Combined IFFT and FFT system

A system for determining discrete transforms as between time and frequency domains, comprising:

• a grid comprising adders and multipliers, the grid operable to perform in parallel an integer number P operations of a first transform function selected from one of either an IFFT or an FFT;
• and
• the integer number of P serially-operating pipelines, wherein each of the pipelines is coupled to the grid and is operable to perform serially over a number of cycles an integer number S operations of the first transform;
• wherein S and P are both greater than one;
• wherein in combination the grid and the serially-operating pipelines perform the first transform type as an S×P-point transform;
• wherein in a first instance at least a portion of the grid is operable to perform IFFT operations;
• wherein in a second instance at least a portion of the grid is operable to perform FFT operations;
• wherein in the first instance at least a portion of the integer number of P serially-operating pipelines is operable to perform, serially over a number of cycles, the integer number S of IFFT operations;
• and
• wherein in the second instance at least a portion of the integer number of P serially-operating pipelines is operable to perform, serially over a number of cycles, the integer number S of FFT operations;
• and
• wherein each of the integer number of P serially-operating pipelines comprises:
• an integer number X of butterfly circuits;
• and
• the integer number X of collection circuits, each coupled to a respective one of the integer number X of butterfly circuits by coupling an output from the respective butterfly circuit to the respective collection circuit and by coupling an output from the respective collection circuit to the respective butterfly circuit;
• and
• further comprising circuitry for swapping, in response to a transition between the first instance and the second instance, a Real coefficient with an Imaginary coefficient for each sample input to the system and for each transformed sample output from the system.

A method of determining discrete transforms as between time and frequency domains, comprising:

• operating, in a first instance, at least a portion of a grid comprising adders and multipliers, to perform in parallel an integer number P operations of a first transform function selected from one of either an IFFT or an FFT;
• and
• operating in the first instance, at least a portion of the integer number of P serially-operating pipelines wherein each of the pipelines is coupled to the grid, to perform serially over a number of cycles an integer number S operations of the first transform;
• wherein S and P are both greater than one;
• wherein in combination the grid and the serially-operating pipelines perform the first transform type as an S×P-point transform.
• wherein in the first instance the operating step comprises operating at least a portion of the grid is operable to perform IFFT operations;
• and
• further comprising:
• operating, in a second instance, at least a portion of the grid to perform in parallel a number of FFT operations;
• and
• operating in the second instance, at least a portion of the integer number of P serially-operating pipelines to perform serially over a number of cycles an integer number S of FFT operations.