-
[show abstract]
[hide abstract]
ABSTRACT: The prolific growth of portable electronic devices (PED) has generated tremendous interests among researchers to develop programmable
phase-locked loops (PLLs) because of their abilities to produce multiple spectrally pure output frequencies from a fixed frequency
oscillator. The power consumption of the RF block of a PED is mostly dominated by the programmable PLLs which are widely used
in the design of these devices. Therefore to reduce the overall power consumption in a portable device and to increase the
battery life time, low-voltage and low-power are the two key requirements for the PLL design. In this work an improved programmable
fractional frequency divider has been incorporated to enhance the overall performance of the PLL that includes lower operating
supply voltage and lower power consumption compared to the state-of-art. The proposed programmable fractional PLL has an operating
frequency in the range of 1.7–2.5 GHz, and a frequency resolution of 2.5MHz. Measurement results reveal that the proposed
programmable PLL can operate at 2.4 GHz with a 1.46V power supply voltage and only 10 mW of power consumption.
KeywordsFractional PLL-Programmable frequency divider-Phase-locked loop-Division ratio
Analog Integrated Circuits and Signal Processing 04/2012; 65(1):33-42. · 0.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper reports a low-voltage low-power injection-locked oscillator suitable for short range wireless transmitter applications
in a wireless body area network (WBAN). Low-power transmitter with high efficiency is a major design challenge for short range
wireless communication. Unlike conventional transmitters used for cellular communication, injection-locked transmitter shows
reduced power consumption and high transmitter efficiency. The core block of an injection-locked transmitter is an injection-locked
oscillator. In this work a low-voltage low-power injection-locked LC oscillator has been designed and fabricated employing
self-cascode structure and body-terminal coupling. The proposed oscillator has been realized using 0.18-μm RF CMOS process.
Experimental results indicate that the prototype oscillator can operate with a supply voltage as low as 0.9V and consumes
only 1.4mW of power. The relatively low-voltage and low-power operation of the design makes it highly suitable for low-power
transmitter applications.
KeywordsLow-power transmitter–Injection-locked oscillator–Self-cascode structure–Body coupling
Analog Integrated Circuits and Signal Processing 04/2012; 66(2):145-154. · 0.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In oxygenic plants, photons are captured with high quantum efficiency by two specialized reaction centers (RC) called Photosystem I (PS I) and Photosystem II (PS II). The captured photon triggers rapid charge separation and the photon energy is converted into an electrostatic potential across the nanometer-scale ( ~ 6 nm) reaction centers. The exogenous photovoltages from a single PS I RC have been previously measured using the technique of Kelvin force probe microscopy (KFM). However, biomolecular photovoltaic applications require two-terminal devices. This paper presents for the first time, a micro-device for detection and characterization of isolated PS I RCs. The device is based on an AlGaN/GaN high electron mobility transistor (HEMT) structure. AlGaN/GaN HEMTs show high current throughputs and greater sensitivity to surface charges compared to other field-effect devices. PS I complexes immobilized on the floating gate of AlGaN/GaN HEMTs resulted in significant changes in the device characteristics under illumination. An analytical model has been developed to estimate the RCs of a major orientation on the functionalized gate surface of the HEMTs.
IEEE Transactions on NanoBioscience 10/2011; · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper describes a highly accurate dose control circuit (DCC) for the emission of a desired number of electrons from vertically aligned carbon nanofibers (VACNFs) in a massively parallel maskless e-beam lithography system. The parasitic components within the VACNF device cause a premature termination of the electron emission, resulting in underexposure of the photoresist. In this paper, we compensate for the effects of the parasitic components and noise while reducing the area of the chip and achieving a precise count of emitted electrons from the VACNFs to obtain the optimum dose for the e-beam lithography.
IEEE Transactions on Instrumentation and Measurement 05/2011; · 1.21 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The growing demand for hybrid electric vehicles (HEVs) has increased the need for high-temperature electronics that can operate at the extreme temperatures that exist under the hood. This paper presents a high-voltage, high-temperature SOI-based gate driver for SiC FET switches. The gate driver is designed and implemented on a 0.8-micron BCD on SOI process. This gate driver chip is intended to drive SiC power FETs for DC-DC converters and traction drives in HEVs. To this end, the gate driver IC has been successfully tested up to 200°C. Successful operation of the circuit at this temperature with minimal or no heat sink, and without liquid cooling, will help to achieve higher power-to-volume as well as power-to-weight ratios for the power electronics modules in HEVs.
Applied Power Electronics Conference and Exposition (APEC), 2011 Twenty-Sixth Annual IEEE; 04/2011
-
[show abstract]
[hide abstract]
ABSTRACT: In this work, MOSFET-embedded cantilevers are configured as microbial sensors for detection of anthrax simulants, Bacillus thuringiensis. Anthrax simulants attached to the chemically treated gold-coated cantilever cause changes in the MOSFET drain current due to the bending of the cantilever which indicates the detection of anthrax simulant. Electrical properties of the anthrax simulant are also responsible for the change in the drain current. The test results suggest a detection range of 10 μL of stimulant test solution (a suspension population of 1.3 × 10<sup>7</sup> colony-forming units/mL diluted in 40% ethanol and 60% deionized water) with a linear response of 31 μA/μL.
IEEE Electron Device Letters 04/2011; · 2.85 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper reports a low-power sensor signal processing and load shift keying (LSK) telemetry scheme for an inductively powered implant system. The entire system manifests a voltage reference (VR), a potentiostat, and a current controlled oscillator (CCO). All of the functional blocks are designed using subthreshold MOSFETs to achieve ultra-low-power consumption. Relatively simpler architecture of the VGR saves area and power. The CCO generates frequency modulated digital pulses depending upon sensor current. The proposed system has been designed and simulated in 65 nm standard CMOS process and the entire system consumes less than 20 μW.
Biomedical Wireless Technologies, Networks, and Sensing Systems (BioWireleSS), 2011 IEEE Topical Conference on; 02/2011
-
[show abstract]
[hide abstract]
ABSTRACT: High-performance wireless power transmission working as a continuous power source of implantable devices can prevent biohazard from leakage of buttery fluid or skin infection from transcutaneous cable. This work reports a high efficiency inductive powering and backward telemetry for implantable medical devices. A new differential class-E type power oscillator with high efficiency excites the external unit, the resonant link coils transfer the power to the internal unit, a modified rectifier circuit rectifies and boosts the recovered signal, and a Zener diode based voltage regulator regulates the output DC voltage. The recovered power is then used to run a ring oscillator-based sensor readout circuit to generate data signal based on sensor current variation and finally a load-shift-keying (LSK) is used to back transit the data to the external unit. The system has been designed using 0.5-μm standard CMOS process with off-chip zener diode, opamp and inductors. The over all power-efficiency of the system is found to be 74.0%.
Sensors, 2010 IEEE; 12/2010
-
[show abstract]
[hide abstract]
ABSTRACT: This work reports a vertically aligned carbon nanofiber (VACNF) based glucose detector which shows excellent selectivity without employing any mediator or artificial membrane. Forests of VACNF are fabricated on silicon (Si) substrate using plasma enhanced chemical vapor deposition (PECVD) process and a metal layer is fabricated over silicon to serve as the electrode. VACNFs demonstrate superior conductive and structural properties compared to other carbon nano-materials and serve as an excellent location for charge transfer in electrochemical reaction process. Measurement results show that this glucose sensor can detect very low level of glucose with a high degree of linearity with respect to glucose concentration. Glucose detection is often interfered by several electro-active compounds and mediators/membranes are used to improve the performance of the detectors. Test results demonstrate that the proposed glucose sensor works well in presence of the interferer materials.
Sensors, 2010 IEEE; 12/2010
-
[show abstract]
[hide abstract]
ABSTRACT: Silicon carbide (SiC)-based field effect transistors (FETs) are gaining popularity as switching elements in power electronic circuits designed for high-temperature environments like hybrid electric vehicle, aircraft, well logging, geothermal power generation etc. Like any other power switches, SiC-based power devices also need gate driver circuits to interface them with the logic units. The placement of the gate driver circuit next to the power switch is optimal for minimising system complexity. Successful operation of the gate driver circuit in a harsh environment, especially with minimal or no heat sink and without liquid cooling, can increase the power-to-volume ratio as well as the power-to-weight ratio for power conversion modules such as a DC-DC converter, inverter etc. A silicon-on-insulator (SOI)-based high-voltage, high-temperature integrated circuit (IC) gate driver for SiC power FETs has been designed and fabricated using a commercially available 0.8--m, 2-poly and 3-metal bipolar-complementary metal oxide semiconductor (CMOS)-double diffused metal oxide semiconductor (DMOS) process. The prototype circuit-s maximum gate drive supply can be 40-V with peak 2.3-A sourcing/sinking current driving capability. Owing to the wide driving range, this gate driver IC can be used to drive a wide variety of SiC FET switches (both normally OFF metal oxide semiconductor field effect transistor (MOSFET) and normally ON junction field effect transistor (JFET)). The switching frequency is 20-kHz and the duty cycle can be varied from 0 to 100-. The circuit has been successfully tested with SiC power MOSFETs and JFETs without any heat sink and cooling mechanism. During these tests, SiC switches were kept at room temperature and ambient temperature of the driver circuit was increased to 200-C. The circuit underwent numerous temperature cycles with negligible performance degradation.
IET Power Electronics 12/2010; · 1.62 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A low-voltage low-power injection-locked RF oscillator using a self-cascode structure and body terminal coupling is reported. A self-cascode structure facilitates higher resistance in each conducting path and helps achieve low-power operation without degrading the voltage headroom. Body terminal coupling provides injection-locking without appreciably increasing the power consumption. The proposed oscillator fabricated in 0.18 m RF CMOS process can operate with a supply voltage as low as 0.9 V and consumes only 1.161 mW of power for 1.30 GHz operating frequency. Relatively low power consumption makes the design highly suitable for low-power transmitter applications.
Electronics Letters 10/2010; · 0.96 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Transcutaneous power transmission is a critical issue for long term reliable operation of implantable systems. This paper reports a power-oscillator based inductive power link to power up any implantable unit inside the human body. Instead of using power amplifier which requires high drive requirement, two power-oscillator based inductive powering schemes have been presented to achieve high link efficiency. The first scheme utilizes a class-E power oscillator whereas the second scheme uses a differential cross-coupled power oscillator to drive the inductive link. Resonant inductive link has been used to achieve better link efficiency. Simulation results indicate that for a coupling coefficient of 0.45, the class-E power-oscillator based scheme shows a link efficiency of 66% and the differential cross-coupled power-oscillator based scheme shows more than 90% link efficiency. The system has been designed using 0.5-μm standard CMOS process and both of the systems can handle more than 10 mW of power which is adequate for safe operation of biomedical implants.
Circuits and Systems (MWSCAS), 2010 53rd IEEE International Midwest Symposium on; 09/2010
-
[show abstract]
[hide abstract]
ABSTRACT: Low voltage and low power are two key requirements for on-chip realization of wireless power and data telemetry for applications in biomedical sensor instrumentation. Batteryless operation and wireless telemetry facilitate robust, reliable, and longer lifetime of the implant unit. As an ongoing research work, this paper demonstrates a low-power low-voltage sensor readout circuit which could be easily powered up with an inductive link. This paper presents two versions of readout circuits that have been designed and fabricated in bulk complementary metal-oxide semiconductor (CMOS) processes. Either version can detect a sensor current in the range of 0.2 μA to 2 μA and generate square-wave data signal whose frequency is proportional to the sensor current. The first version of the circuit is fabricated in a 0.35-μ m CMOS process and it can generate an amplitude-shift-keying (ASK) signal while consuming 400 μ W of power with a 1.5-V power supply. Measurement results indicate that the ASK chip generates 76 Hz to 500 Hz frequency of a square-wave data signal for the specified sensor current range. The second version of the readout circuit is fabricated in a 0.5-μ m CMOS process and produces a frequency-shift-keying (FSK) signal while consuming 1.675 mW of power with a 2.5-V power supply. The generated data frequency from the FSK chip is 1 kHz and 9 kHz for the lowest and the highest sensor currents, respectively. Measurement results confirm the functionalities of both prototype schemes. The prototype circuit has potential applications in the monitoring of blood glucose level, lactate in the bloodstream, and pH or oxygen in a physiological system/environment.
IEEE Transactions on Biomedical Circuits and Systems 09/2010; · 2.03 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An analog signal processing integrated circuit for microcantilever array has been designed for pressure measurement in biomedical applications. The chip consists of analog multiplexer, instrumentation amplifier, sample-and-hold circuit, on-chip voltage and current references, successive approximation register analog-to-digital converter (ADC) and digital control unit. Root sum square (RSS) error from the overall pressure measurement system including microcantilever array and the application specific integrated circuit (ASIC) is only ±1.79 KPa within the measurement range of 0-300 KPa. The 8-bit ADC attains 45.4 dB signal-to-noise-and-distortion ratio (SNDR) and 56.4 dB spurious-free dynamic range (SFDR), while operating at 772 KHz. The integrated circuit has been fabricated using 0.35-¿m 2-poly 4-metal CMOS process technology. The chip occupies an area of 1.54 mm<sup>2</sup> and consumes 17.8 mW of power with a single 3.3 V supply.
IEEE Sensors Journal 03/2010; · 1.52 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A major design challenge for short-range wireless communication is a low-power transmitter with high efficiency. Unlike conventional transmitters used for cellular communication, injection-locked oscillator based transmitter shows greater promises with reduced power consumption and high transmitter efficiency. This paper presents a low-voltage low-power injection-locked oscillator (ILO) employing self-cascode structure and body-terminal coupling. The proposed oscillator has been fabricated using 0.18-¿m RF CMOS process. Measurement results indicate that the proposed oscillator can operate with a supply voltage as low as 1 V and consumes only 2 mW of power, which makes the design highly suitable for low-power transmitter applications.
Radio and Wireless Symposium (RWS), 2010 IEEE; 02/2010
-
[show abstract]
[hide abstract]
ABSTRACT: The use of vertically aligned carbon nanofibers has been found to be an effective strategy for building a biosensor platform. The VACNF structure is conducive to immobilization because of the presence of many defect sites that have exposed carboxyl groups which allow successful immobilization of the biological elements. The abundance of defect sites is not only good for immobilization but also for strong electrical current response. In this study, a mediator free amperometric bienzyme glucose biosensor is constructed by co-immobilization of horseradish peroxidase and glucose oxidase on the vertically aligned carbon nanofiber electrode. Reduction peaks have been observed due to presence of horseradish peroxidase at the VACNF electrode. High sensitivity of this biosensor to glucose has also been observed. Linear range has been found up to glucose concentration of 40 ¿M.
Semiconductor Device Research Symposium, 2009. ISDRS '09. International; 01/2010
-
[show abstract]
[hide abstract]
ABSTRACT: The authors propose a ring-based injection-locked frequency divider (ILFD) incorporating a novel process and temperature compensation technique. The core of the ILFD consists of a process and temperature compensated ring oscillator based on modified symmetric load delay elements. Measurement results show that the natural frequency of oscillation of the ring oscillator varies only 4.4% across six different chips and for a temperature range of 0%80%C. The ILFD possesses a wide locking range over process corners as well as a wide temperature range because of the proposed compensation technique and the incorporation of the delay cell architecture in the design. A calibration circuitry can be used to further enhance the locking range. Measurement results show that the proposed ILFD functions as a divide-by-4 for an input frequency range of 1.8%3.2%GHz for an input power level as low as %3%dBm. The worst-case power consumption was approximately 2%mW from a 1.8%V power supply. The proposed ILFD can be used as a low-power prescaler for multi-band applications.
IET Circuits Devices & Systems 11/2009; · 0.55 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Improving the efficiency and the power consumption of a RF transmitter in a wireless sensor network is a major design challenge. Unlike conventional transmitter architectures, injection-locked transmitter (ILTX) provides high efficiency with reduced power consumption. The core block of an ILTX is an injection-locked oscillator. Therefore this paper reports a low-voltage low-power injection-locked LC oscillator employing self-cascode structure and body-terminal coupling. Self-cascode structure of the oscillator provides low-voltage and low-power operation while body terminal coupling facilitates low-power operation without degrading voltage headroom. The proposed oscillator has been fabricated using 0.18-mum RF CMOS process. Measurement results indicate that the designed oscillator can operate with a supply voltage as low as 1 V and exhibits 36.75 MHz locking range for an injection signal of 1.29 GHz at 0 dBm. The core oscillator consumes only 2 mW of power that makes the proposed design highly suitable for low-power transmitter applications.
VLSI, 2009. ISVLSI '09. IEEE Computer Society Annual Symposium on; 06/2009
-
[show abstract]
[hide abstract]
ABSTRACT: Wireless sensors that are capable of working in extreme environments can significantly improve the efficiency and performance of industrial processes by facilitating better monitoring and control. Gallium nitride (GaN), a widely researched wide bandgap material, can potentially be used to fabricate components for sensing and actuation for high temperature integrated wireless sensors. In this paper we are presenting an experimental study on the performance of AlGaN/GaN HEMT at high temperatures (up to 300degC). From test results, DC and microwave parameters at different temperatures were extracted.
Circuits and Systems, 2008. MWSCAS 2008. 51st Midwest Symposium on; 09/2008
-
[show abstract]
[hide abstract]
ABSTRACT: This paper presents a low-power sensor read-out circuit with FSK telemetry option. The proposed system consists of a data generator block and a FSK generator block. The data generator block converts a sensor current to a square wave data signal whereas the FSK generator block produces two different frequencies depending upon the value of the data signal. The relatively simple architecture of the proposed system facilitates the low-voltage and low-power operation. The system has been designed using AMI 0.5 mum CMOS process. Simulation results show that the proposed system can detect a sensor current in the range of 50 nA to 5 muA and the total power consumption is 431 muW with a 3.3 V supply. The circuit is ready to be submitted for monolithic integration.
Circuits and Systems, 2008. MWSCAS 2008. 51st Midwest Symposium on; 09/2008
