Pipelined Fast Fourier Transform Processor Research Articles

Area-Efficient Pipelined FFT Processor for Zero-Padded Signals

This paper proposes an area-efficient fast Fourier transform (FFT) processor for zero-padded signals based on the radix-2 2 and the radix-2 3 single-path delay feedback pipeline architectures. The delay elements for aligning the data in the pipeline stage are one of the most complex units and that of stage 1 is the biggest. By exploiting the fact that the input data sequence is zero-padded and that the twiddle factor multiplication in stage 1 is trivial, the proposed FFT processor can dramatically reduce the required number of delay elements. Moreover, the 256-point FFT processors were designed using hardware description language (HDL) and were synthesized to gate-level circuits using a standard cell library for 65 nm CMOS process. The proposed architecture results in a logic gate count of 40,396, which can be efficient and suitable for zero-padded FFT processors.

Design and Implementation of High-Speed Variable Point Pipelined FFT Processor for OFDM System using Verilog

Objectives: For Orthogonal Frequency Division Multiplexing (OFDM), Fast Fourier Transform (FFT) processoris required. So, in this work, a variable point Pipelined FFT processor is designed by utilizing Verilog language. Further transmitter and receiver blocks are designed to form OFDM system. Methods: Speed enhancement is the key area which is been looked into this project work. Pipelined Architecture that is going to be implemented is RS2DF (Radix-2 Single path Delay Feedback). Standard FPGA Flow is adapted to implement this project i.e., right from specification to bit file generation. Simulations and Synthesis will be done using Questasim and Xilinx ISE. Verilog Simulations will be compared with in-built MATLAB FFT Core. MATLAB is used for reference and verification. Findings: This Project clarified the usage of FFT IP and OFDM in Xilinx ISE focusing on a specific family of FPGA. The execution of the proposed algorithm ought to perform superior to anything the base algorithm with the all-out basic way getting additionally advanced along these lines expanding the speed of activity. maximum operation frequency achieved was 236.189MHz but in base paper maximum operation frequency was 30Mhz. The systems utilized are Interna1 and externa1 Pipe1ining of modules and Distributed LUT based idea, the target of the above methods is to lessen the basic way deferral and increment the general speed of activity of structure, the disadvantage is the increments in area and output latency. Area is not of a much issue as present day days FPGAs has immense measure of assets. Output 1atency should be taken consideration with additional rationale at whatever point FFT is coordinated with other system modules. Application: The project depicts technique for streamlining timing basic ways of FFT to work at higher-speeds, to be utilized as a feature of LTE Protoca1 or any wire1ess protoco1 such as WLAN and LDACS. Keywords: Fast Fourier Transform (FFT), Hardware Description Language (HDL), Orthogonal Frequency Division Multiplexing (OFDM), Pipeline, Verilog

A Pipelined FFT Processor Using an Optimal Hybrid Rotation Scheme for Complex Multiplication: Design, FPGA Implementation and Analysis

The fast Fourier transform (FFT) is the most prevalent algorithm for the spectral analysis of acoustic emission signals acquired at ultra-high sampling rates to monitor the condition of rotary machines. The complexity and cost of the associated hardware limit the use of FFT in real-time applications. In this paper, an efficient hardware architecture for FFT implementation is proposed based on the radix-2 decimation in frequency algorithm (R2DIF) and a feedback pipelined technique (FB) that allows effective sharing of storage between the input and output data at each stage of the FFT process via shift registers. The proposed design uses an optimal hybrid rotation scheme by combining the modified coordinate rotation digital computer (m-CORDIC) algorithm and a binary encoding technique based on canonical signed digit (CSD) for replacing the complex multipliers in FFT. The m-CORDIC algorithm, with an adaptive iterative monitoring process, improves the convergence of computation, whereas the CSD algorithm optimizes the multiplication of constants using a simple shift-add method. Therefore, the proposed design does not require the large memory typically entailed by existing designs to carry out twiddle factor multiplication in large-point FFT implementations, thereby reducing its area on the chip. Moreover, the proposed pipelined FFT processor uses only distributed logic resources and does not require expensive dedicated functional blocks. Experimental results show that the proposed design outperforms existing state-of-the-art approaches in speed by about 49% and in resource utilization by around 51%, while delivering the same accuracy and utilizing less chip area.

Design and Implementation of Fast Fourier Transform (FFT) using VHDL Code

The Discrete Fourier Transform (DFT) can be implemented very fast using Fast Fourier Transform (FFT). It is one of the finest operation in the area of digital signal and image processing. FFT is a luxurious operation in terms of MAC. To achieve FFT calculation with a many points and with maximum number of samples the MACs requirement could not be matched by efficient hardware’s like DSP. A parallel and pipelined Fast Fourier Transform (FFT) processor for use in the Orthogonal Frequency division Multiplexer (OFDM) and WLAN, unlike being stored in the traditional ROM. The twiddle factors in our pipelined FFT processor can be accessed directly. In this paper, we present the implementation of fast algorithms for the DFT for evaluating their performance. The performance of this algorithm by implementing them on the Xillinx 9.2i Spartan 3E FPGAs by developing our own FFT processor architecture.

Signal-to-noise Ratio Study on Pipelined Fast Fourier Transform Processor

Fast Fourier transform (FFT) processor is a prevailing tool in converting signal in time domain to frequency domain. This paper provides signal-to-noise ratio (SNR) study on 16-point pipelined FFT processor implemented on field-programable gate array (FPGA). This processor can be used in vast digital signal applications such as wireless sensor network, digital video broadcasting and many more. These applications require accuracy in their data communication part, that is why SNR is an important analysis. SNR is a measure of signal strength relative to noise. The measurement is usually in decibles (dB). Previously, SNR studies have been carried out in software simulation, for example in Matlab. However, in this paper, pipelined FFT and SNR modules are developed in hardware form. SNR module is designed in Modelsim using Verilog code before implemented on FPGA board. The SNR module is connected directly to the output of the pipelined FFT module. Three different pipelined FFT with different architectures were studied. The result shows that SNR for radix-8 and R4SDC FFT architecture design are above 40dB, which represent a very excellent signal. SNR module on the FPGA and the SNR results of different pipelined FFT architecture can be consider as the novelty of this paper.

Design of Processing Element (PE3) for Implementing Pipeline FFT Processor

Multiplexing is a method by which multiple analog message signals or digital data streams are combined into one signal over a shared medium. In communication, different multiplexing schemes are used. To achieve higher data rates, Orthogonal Frequency Division Multiplexing (OFDM) is used due to its high spectral efficiency. OFDM became a serious alternative for modern digital signal processing methods based on the Fast Fourier Transform (FFT).The problems with Orthogonal subcarriers can be addressed with FFT in communication applications. An 8-bit processing element (PE3), used in the execution of a pipeline FFT processoris designed and presented in this paper. Simulations are carried out using Mentor Graphics tools in 130nm technology.

A Normal I/O Order Radix-2 FFT Architecture to Process Twin Data Streams for MIMO

Nowadays, many applications require simultaneous computation of multiple independent fast Fourier transform (FFT) operations with their outputs in natural order. Therefore, this brief presents a novel pipelined FFT processor for the FFT computation of two independent data streams. The proposed architecture is based on the multipath delay commutator FFT architecture. It has an $N/2$ -point decimation in time FFT and an $N/2$ -point decimation in frequency FFT to process the odd and even samples of two data streams separately. The main feature of the architecture is that the bit reversal operation is performed by the architecture itself, so the outputs are generated in normal order without any dedicated bit reversal circuit. The bit reversal operation is performed by the shift registers in the FFT architecture by interleaving the data. Therefore, the proposed architecture requires a lower number of registers and has high throughput.

Area-Efficient 128- to 2048/1536-Point Pipeline FFT Processor for LTE and Mobile WiMAX Systems

Fast Fourier transform (FFT) is widely used in digital signal processing and telecommunications, particularly in orthogonal frequency division multiplexing systems, to overcome the problems associated with orthogonal subcarriers. This paper presents a novel 128/256/512/1024/1536/2048-point single-path delay feedback (SDF) pipeline FFT processor for long-term evolution and mobile worldwide interoperability for microwave access systems. The proposed design employs a low-cost computation scheme to enable 1536-point FFT, which significantly reduces hardware costs as well as power consumption. In conjunction with the aforementioned 1536-point FFT computation scheme, the proposed design included an efficient three-stage SDF pipeline architecture on which to implement a radix-3 FFT. The new radix-3 SDF pipeline FFT processor simplifies its data flow and is easy to control, and the complexity of the resulting hardware is lower than that of existing structures. This paper also formulated a hardware-sharing mechanism to reduce the memory space requirements of the proposed 1536-point FFT computation scheme. The proposed design was implemented using 90 nm CMOS technology. Postlayout simulation results revealed a die area of approximately $1.44 \times 1.44~\mathrm{mm}^{2}$ with power consumption of only 9.3 mW at 40 MHz.

Constant twiddle factor multiplier sharing in multipath delay feedback parallel pipelined FFT processors

A new constant twiddle factor multiplier sharing method in parallel pipelined fast Fourier transform (FFT) processors based on a multi-path delay feedback architecture which consists of multiple single-path delay feedback datapaths is presented. The proposed method exploits constant twiddle factor multiplier relocation which moves a constant twiddle factor multiplier into a feedback path based on twiddle factor decomposition. By relocating a twiddle factor multiplier, the timing of twiddle factor multiplications is changed so that the multiplications with a twiddle factor are performed at different clock cycles in two datapaths, which makes it possible that the two datapaths share a multiplier operating with the twiddle factor. A reduction of 50% in the number of constant twiddle factor multipliers in the first two stages of a 128-point four-parallel pipelined FFT processor is achieved using the proposed method.

Design and Simulation of 256 bit 64-point FFT Using RADIX 4 Algorithm

A Parallel and pipelined Fast Fourier transform(FFT) processor for use in the orthogonal frequency division multiplexer .it is important to develop a high performance FFT processor to meet the requirements of the real time and low cost in many different systems. Un like being stored in the traditional ROM, the twiddle factors in our pipelined FFT processor can be accessed directly. here we simulated and synthesized the 256 bit 64 point FFT with radix 4 using VHDL coding and simulation and synthesis done by Modelsim ISE and Xilinx ISE design suite respectively.

Design and Simulation of FFT Processor Using Radix-4 Algorithm Using FPGA

A parallel and pipelined Fast Fourier Transform (FFT) processor for use in the Orthogonal Frequency division Multiplexer (OFDM) and WLAN, unlike being stored in the traditional ROM. The twiddle factors in our pipelined FFT processor can be accessed directly. A novel simple address mapping scheme and the modified radix 4 FFT also proposed. FPGA was majorly used to develop the ASIC IC’s to which was implemented. Here we simulated and synthesized the 256- point FFT with radix-4 using VHDL coding and 64 point FFT Hardware implementation we designed code using System C. Finally, the pipelined 256-point FFT processor can be completely implemented within 19.103ns.

High-Performance Low-Power FFT Cores

Recently, the power consumption of integrated circuits has been attracting increasing attention. Many techniques have been studied to improve the power efficiency of digital signal processing units such as fast Fourier transform (FFT) processors, which are popularly employed in both traditional research fields, such as satellite communications, and thriving consumer electronics, such as wireless communications. This paper presents solutions based on parallel architectures for high throughput and power efficient FFT cores. Different combinations of hybrid low-power techniques are exploited to reduce power consumption, such as multiplierless units which replace the complex multipliers in FFTs, low-power commutators based on an advanced interconnection, and parallel-pipelined architectures. A number of FFT cores are implemented and evaluated for their power/area performance. The results show that up to 38% and 55% power savings can be achieved by the proposed pipelined FFTs and parallel-pipelined FFTs respectively, compared to the conventional pipelined FFT processor architectures.

An Indexed-Scaling Pipelined FFT Processor for OFDM-Based WPAN Applications

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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . 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.

Long-Point FFT Processing Based on Twiddle Factor Table Reduction

In this paper, we present a new fast Fourier transform (FFT) algorithm to reduce the table size of twiddle factors required in pipelined FFT processing. The table size is large enough to occupy significant area and power consumption in long-point FFT processing. The proposed algorithm can reduce the table size to half, compared to the radix-22 algorithm, while retaining the simple structure. To verify the proposed algorithm, a 2048-point pipelined FFT processor is designed using a 0.18 μm CMOS process. By combining the proposed algorithm and the radix-22 algorithm, the table size is reduced to 34% and 51% compared to the radix-2 and radix-22 algorithms, respectively. The FFT processor occupies 1.28 mm2 and achieves a signal-to-quantization-noise ratio (SQNR) of more than 50 dB.

Balanced Binary-Tree Decomposition for Area-Efficient Pipelined FFT Processing

This paper presents an area-efficient algorithm for the pipelined processing of fast Fourier transform (FFT). The proposed algorithm is to decompose a discrete Fourier transform (DFT) into two balanced sub-DFTs in order to minimize the total number of twiddle factors to be stored into tables. The radix in the proposed decomposition is adaptively changed according to the remaining transform length to make the transform lengths of sub-DFTs resulting from the decomposition as close as possible. An 8192-point pipelined FFT processor designed for digital video broadcasting-terrestrial (DVB-T) systems saves 33% of general multipliers and 23% of the total size of twiddle factor tables compared to a conventional pipelined FFT processor based on the radix-22 algorithm. In addition to the decomposition, several implementation techniques are proposed to reduce area, such as a simple index generator of twiddle factor and add/subtract units combined with the two's complement operation

An efficient locally pipelined FFT processor

The fast Fourier transform (FFT) is a very important algorithm in digital signal processing. The locally pipelined (LPPL) architecture is an efficient structure for FFT processor designing in a real-time embedded system. Two basic building blocks, to the LPPL FFT processor, the butterfly in pipeline, and address generating, are discussed in this brief. Based on the feedback to butterfly-2, a novel approach for pipelined architecture, the radix-2 single-path deep delay feedback architecture is proposed. For length-N discrete Fourier transform computation, the dominant hardware requirements are minimal for complex multipliers log/sub 4/N-1 and adders 2log/sub 4/N. As an integral need of the LPPL FFT processor design, address generating and coefficient store-load structures are also presented.

Implementation of Orthogonal Frequency Division Multiplexing Modem Using Radix-N Pipeline Fast Fourier Transform (FFT) Processor

In this paper, a new Radix-N pipeline fast Fourier transform (FFT) processor for the implementation of IEEE 802.11a baseband orthogonal frequency division multiplexing (OFDM) modem for wireless local area network (WLAN) is proposed. The newly proposed scheme has a simple control structure and multiplication block is designed based on canonic signed digit (CSD) with N/4 twiddle factors, which enables both hardware complexity and power consumption to be reduced as about less 33% and 66% respectively than the conventional Radix-4 pipeline and Radix-2 pipeline structures. In order to verify the real time operation, the IEEE802.11a baseband OFDM test-bed with the newly proposed Radix-N pipeline FFT processor is implemented using field programmable gate array (FPGA) devices.