Dedicated logic cells employing configurable logic and dedicated logic functions
View Patent ↗A dedicated logic cell in a programmable logic structure is described that comprises the following primary components: a configurable logic function or look-up table (LL), a dedicated logic function (DL), a sequential logic function (LS), and a control logic function (LC). In this illustration, the dedicated logic cell comprises two configurable logic functions, two sequential logic functions, a dedicate logic function, and a control logic function. In a first embodiment, the dedicated logic cell is constructed with a combination of configurable logic functions that are coupled to a dedicated logic function in order to perform a four 2-input function, an AND function, an OR function, or an XOR function. In a second embodiment, the dedicated logic cell is constructed with a combination of configurable logic functions that are coupled to a dedicated logic function in order to perform a four 2-to-1 multiplexer function. In a third embodiment, the dedicated logic cell is constructed with a plurality of configurable logic functions that operate as a two 6-input function with separate inputs. In a fourth embodiment, the dedicated logic cell is constructed with a combination of a configurable logic function with sequential logic functions that operate as a loadable, resettable, clearable shift register. In a fifth embodiment, the dedicated logic cell is constructed with a combination of configurable logic functions, a dedicated logic function, and sequential logic functions that operate as an accumulator.
1. A dedicated logic cell, comprising:
in a first logic and routing cell, comprising
a first configurable logic function (LL) having at least one input and at least one output;
a dedicated logic function (LD) having at least one input and at least one output, the at least one input of the dedicated logic function coupled to the at least one output of the first configurable logic function; and
a first sequential logic function (LS) having at least one input and at least one output, the least one input of the first sequential logic function coupled to the at least one output of the dedicated logic function;
wherein the configurable logic function (LL) structure comprises:
a first look-up table having a plurality of inputs for receiving a set of inputs and at least one output;
a second look-up table having a plurality of inputs for receiving the set of inputs and at least one output;
a third look-up table having at least one input and at least one output;
a fourth-look-up table having at least one input and at least one output; and
a 4-to-1 multiplexer having a first input coupled to the at least one output of the first look-up table, a second input coupled to the least one output of the second look-up table, a third input coupled to the least one output of the third look-up table, a fourth input coupled to the at lest one output of the fourth look-up table, a first select pin or a fifth input pin, a second select pin or a sixth input pin, and an output.
2. The dedicated logic cell of claim 1 , further comprising:
in a second logic and routing cell, coupled to the first logic and routing cell, comprising:
a second configurable logic function (LL) having at least one input and at least one output;
a control logic function (LC) having at least one input and at least one output, the at least one input of the control logic function coupled to the at least one output of the second configurable logic function; and
a second sequential logic function (LS) having at least one input and at least one output, the least one input of the second sequential logic function coupled to the at least one output of the control logic function.
3. The dedicated logic cell of claim 1 , wherein the 4-to-1 multiplexer comprises a first select pin and a second select pin, thereby configuring the configurable logic function structure to a 6-input look-up table.
4. The dedicated logic cell of claim 1 , wherein the 4-to-1 multiplexer comprises a fifth input pin and a sixth input, thereby configuring the configurable logic function structure to a 4-to-1 multiplexer.
5. The dedicated logic cell of claim 1 , wherein each of the first, second, third, and fourth look-up table is a four-input function.
6. The dedicated logic cell of claim 1 , wherein the dedicated logic function structure comprises:
a first multiplexer having a first input for receiving a first operation, a second input for receiving a second operation, a select input line, and an output; and
a second multiplexer having one or more inputs for receiving one or more operations, a first select input line, a second select input line, and an output coupled to the first input of the first multiplexer; and
a third multiplexer having one or more inputs for receiving one or more operations, a first select input line, a second select input line, and an output coupled to the second input of the first multiplexer.
7. The dedicated logic cell of claim 6 , further comprising a first select signal generated to the select input line in the first multiplexer, a second select signal generated to the first select input line in the second multiplexer and the first select input line in the third multiplexer, and a third select signal generated to the second input line in the second multiplexer and the second select input line in the third multiplexer.
8. The dedicated logic cell of claim 6 , wherein the first, second, third select signals are set during configuration.
9. The dedicated logic cell of claim 6 , wherein the first, second, third select signals are dynamically adjustable during operation.
10. The dedicated logic cell of claim 6 , wherein the one or more operations comprise an arithmetic operation, an add operation, a subtraction operation, an addsub operation with dynamic control, a multiply operation, a divide operation, an accumulator operation a five-input look-up table, an eight-input function, and a six-input look-up table.
11. The dedicated logic cell of claim 6 , wherein the one or more operations comprise a shift operation, a two-input look-up table, and a 6-input operation.
12. The dedicated logic cell of claim 6 , wherein the dedicated logic cell operates as an arithmetic logic unit.