| dc.description.abstract | Discrete Multitone modulation (DMT) is the physical-layer transmission standard of Asymmetric Digital Subscriber Line (ADSL). It can achieve rate-adaptive high-speed transmission over twisted-pair copper lines in telephone carrier serving areas (CSA). But, one major disadvantage of the DMT scheme is its high computational/hardware complexity, especially for the IFFT/FFT operations that form the multitone processing kernels. In this thesis, we employ time-recursive FFT architecture to realize the IFFT module in DMT transmitter. To reduce the iteration number of the time-recursive IFFT, we reorder the input data. Hence, the iteration number is halved and the hardware complexity is reduced, too.
Furthermore, we employ Cordinate Rotation Digital Computer (CORDIC) to replace the multiplier-based rotator, which is the original kernel of the time-recursive IFFT. After reviewing some CORDIC-based rotators, we choose Extended Elementary-Angle Set CORDIC (EEAS-CORDIC) due to its high performance of speed. A new design flow is also developed to reduce the hardware complexity of the shifters in EEAS-CORDIC. By going through this flow, the gate count of all shifters is reduced 51%, and overall gate count of new CORDIC is saved 32%. Simultaneously, the speed and accuracy performance can also achieve the specification after combining the modified time-recursive IFFT and the new CORDIC. By the improvements of our work, the new IFFT module is more suitable for practical implementation. | en_US |