Browsing by Author "Chen, Yuan"

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A 2.4-Gsample/s DVFS FFT processor for MIMO OFDM communication systems
(2008-05-01)
Chen, Yuan
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Lin, Yu-Wei
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Tsao, Yu-Chi
;
Lee, Chen-Yi
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電子工程學系及電子研究所
This paper presents a new dynamic voltage and frequency scaling (DVFS) FFT processor for MIMO OFDM applications. By the proposed multimode multipath-delay-feedback (MMDF) architecture, our FFT processor can process 1-8-stream 256-point FFTs or a high-speed 256-point FFT in two processing domains at minimum clock frequency for DVFS operations. A parallelized radix-2(4) FFT algorithm is also employed to save the power consumption and hardware cost of complex multipliers. Furthermore, a novel open-loop voltage detection and scaling (OLVDS) mechanism is proposed for fast and robust voltage management. With these schemes, the proposed FFT processor can operate at adequate voltage/frequency under different configurations to support the power-aware feature. A test chip of the proposed FITT processor has been fabricated using UMC 90 nm single-poly nine-metal CMOS process with a core area of 1.88 x 1.88 mm(2). The SQNR performance of this FFT chip is over 35.8 dB for QPSK/16-QAM modulation. Power dissipation of 2.4 Gsample/s 256-point FFT computations is about 119.7 mW at 0.85 V. Depending on the operation mode, power can be saved by 18%-43% with voltage scaling in TT corner.
A Generalized Mixed-Radix Algorithm for Memory-Based FFT Processors
(2010-01-01)
Hsiao, Chen-Fong
;
Chen, Yuan
;
Lee, Chen-Yi
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this brief, a generalized mixed-radix (GMR) algorithm is proposed for memory-based fast Fourier transform (FFT) processors to support prime-sized and traditional 2(n)-point FFTs simultaneously. It transforms the index to a multidimensional vector for efficient computation. By controlling the index vector to satisfy the "vector reverse" behavior, the GMR algorithm can support not only in-place policy for both computation and I/O data for continuous data flow to minimize the memory size but also multibank memory structures to increase the maximum throughput without memory conflict. Finally, a low-complexity implementation of an index vector generator is also proposed for our algorithm.
An indexed-scaling pipelined FFT processor for OFDM-based WPAN applications
(2008-02-01)
Chen, Yuan
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Tsao, Yu-Chi
;
Lin, Yu-Wei
;
Lin, Chin-Hung
;
Lee, Chen-Yi
In this brief, a high-throughput and low-complexity fast Fourier transform (FFT) processor for wideband orthogonal frequency division multiplexing communication systems is presented. A new indexed-scaling method is proposed to reduce both the critical-path delay and hardware cost by employing shorter wordlength. Together with the mixed-radix multipath delay feedback structure, the proposed FFT processor can achieve very high throughput with low hardware cost. From analysis, it is shown that the proposed indexed-scaling method can save at least 11% memory utilizations compared to other state-of-the-art scaling algorithms. Also,,a-test chip of a 1.2 Gsample/s 2048-point FFT processor has been designed using UMC 90-nm 1P9M process with a core area of 0.97 mm(2). The signal-to-quantization-noise ratio (SQNR) performance of this test chip is over 32.7 dB to support 16-QAM modulation and the power consumption is about 117 mW at 300 MHz. Compared to the fixed-point FFT processors, about 26% area and 28% power can be saved under the same throughput and SQNR specifications.
MEMORY-BASED FFT/IFFT PROCESSOR AND DESIGN METHOD FOR GENERAL SIZED MEMORY-BASED FFT PROCESSOR
(2010-01-21)
LEE, Chen-Yi
;
Hsiao, Chen-Fong
;
Chen, Yuan
For a large size FFT computation, this invention decomposes it into several smaller sizes FFT by decomposition equation and then transform the original index from one dimension into multi-dimension vector. By controlling the index vector, this invention could distribute the input data into different memory banks such that both the in-place policy for computation and the multi-bank memory for high-radix structure could be supported simultaneously without memory conflict. Besides, in order to keep memory conflict-free when the in-place policy is also adopted for I/O data, this invention reverses the decompose order of FFT to satisfy the vector reverse behavior. This invention can minimize the area and reduce the necessary clock rate effectively for general sized memory-based FFT processor design.