Mohammad Arif Sobhan Bhuiyan

Designing a ring-VCO for RFID transponders in 0.18 μm CMOS process.

In radio frequency identification (RFID) systems, performance degradation of phase locked loops (PLLs) mainly occurs due to high phase noise of voltage-controlled oscillators (VCOs). This paper proposes a low power, low phase noise ring-VCO developed for 2.42 GHz operated active RFID transponders compatible with IEEE 802.11 b/g, Bluetooth, and Zigbee protocols. For ease of integration and implementation of the module in tiny die area, a novel pseudodifferential delay cell based 3-stage ring oscillator has been introduced to fabricate the ring-VCO. In CMOS technology, 0.18 μm process is adopted for designing the circuit with 1.5 V power supply. The postlayout simulated results show that the proposed oscillator works in the tuning range of 0.5–2.54 GHz and dissipates 2.47 mW of power. It exhibits a phase noise of −126.62 dBc/Hz at 25 MHz offset from 2.42 GHz carrier frequency.

A low voltage VGA for RFID receivers

RFID is a worldwide attractive technology for reliable wireless communication system. Automatic gain control system of such devices is very important which is performed by Variable Gain Amplifier (VGA). In this paper, a class AB VGA, consisting of a linear transconductor amplifier and a linear transimpedance amplifier, is designed and simulated in CEDEC (software for design and simulation of ICs) 0.18-μm CMOS process for low power and high speed RFID receivers. The simulation result show that, the proposed VGA has a wide bandwidth of 100 MHz and dissipates power less than 125 uW at 1 V supply voltage. From the results it is also apparent that the circuit is capable of working with high linearity and wide bandwidth. Good frequency response (Gain) and the wide bandwidth of this class AB VGA makes it suitable for low power RFID receiver transceivers.

Active inductor based fully integrated CMOS transmit/ receive switch for 2.4 GHz RF transceiver

Modern Radio Frequency (RF) transceivers cannot be imagined without high-performance (Transmit/Receive) T/R switch. Available T/R switches suffer mainly due to the lack of good trade-off among the performance parameters, where high isolation and low insertion loss are very essential. In this study, a T/R switch with high isolation and low insertion loss performance has been designed by using Silterra 0.13µm CMOS process for 2.4GHz ISM band RF transceivers. Transistor aspect ratio optimization, proper gate bias resistance, resistive body floating and active inductor-based parallel resonance techniques have been implemented to achieve better trade-off. The proposed T/R switch exhibits 0.85dB insertion loss and 45.17dB isolation in both transmit and receive modes. Moreover, it shows very competitive values of power handling capability (P1dB) and linearity (IIP3) which are 11.35dBm and 19.60dBm, respectively. Due to avoiding bulky inductor and capacitor, the proposed active inductor-based T/R switch became highly compact occupying only 0.003mm2 of silicon space; which will further trim down the total cost of the transceiver. Therefore, the proposed active inductor-based T/R switch in 0.13µm CMOS process will be highly useful for the electronic industries where low-power, high-performance and compactness of devices are the crucial concerns.

A Novel Vehicle Stationary Detection Utilizing Map Matching and IMU Sensors

Precise navigation is a vital need for many modern vehicular applications. The global positioning system (GPS) cannot provide continuous navigation information in urban areas. The widely used inertial navigation system (INS) can provide full vehicle state at high rates. However, the accuracy diverges quickly in low cost microelectromechanical systems (MEMS) based INS due to bias, drift, noise, and other errors. These errors can be corrected in a stationary state. But detecting stationary state is a challenging task. A novel stationary state detection technique from the variation of acceleration, heading, and pitch and roll of an attitude heading reference system (AHRS) built from the inertial measurement unit (IMU) sensors is proposed. Besides, the map matching (MM) algorithm detects the intersections where the vehicle is likely to stop. Combining these two results, the stationary state is detected with a smaller timing window of 3 s. A longer timing window of 5 s is used when the stationary state is detected only from the AHRS. The experimental results show that the stationary state is correctly identified and the position error is reduced to 90% and outperforms previously reported work. The proposed algorithm would help to reduce INS errors and enhance the performance of the navigation system.

Low power D flip-flop serial in/parallel out based shift register

The paper demonstrates the circuit of a low power D flip-flop serial in/parallel out (DFF SIPO) based shift register design. The flip-flops (FFs) consumption of casual logic power in a SoC chip (system on chip) commonly overpasses 50% as long the input and the output are in the same state thanks to the redundancy transition of interior loops. Conventional implementation of shift register systems such as linear feedback shift registers (LFSR) have two main drawbacks namely that elements into structure have been clocked during every clock cycle, and throughput is confined to just one (1) bit per clock cycle. Large scale integrated systems have much higher power consumption when tested due to the increased level of circuit activity. The higher rate of circuit activity can help reduce transition times that are from the input to the output phases. Flip-flops have been performed in 0.18μm CMOS technology. Circuit simulations with displays showing appropriate power dissipations have been reduced are possible where input signals decrease switching activities. A 16-Bit shift register is shown as an easy low power usage.

Attitude Heading Reference System based vehicle stationary state detection

Vehicle navigation is a crucial requirement for many applications. Global Positioning System (GPS) can provide accurate navigation information. But the GPS performance degrades and even a complete outage may occur in urban areas due to line of sight problem. Inertial Navigation System (INS) can provide navigation information during a GPS outage. However, due to bias, drift, noise and other errors, the position information quickly diverges which is more sever for low cost INS. These errors can be corrected in a stationary state. Detecting the stationary state to correct the INS error is crucial for navigation system. This paper proposes a novel stationary detection technique by the threshold approach with an Attitude Heading Reference System (AHRS) built from the Inertial Measurement Unit (IMU) sensors and acceleration information. The stationary state is detected from variance of the acceleration data and the heading of the vehicle. The test result shows that the 87% correct stationary state is detected from both the acceleration and heading information. The stationary state detection can help to correct the INS errors.

Studies on optical characteristics of CuInSe2 thin films

CuInSe2 is considered as a striking semiconductor for second generation solar cells. An investigation of optical properties of CuInSe2 thin films is essential to evaluate its perfectibility as high efficiency solar cells. The films were fabricated by thermal co-evaporation technique. For this experiment, a shimadzu spectrophotometer of model number 1201 is used. The optical properties of these films are determined for the wavelength range 350 nm–1100 nm. From the experiment it is evident that the reflectance and transmittance of the films are negligible in comparison to the absorption of these films. The high absorption coefficient of the order of 104/cm of the film material also supports this. The band gap of the CuInSe2 films was evaluated to be 1.1 eV. From XRD and EDAX analysis it is evident that CuInSe2 films are polycrystalline in nature having ideal stoichiometric composition.

GPS/GSM based low altitude rotary wing aircraft tracking system

Radar and radio cannot pickup the low flying aircraft due to the limitation of radar horizon, which severely poses flight hazards. As such, tracking of the low altitude aircraft in real-time is a dire need. Global Navigation Satellite System (GNSS) receiver can provide position from the satellites. On the other hand, Global System for Mobile Communications (GSM) network, although works on the principle of line of sight, can transmit SMS or GPRS data at low altitude. This project proposes the real-time tracking of a low altitude flying rotor aircraft from GNSS position information transmitted over the GSM network. The problem of non-availability of GSM network for a particular network operator is solved by a dual SIM capable GSM modem. An algorithm will look for the signal strength and will transmit position information via the available stronger operator. The position information sent by the SMS/GPRS data will be received at the Control Center by another GSM modem. The position information will be displayed in a Google Map with the height, speed, time, etc. During a complete communication outage, the positioning data will be stored and transmitted during the availability of GSM network. Thus, the proposed system will be able to offer uninterrupted real time location information of a low flying aircraft.

Low power delay locked-loop using 0.13μm CMOS technology

In this paper, a low power delay locked-loop with modified voltage-controlled delay cell (VCDC) is proposed. This modified VCDC is designed by using Mentor Graphic CEDEC design kit and Silterra 0.13μm process technology. Thus, the DLL with proposed VCDC able to obtained low power dissipation which is 921.57μW and occupied very smaller area which is 0.03mm2.

A study on low power phase frequency detectors for delay locked loop

Delay Locked Loops (DLL) adapted in various applications due to its low power characteristics. Aggressive power demand in sensors, medical devices and new communications applications with embedded DLL has affected by Phase Frequency Detector (PFD) design techniques. This paper presents a review of various PFD in DLL design based on their main parameters including dynamic logic PFD topologies, PFD important parameters and issues total power consumption as well as their design trade-offs. This review paper gives a guideline to the future researchers for designing high speed and low power PFD.