A New Architecture of Twiddle Factor Generator for Radix-2 1024-Point FFT

A new ROMless twiddle factor generator for radix-2 1024-point FFT is proposed.It consists of several simple logic units and each of them synthesizes some data,which will be used to compose the twiddle factors.The power analysis with Synopsys Power Compiler shows that it consumes about 2mW with TSMC 0.25μm CMOS process at 50MHz.This twiddle factor generator is designed for the low power applications,especially for the mobile communications and other portable devices...

Design and implementation of FFT/IFFT in IEEE 802.16d OFDM system

The IEEE 802. 16 standard specifies the air interface of wireless metropolitan area network （WMAN）, and aims to provide wireless broadband access for integrated voice and video services. This paper presents the efficient design and implementation of fast Frouier transform （FFT） and inverse fast Frouier transform （IFFT） for the application in IEEE 802. 16d orthogoual frequency division multiplexing （OFDM） system. In this design, a novel pipeline structure for the branch of butterfly unit （BU） is proposed, which can improve the processing symbol rate by adding the number of branch flexibly. The symmetrical ping-pang structure of random access memory （RAM） is performed to increase the system throughput. Simulation results reveal that only with 1 branch of BU, the proposed FFF/IFFT design can almost achieve the maximum bandwidth requirement of IEEE 802. 16d OFDM system. And this design has been verified by FPGA and successfully implemented in the prototype of WiMAX transceiver.

Conductive metallic filaments dominate in hybrid perovskite-based memory devices

Organic-inorganic hybrid perovskites (OHPs) are well-known as light-absorbing materials in solar cells and have recently attracted considerable attention for the applications in resistive switching memory. Previous studies have shown that ions can migrate to form a conductive channel in perovskites under an external voltage. However, the exact resistance mechanism for Ag or halogens which dominate the resistive behavior is still controversial. Here, we demonstrate a resistive switching memory device based on Ag/FA0.83MA0.17Pb(I0.82Br0.18)3/fluorine doped tin oxide (FTO). The migration of Ag cations and halide anions is demonstrated by energy dispersive X-ray spectroscopy (EDS) after the SET process (positive voltage on Ag). By comparing the I-V behavior of the Au-based devices, it is clear that the conductive channel formed by Ag is the main factor of the switching characteristics for Ag-based devices. Meanwhile, by controlling the appropriate SET voltage, two kinds of resistance characteristics of the analog switch and threshold switch can be realized in the Ag-based device. As a result, it may be possible to implement both data storage and neuromorphic computing in a single device.

Ultraviolet mem-sensors： Flexible anisotropic composites featuring giant photocurrent enhancement

By using two separate components, mem-sensing devices can be fabricated combining the sensitivity of a transducer with non-volatile memory. Here, we discuss how a mem-sensor can be fabricated using a single material with built- in sensing andmemory capabilities, based on ZnO microwires （MWs） embedded in a photocurable resin and processed from liquid by vertically aligning the MWs across the polymeric matrix using dielectrophoresis. This results in an ultraviolet （UV） photodetector, a device telecommunication, health, and defense, that is widely applied in fields such as and has so far implemented using bulk inorganic semiconductors. However, inorganic detectors suffer from very high production costs, brittleness, huge equipment requirements, and low responsivity. Here, we propose for the first time aneasy processable, reproducible, and low- cost hybrid UV mem-sensor. Composites with aligned ZnO MWs produce giant photocurrentscompared to the same composites with randomly distributed MWs. In particular, we efficiently exploit a mere-response where the photocurrent carries memory of the last electronic state experienced by the device when under testing. Furthermore, we demonstrate the non-equivalence of different wave profiles used during thedielectrophoresis： a pulsed wave is able to induce order in both the axis and the orientation of the MWs, whereas a sine wave only affects the orientation.