF has a data input and a data output. In each of the clusters the outputs of the LUT3s are multiplexed to the input of DFF, and symmetrized with the output of the DFF to form two outputs of each of the clusters.
1. A hierarchical interconnect architecture for a field programmable gate array integrated circuit including a plurality of logic function blocks, the architecture including:
a third level including:
a plurality of third groups of functional logic blocks at the third level, wherein:
each third group spans a third length and a third width, and
a set of third routing resources that includes:
a plurality of freeway routing channels associated with each third group of functional logic blocks, each freeway routing channel associated with one of the third groups including a plurality of interconnect conductors configured to make programmable connections to functional logic blocks in other ones of the third groups; and
a second level including:
a plurality of second groups of functional logic blocks at the second level, wherein:
each second group spanning a second length and a second width, and
the number of functional logic blocks in the third groups is greater than the number of functional logic blocks in the second groups,
a set of second routing resources that includes:
a plurality of expressway routing channels including a plurality of interconnect conductors configured to make programmable connections between different ones of the functional logic blocks in the second group and to interconnect conductors in the set of third routing resources; and
a first level including:
a plurality of first groups of functional logic blocks at the first level, wherein:
each first group spans a first length and a first width,
the number of functional logic blocks in the second groups is greater than the number of functional logic blocks in the first groups,
each of the plurality of groups of functional blocks comprises a plurality of clusters, each cluster comprising at least one LUT and at least one DFF; and
a set of first routing resources;
a block connect routing channel including a plurality of interconnect conductors configured to make programmable connections between different ones of the functional logic blocks in the second group and to interconnect conductors in the set of second routing resources;
a local mesh routing channel including a plurality of interconnect conductors configured to make programmable connections between adjacent ones of the functional logic blocks in a single one of the first groups of the functional logic blocks;
a direct connect routing channel including a plurality of interconnect conductors configured to make programmable connections between selected elements of adjacent ones of the functional logic blocks in a single one of the first groups of the functional logic blocks.
2. The hierarchical interconnect architecture of claim 1 wherein:
programmable connections are made using reprogrammable elements.
3. The hierarchical interconnect architecture of claim 2 wherein:
the reprogrammable elements are SRAM switches.
4. The hierarchical interconnect architecture of claim 2 wherein:
the programmable connections between ones of the third group of functional logic blocks are made in a plurality of first programmable matrices of reprogrammable switches.
5. The hierarchical interconnect architecture of claim 1 wherein:
the interconnect conductors in the plurality of freeway routing channels have a length substantially equal to one of the third length and the third width.
6. The hierarchical interconnect architecture of claim 1 wherein:
programmable connections between different ones of the functional logic blocks in the second group and to interconnect conductors in the set of third routing resources are made in a plurality of second programmable matrices of reprogrammable switches.
7. The hierarchical interconnect architecture of claim 1 wherein:
programmable connections between different ones of the functional logic blocks in the second group and to interconnect conductors in the set of second routing resources are made in a plurality of third programmable matrices of reprogrammable switches.
8. The hierarchical interconnect architecture of claim 1 wherein:
each cluster comprises:
a plurality of three input LUTs, each having three inputs and an output;
a two input LUT; and
a DFF having an input and an output.
9. The hierarchical interconnect architecture of claim 8 wherein:
in each cluster:
the output of a first three input LUT is programmably coupled via a first programmable switch to the input of the DFF, and
the output of a second three input LUT is programmably coupled via a second programmable switch to the input of the DFF.
10. The hierarchical interconnect architecture of claim 9 wherein:
each cluster further comprises:
a first inverter having an output and an input programmably coupled to the output of the first three input LUT via a third programmable switch; and
a second inverter having an output and an input programmably coupled to the output of the second three input LUT via a fourth programmable switch.
11. The hierarchical interconnect architecture of claim 10 wherein:
in each cluster:
the output of the DFF is programmably coupled via a fifth programmable switch to the input of the first inverter; and
the output of the DFF is programmably coupled via a sixth programmable switch to the input of the second inverter.
12. The hierarchical interconnect architecture of claim 10 wherein:
each cluster is associated with:
a first output switch box having an input programmably coupled to the output of the first inverter via a seventh programmable switch and coupled to the output of the second inverter via a eighth programmable switch; and
a second output switch box having an input programmably coupled to the output of the first inverter via a ninth programmable switch and coupled to the output of the second inverter via a tenth programmable switch.