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In this paper, we present a 4-parallel fast Fourier transform (FFT) processor for a multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra wideband (UWB) system. The proposed FFT processor utilizes radix-2 4 structure so as to significantly enhance the hardware complexity by reducing the numbers of multipliers and adders. The hardware efficient 4-parellel 128-point FFT processor employing the decimation-in-frequency (DIF) and the singlepath delay feedback (SDF) algorithms can support throughput rates of up to 1 Gsample/s. The proposed FFT processor is implemented and tested by adopting the 0.18 m μ CMOS technology with a supply voltage of 1.8 V. Index Terms -FFT, canonic signed digit multiplier (CSDM), MB-OFDM, UWB.

In this paper, we present a fast Fourier transform (FFT) processor with four parallel data paths for multiband orthogonal frequency‐division multiplexing ultra‐wideband systems. The proposed 128‐point FFT processor employs both a modified radix‐24 algorithm and a radix‐23 algorithm to significantly reduce the numbers of complex constant multipliers and complex booth multipliers. It also employs substructure‐sharing multiplication units instead of constant multipliers to efficiently conduct multiplication operations with only addition and shift operations. The proposed FFT processor is implemented and tested using 0.18 µm CMOS technology with a supply voltage of 1.8 V. The hardware‐ efficient 128‐point FFT processor with four data streams can support a data processing rate of up to 1 Gsample/s while consuming 112 mW. The implementation results show that the proposed 128‐point mixed‐radix FFT architecture significantly reduces the hardware cost and power consumption in comparison to existing 128‐point FFT architectures.

Pt collector and LiCoO2 cathode films were deposited onto trench-SiO2/Si substrates by liquid-delivery metalorganic chemical vapor deposition (LDMOCVD). The 100-nm-thick Pt thin films deposited at 350 °C showed the lowest resistivity and roughness and step-coverage of 57% in trench structure (aspect ratio-1). The LiCoO2 cathode films (step-coverage=51%) deposited onto a Pt collector showed an increase of approximately two and half times the discharge capacity compared with those of planar-cathode films. The LDMOCVD process is suitable to improve the discharge capacity of LiCoO2 cathode films using a trench structure in lithium rechargeable batteries.