CORDIC Based Array Architecture for Affine Transformation of Images

In this paper a multiplierless array architecture of Affine transformation is proposed. The array architecture utilizes CoOrdinate Rotation DIgital Computer (CORDIC) arithmetic unit as the basic Processing Element (PE). To construct the architecture two types of CORDIC units viz. the circular and linear are used. The architecture is flexible and can be configured according to the specification of the user. Due to its multiplierless organization the array architecture is expected to consume less silicon area and power compared to that of the multiplier-based designs

A VLSI Array Architecture for Realization of DFT, DHT, DCT and DST

A unified array architecture is described for computation of DFT, DHT, DCT and DST using a modified CORDIC (CoOrdinate Rotation DIgital Computer) arithmetic unit as the basic Processing Element (PE). All these four transforms can be computed by simple rearrangement of input samples. Compared to five other existing architectures, this one has the advantage in speed in terms of latency and throughput. Moreover, the simple local neighborhood interprocessor connections make it convenient for VLSI implementation. The architecture can be extended to compute transformation of longer length by judicially cascading the modules of shorter transformation length which will be suitable for Wafer Scale Integration (WSI). CORDIC is designed using Transmission Gate Logic (TGL) on sea of gates semicustom environment. Simulation results show that this architecture may be a suitable candidate for low power/low voltage applications

New virtually scaling free adaptive CORDIC rotator

In this article we propose a novel CORDIC rotator algorithm that eliminates the problems of scale factor compensation and limited range of convergence associated with the classical CORDIC algorithm. In our scheme, depending on the target angle or the initial coordinate of the vector, a scaling by 1 or 1/?2 is needed that can be realised with minimal hardware. The proposed CORDIC rotator adaptively selects appropriate iteration steps and converges to the final result by executing 50% less number of iterations on an average compared to that required for the classical CORDIC. Unlike classical CORDIC, the final value of the scale factor is completely independent of number of executed iterations. Based on the proposed algorithm, a 16-bit pipelined CORDIC rotator implementation has been described. The silicon area of the fabricated pipelined CORDIC rotator core is 2.73 mm2. This is equivalent to 38 k inverter gates in IHP in-house 0.25 ?m BiCMOS technology. The average dynamic power consumption of the fabricated CORDIC rotator is 17 mW @ 2.5 V supply and 20Msps throughput. Currently, this CORDIC rotator is used as a part of the baseband processor for a project that aims to design a single-chip wireless modem compliant with IEEE 802.11a and Hiperlan/2

A VLSI Array Architecture for Hough Transform

In this article, an asynchronous array architecture for straight line Hough Transform (HT) is proposed using a scaling free modified CORDIC (Co-Ordinate Rotation Digital Computer) unit as a basic Processing Element (PE). It exhibits four-fold angle parallelism by dividing the Hough space into four subspaces to reduce the computation burden to 25 % of the conventional requirements. A distributed accumulator arrangement scheme is adopted to ensure conflict free voting operation. The architecture is then extended to compute circular and elliptic HT given their centers and orientations. Compared to some other existing architectures, this one exhibits higher computation speed

A 16-bit CORDIC rotator for high-performance wireless LAN

In this paper we propose a novel 16-bit low power CORDIC rotator that is used for high-speed wireless LAN. The algorithm converges to the final target angle by adaptively selecting appropriate iteration steps while keeping the scale factor virtually constant. The VLSI architecture of the proposed design eliminates the entire arithmetic hardware in the angle approximation datapath and reduces the number of iterations by 50% on an average. The cell area of the processor is 0.7 mm2 and it dissipates 7 mW power at 20 MHz frequency

Dual-Carrier High-Gain Low-Noise Superlattice Avalanche Photodiodes

In this paper, novel avalanche photodiode structures with alternate carrier multiplication nanometer regions, placed next to a wider electron multiplication region, to create dual-carrier feedback systems, are proposed. Gain and excess noise factor of these structures are calculated based on the dead space multiplication theory under uniform electric field. In addition, the equivalent impact ionization ratios are derived and compared. It is observed that the proposed structures can generate much higher gain compared with conventional pure electron multiplication structures under the same electric field without severely degrading the excess noise quality. Excess noise is further optimized with careful adjustment of thin multiplication regions\u27 thicknesses. These high-gain structures can operate under low-bias (\u3c; 5 V) conditions, making it possible to integrate infrared avalanche photodiodes (APDs) directly into silicon read-out circuits. In this paper, type-II mid-wavelength infrared InAs/GaSb strained layer superlattice is used for simulation. However, the concept of dual-carrier APDs, with carrier feedback to generate high gain and control of excess noise through confining impact ionization in thin layers, is general and can also be applied to other wavelength APDs with different materials and thicknesses. Type II InAs/GaSb strain layer superlattice allows for versatile band structure design leading to impact ionization coefficient engineering