Fusak Cheevasuvit

A full-wave rectifier using a current conveyor and current mirrors

The realization of a full-wave rectifier using a current conveyor and current mirrors is presented. The proposed rectifier is composed of a voltage-to-current converter, a current mode full-wave rectifier, and a current-to-voltage converter. A voltage input signal is changed into a current signal by the voltage-to-current converter. The current mode full-wave rectifier rectifies this current signal resulting in the current full-wave output signal that is converted into a voltage full-wave output signal by one grounded-resistor. The theory of operation is described. The simulation and experiment results are used to verify the theoretical prediction. Simulated results show that the proposed rectifier yields the minimum voltage rectification to 94µV. Experimental results demonstrate the performance of the proposed rectifier for 50mVpeak signal rectification.

CMOS dual output current mode half-wave rectifier

A CMOS dual output current mode half-wave rectifier is presented. The proposed rectifier is composed of three main components: a dual output V–I converter, two half-wave current rectifiers and two I–V converters. A voltage input signal is changed into two current signals by the V–I converter. The current rectifiers rectify these current signals, resulting in positive and negative half-wave current signals that are converted to positive and negative half-wave voltage signals by the I-Vconverters. The theory of operation is described, and the simulated results obtained from the PSPICE program are used to verify the theoretical prediction. Simulated rectifier performance with a 0.5μm MOSFET model using ±1.2V supply voltage demonstrates good rectifier integrity at operating frequencies up to 100MHz.

Enhancement of color image obtained from PCA-FCM technique using local area histogram equalization

This paper presents local area enhancement of the segmented color image obtained from the multi-spectral image clustering by using FCM (fuzzy c-means). In case, the multi-spectral images, which have the number of bands more than that of 3, must decrease the data volume to remain the number of bands of 3 in order to correspond with the meaning of red, green, and blue images. PCA (Principal Components Analysis) is then used to transform original multi-spectral images into PCA images. The first three components having information more than that of original images of 95% is assigned as red, green and blue images, namely RGB color image. FCM clustering apply to RGB color image, separately. This method is called the PCA-FCM technique being the multi-spectral image clustering. By applying such technique, the result images consisted of red, green, and blue images separately are the segmented images. By histogram equalization algorithm, the result of local area enhancement based on a number of clusters as the segmented image can solve effect of intensity saturation from global area enhancement and the perceptibility of color image is clearly improved.

Integrable CMOS-base realization of current conveyors

Simple integrable circuits for implementing both positive and negative second generation current conveyors (CCII) are described. The realization method is suitable for fabrication using CMOS technology. Simulation and experimental results demonstrating the characteristics of the method are also included.

Segmentation on edge preserving smoothing image based on graph theory

The presence of noise in an image will cause many undesired small holes in the segmented image. This effect causes an important efficiency decrease for classifying and describing objects. To remove the embedded noise while the edges of the image is still preserved, an edge preserving smoothing process must be applied. The smoothing process replaces the pixel intensity of the considered pixel by the average intensity of the most homogeneous mask among the proposed masks. The proposed masks can be preserved the thin region even its width is less than 3 pixels then, the smoothed image will be segmented by graph theory in order to obtain the higher accurate regions boundaries. In the mean time of segmentation process, the homogeneous threshold value has been applied to ensure that the maximum different gray value of each segmented region is controlled.

Progressive image transmission of variable block-size coding

The paper presents a new frontier for progressive image transmission. By applying the segmentation technique, adaptation of the pyramid structure can be improved. This method concatenates an image into a group of diverse sizes depending on its regions activity. The result is an intermediate approximation displaying an improved image. From the simulation results, the relative quality of intermediate image reconstructions, based on this proposed method, is superior to those of the existing ones, both in terms of its subjective and objective criteria. >

Fusion of principal component of multispectral bands with PAN band using HIS and wavelet transform

Since RGB images derived from multispectral (TM) images will lose some information, in this paper we present the method to solve such a problem by using principal component analysis (PCA) which transforms TM images into the principal component images (PCs), while the high resolution PAN data is decomposed by wavelet transform. Thus, RGB images are assigned by the first three principal component images which normally have approximately 95% of the information in the original images. The intensity image from RGB to HIS transformation is replaced by the lower frequency coefficient of wavelet transform of PAN data corresponding to multispectral images. HIS to RGB transformation is then applied. The fused RGB image using our method can obtain more details.

A high speed and low voltage BiCMOS tristate buffer with positive and negative charge pump

A novel high speed, low voltage BiCMOS tristate buffer is presented. The single MOS driving with pass transistor technique is used to improve the driving capability. Furthermore, the positive and negative charge pump with complementary BiCMOS technique to eliminate the voltage loss due to base-emitter turn on voltage is used to enhance the driving capability and realize high speed, low voltage with full swing operation. The simulation results have shown that it outperforms other previous tristate circuits.

Atmospheric boundary layer observation by ground-based lidar at KMITL, Thailand 13 deg N, 100 deg E

Tropospheric aerosols effects on climate in directly through various cloud formation, the lidar has been used to study the composition of many particles mixing in the atmosphere including to study the aerosol and cloud. Currently, it has many types of lidar systems depending on the purpose of measurements. In this report, the ground-based lidar system was established at King Mongkuts Institute of Technology Ladkrabang (KMITL), THAILAND to study and measure the aerosol in boundary layer and cirrus clouds in the tropopause region. The aerosol measurement is in the form of scattering ratio whereas the signal depolarization has been applied to identify layers of cirrus clouds. The lidar system consists of laser source (Nd:YAG) with second harmonic wavelength, 28 cm Schmidt-Cassegrain telescope, photomultiplier tube (PMT) and data acquisition system.

A high speed BiCMOS tristate buffer circuit

This paper presents a novel high speed BiCMOS tristate buffer for driving a large capacitive load by using the pass transistor technique to achieve a single MOS driving bipolar transistor. With a single MOS driving, it can increase the driving capability as well as reduce the number of large MOS transistors that are required to drive a bipolar compared with previous designs. In addition, the feedback circuit to achieve a full-swing operation from supply voltage to ground is added. The simulation results for the switching characteristics, rise time, fall time and base current during enable as well as the voltage waveform during disable have been presented.