Quazi Delwar Hossain

Design and Characterization of Current-Assisted Photonic Demodulators in 0.18-

We report on the design of a current-assisted photonic demodulator (CAPD) using standard 0.18-μm complementary metal-oxide-semiconductor technology and its electrooptical characterization. The device can perform both light detection and demodulation in the charge domain, owing to a drift field generated in the silicon substrate by a majority carrier flow. Minimum-sized 10 × 10 μm2 CAPDs exhibit a direct-current charge-transfer efficiency larger than 80% (corresponding to demodulation contrast larger than 40% under sine-wave modulation) at the modest power consumption of 10 μW and a 3-dB bandwidth of >; 45 MHz. An excellent linearity value with an error lower than 0.11% is obtained in phase measurements. CAPDs with optimized modulation electrode geometries are finally designed, aiming at an improved contrast-versus-power tradeoff.

\mu\hbox{m}

A new circularly polarized planar array antenna using linearly polarized microstrip patches is designed and optimized for X-band wireless communication applications. Four square patch elements with feed network are used to design the circularly polarized array antenna. The feed network consists of microstrip lines on the obverse side of the dielectric substrate and slot line on the reverse side of the substrate. Both-sided MIC technology is successfully employed to apply its inherent advantages in the design process of the array structure. The unequal feed line is used to create 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. Characteristics of the proposed array are investigated by using two electromagnetic (EM) simulators: advanced design system and EMPro. The −10 dB impedance bandwidth of the antenna is around 5%. The 3 dB axial ratio bandwidth of 1.48% is obtained. The design of the proposed antenna along with parametric study is presented and discussed.

CMOS Technology

In this paper, the design of a circularly polarized array antenna at 10 GHz frequency is presented. The proposed antenna consists of a 1×2 array antenna with feed circuit. To realize circular polarization, dual-orthogonal feed circuit is used that excites two orthogonal modes with equal amplitude but quadrature in phase. Feed circuit is designed using microstrip lines and slot lines where microstrip lines are placed on the top surface of the substrate and slot lines on the reverse side of the substrate. The feed point is chosen in such a way that it provides the each patch element two RF signals with 90° phase difference. Therefore, the circular polarization is realized by employing microstrip-slot feed circuit. “Both-Sided MIC Technology” is used to design the proposed array antenna as it gives flexibility in the design process. The simulated return loss of the proposed array antenna is less than -45 dB at the design frequency. The 3 dB axial ratio bandwidth of 0.8% is obtained. The structure and the basic behavior along with the simulation results of the proposed circularly polarized array antenna are demonstrated in this paper.

Design and parametric analysis of a planar array antenna for circular polarization

Due to low cost, low power consumption and better on-chip functionality CMOS Image Sensor has become the main image sensor for consumer electronics, machine vision as well as in research applications. Besides the advantages, a CMOS image sensor suffers from noises, less sensitivity as well as lacks of Dynamic Range (DR). Logarithmic response Active Pixel Sensor (APS) is a solution for wide dynamic range imager maintaining high fill factor. 3T Linear APS (Active Pixel Sensor) has better performance in low illumination, but very poor sensitivity in low illumination. For 3T logarithmic APS has satisfactory performance in high illumination, but limited sensitivity in low illumination. Few reported to implement both linear and logarithmic capture for a single frame which increases the capture time. Implementation of in-pixel circuitry to combine both linear and logarithmic in a single capture which decreases the fill factor of the pixel is also reported. In this paper, we propose a self-adjusting pixel to combine linear and logarithmic response maintaining high fill factor. The proposed pixel was simulated in Cadence Virtuoso in 180nm technology node and analyzed for comparative study of dynamic range.

Design of a circular polarization array antenna with dual-orthogonal feed circuit

Design of a microstrip array antenna to achieve dual circular polarization is proposed in this paper. The proposed antenna is a 2×2 array antenna where each patch element is circularly polarized. The feed network has microstrip lines, cross slot lines and air-bridges. The array antenna can excite both right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) without using any 90° hybrid circuit or PIN diode. “Both-sided MIC Technology” is used to design the feed network as it provides flexibility to place several types of transmission lines on both sides of the dielectric substrate. The design frequency of the proposed array antenna is 10 GHz. The simulated return loss exhibits an impedance bandwidth of greater than 5% and the 3-dB axial ratio bandwidths for both RHCP and LHCP are approximately 1.39%. The structure and the basic operation along with the simulation results of the proposed dual circularly polarized array antenna are demonstrated in this paper.

A self-adjusting Lin-Log active pixel for wide dynamic range CMOS image sensor

This paper describes an effort to design and characterize a patch antenna with circular polarization by using a single feeding technique instead of multiple feeding or any switching devices or couplers. Here a single feed is split into three feed lines to ensure orthogonal modes on each radiating patches. Both-sided MIC technology is used to realize the proposed array antenna. The proposed antenna consists of 4 patch elements and microstrip feed lines on the obverse side of the Teflon dielectric substrate. The ground plane and the slot lines are on the reverse side of the substrate. The dielectric constant er is 2.15. The antenna is able to radiate at 10 GHz (X band) which is demonstrated and verified through proper simulation technique.

Design of a dual circular polarization microstrip patch array antenna

This paper presents a new circularly polarized array antenna using linearly polarized microstrip patches with a gain of 7.47 dBi. The array structure consists of four square patch antennas with feed network. The feed network is designed using microstrip lines on the obverse side of the dielectric substrate and slot line on the reverse side of the substrate. The Teflon glass fiber substrate is used with a permittivity of 2.15. The design frequency of the proposed array antenna is 10 GHz where simulated return loss is less than -45dB. The unequal feed line is used in order to realize 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. Advanced Design Systems (ADS) by Agilent Technologies is used for the simulation of the proposed array antenna.

Design of a circular polarization array antenna using triple feed structure

In this paper, the design of a circularly polarized array antenna with 9.56 dBi of gain at 10 GHz frequency is presented. The proposed antenna consists of a 2×2 array antenna with feed network where all microstrip patches are linearly polarized. “Both-Sided MIC Technology” is used to design the proposed array antenna. The simulated return loss of the proposed array antenna is less than -35dB. The 3 dB axial ratio bandwidth of 2.21% is obtained. The unequal feed line is used in order to realize 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. The structure and the basic behavior along with the simulation results of the proposed linearly polarized array antenna are demonstrated in this paper.

Design of a circular polarization array antenna using linear polarization patches

In this paper, a 4-element circular polarization switchable patch array antenna is proposed. The array antenna is realized by the successful employment of the both-sided MIC technology, where the odd and even mode of the slot line and microstrip lines are used for the realization of the orthogonal feed and magic-T switching circuit respectively. The advantage of the magic-T circuit is the excellent isolation between the RF signal and the switching signal. In order to realize the polarization switching, two switching diodes are integrated with each patch elements. Unequal feed line is introduced to realize 90° phase difference between the patch elements and this way, circular polarization switchable array antenna can be realized. The array antenna unit is realized in very simple and compact structure as all the antenna elements, feeding circuit and switching circuit are arranged on both sides of a Teflon glass fiber substrate. The structure and the basic behavior of the circular polarization switchable array antenna are demonstrated in this paper. In addition, the simulated S-parameters and the phase difference of the feed circuit are explained.

Design of an x-band microstrip array antenna for circular polarization

In this paper a multiple strip photo mixing demodulator fabricated on high resistivity silicon is described. The performance such as DC characteristics, demodulation contrast and non-linearity problem of a test sample are simulated and experimentally estimated. The experimental results exhibit a good DC charge separation and good dynamic demodulation capabilities up to 30MHz. The influence of modulation frequency and voltage on this device is also discussed. This test device corresponds to the first step towards incorporating a high resolution Time of Flight (TOF) based 3D image sensor.