Current and Voltage Mode Multiphase Sinusoidal Oscillators Using CBTAs

Current-mode (CM) and voltage-mode (VM) multiphase sinusoidal oscillator (MSO) structures using current backward transconductance amplifier (CBTA) are proposed. The proposed oscillators can generate n current or voltage signals (n being even or odd) equally spaced in phase. n+1 CBTAs, n grounded capacitors and a grounded resistor are used for nth-state oscillator. The oscillation frequency can be independently controlled through transconductance (gm) of the CBTAs which are adjustable via their bias currents. The effects caused by the non-ideality of the CBTA on the oscillation frequency and condition have been analyzed. The performance of the proposed circuits is demonstrated on third-stage and fifth-stage MSOs by using PSPICE simulations based on the 0.25 µm TSMC level-7 CMOS technology parameters

A Novel Fully Differential Second Generation Current Conveyor and Its Application as a Very High CMRR Instrumentation Amplifier

This paper aims to introduce a novel Fully Differential second generation Current Conveyor (FDCCII) and its application to design a novel Low Power (LP), very high CMRR, and wide bandwidth (BW) Current Mode Instrumentation Amplifier (CMIA). In the proposed application, CMRR, as the most important feature, has been greatly improved by using both common mode feed forward (CMFF) and common mode feedback (CMFB) techniques, which are verified by a perfect circuit analysis. As another unique quality, it neither needs well-matched active blocks nor matched resistors but inherently improves CMRR, BW, and power consumption hence gains an excellent matchless choice for integration. The FDCCII has been designed using 0.18 um TSMC CMOS Technology with ±1.2 V supply voltages. The simulation of the proposed FDCCII and CMIA have been done in HSPICE LEVEL 49. Simulation results for the proposed CMIA are as follow: Voltage CMRR of 216 dB, voltage CMRR BW of 300 Hz. Intrinsic resistance of X-terminals is only 45 Ω and the power dissipation is 383.4 μW.  Most favourably, it shows a constant differential voltage gain BW of 18.1 MHz for variable gains (here ranging from 0 dB to 45.7 dB for example) removing the bottleneck of constant gain-BW product of Voltage mode circuits

Electronically Tunable First Order AP/LP and LP/HP Filter Topologies Using Electronically Controllable Second Generation Voltage Conveyor (CVCII)

In this paper two new first order filter topologies realizing low-pass/all-pass (LP/AP) and low-pass/high-pass (LP/HP) outputs using electronically controllable second generation voltage conveyors (CVCIIs) are presented. Unlike second generation voltage conveyors (VCII), in CVCII each performance parameter, including ports, parasitic impedances, current and/or voltage gains can be electronically varied. Here, in particular, the proposed filter topologies are based on two CVCIIs, one resistor and one capacitor. In the first topology VLP/IAP/VAP and in the second topology ILP/VLP/IHP/VHP outputs are achievable, respectively. However, the current and voltage outputs are not achievable simultaneously and a floating capacitor is used. A control current (Icon) is used to change the first CVCII Y port impedance, which sets the filter −3 dB frequency (f0) of all the outputs. Moreover, in the second topology, the gains of HP and AP outputs are electronically adjusted by means of a control voltage (Vcon). Favorably, no restricting matching condition is necessary. PSpice simulations using 0.18 µm CMOS technology and supply voltages of ±0.9V show that by changing Icon from 0.5 µA to 50 µA, f0 is varied from 89 kHz to 1 MHz. Similarly, for a Vcon variation from −0.9 V to 0.185 V, the gains of IAP and IHP vary from 30 dB to 0 dB and those of VAP and VHP vary from 100 dB to 20 dB. The total harmonic distortion (THD) is about 8%. The power consumption is from 0.385 mW to 1.057 mW

Multiplexed Photometry And Fluorimetry Using Multiple Frequency Channels

ABSTRACT MULTIPLEXED PHOTOMETRY AND FLUORIMETRY USING MULTIPLE FREQUENCY CHANNELS by KHALED M. DADESH August 2013 Advisor: Dr. Amar Basu Major: Electrical Engineering Degree: Doctor of Philosophy Multispectral photometry and fluorimetry are useful for quantifying and distinguishing samples during flow injection analysis, flow cytometry, and ratiometric absorbance measurement. However, multispectral detectors, including spectrometers, typically require arrayed or multiple light detectors, optical components, and path alignments, all of which increases the size and cost of the detection system. Several previous efforts have attempted the use of time division multiplexing or frequency division multiplexing (FDM) techniques to minimize both size and cost of multispectral photometry equipment by using only a single light detector. Although many of these designs achieved low cost, they generally operated at \u3c50 KHz, which limited the detection speed of the overall system. An alternative frequency multiplexing design operated at 3MHz; however, it required electro optical modulators [50], which are too expensive and bulky for portable applications. In contrast to both approaches, the objective of this research is to use frequency division multiplexing to perform multispectral photometry and fluorimetry while achieving both low cost and high frequency operation (up to 100 MHz). The multiplexing is performed electronically using low cost optoelectronic sources, a single light detector, and a single high-throughput interrogation window. It enables us to perform multi-parameter biological analysis at lower costs and less complexity. Multiple monochromatic light sources, each with a unique wavelength, are electronically modulated at distinct frequencies, and their combined light emission is directed to the sample detection cell. The light transmitted by the sample (absorbance mode) or emitted by the sample (fluorescence mode) is directed to a single light detector. The received light is then converted to a voltage signal and demodulated into the frequency channels using phase-sensitive electronics. Each recovered channel therefore provides either absorbance or fluorescence at its respective optical wavelength. The system is designed to operate at high speed in order to be used in high throughput detectors such as flow cytometers. As a proof of concept, we apply the FDM technique in two detection systems: 1) a three-color absorbance photometry detector and 2) a two-color laser induced fluorescence (LIF) detector. In the first system, three LEDs are operated with 150 KHz, 200 KHz, and 250 KHz modulation frequencies, and the system achieves a 1 ms measurement time constant at an overall component cost \u3c$10. We perform absorbance photometry of four different organic dyes in flow injected solutions and in discrete droplet microreactors with throughputs in the 10\u27s of samples per second. In both cases, the system is able to simultaneously discriminate between them [13]. In the LIF system, first two laser diodes operated at 1 KHz and 1.5 KHz, respectively, are used to excite fluorophores at the respective frequencies. This system is able to distinguish low speed (1 drop/sec) water-in-oil droplets containing fluorescein or rhodamine-6G generated in a microfluidic junction. Second two laser diodes operated at 25MHz and 40 MHz, respectively, are controlled using a developed high frequency FDM system to excite Fluorescein and Alexa 680 dyes at the respective frequencies. Because of the high frequency operation, this system is able to distinguish alternating high speed (300 drops/sec) droplets containing the two fluorescent dyes. In both case, the developed In previous experiments we use an inverted fluorescence microscope with a specific optical cube to excite dyes and collect fluorescence signals. These two FDM-LIF systems identify the different fluorophores based on their excitation frequency rather than their emission band, giving it a unique ability to distinguish fluorophores with overlapping emission spectra. However, overlapping excitation spectra is a problem in the FDM-LIF system, and any assay has to be prepared using fluorophores with minimal excitation overlap. Therefore, fluorophores with sharp excitation lines such as lanthanide ions are the best candidate material in use with FDM-LIF system. The system uses high frequency (100 MHz) modulation which enables multiplexed time constants on the order of 1 µs. Achieving this high bandwidth allow us to apply the system towards high throughput analysis such as cell cytometry, where it could substantially reduce cost and size of the system. Therefore, the FDM-LIF system is installed in an old BD bioscience cytometer, which is available in the cell cytometry laboratory in Karmanos Cancer Research Center (KCRC) located at Detroit Medical Center (DMC). A biological assay containing Alexa Fluor® 680 Goat Anti-Mouse IgG (H+L) and Alexa Fluor® 430 Goat Anti-Mouse IgG (H+L) with BDTM CompBead Anti-mouse Ig, κ beads is tested using the FDM-LIF system. The system is capable to count the two different antigens simultaneously, which gives the possibility of incorporating this system in cytometers. This technology promises to reduce cost and complexity of future cytometers

Dual-mode multifunction filter realized with a single voltage differencing gain amplifier (VDGA)

This article presents the dual-mode multifunction biquad filter realized employing only a single voltage differencing gain amplifier (VDGA), one resistor and three capacitors. The proposed filterwith one input and three outputs can configure as voltage-mode or current-mode filter circuit with the appropriate input injection choice. It can also synthesis the three standard filter functions, which are highpass, bandpass, and lowpass responses without modifying the circuit configuration. Orthogonal adjustment between the natural angular frequency (o) and the quality factor (Q) of the filter is achieved. Detail analysis of non-ideal VDGA effects and circuit component sensitivity are included. The circuit principle is verified by means of simulation results with TSMC 0.35-m CMOS process parameters

Reconfigurable of current-mode differentiator and integrator based-on current conveyor transconductance amplifiers

The reconfigurable of the differentiator and integrator based on current conveyor transconductance amplifiers (CCTAs) have been presented in this paper. The proposed configurations are provided with two CCTAs and grounded elements. The configurations can be operated in the differentiator and integrator by selecting external passive elements. The input and output currents have low and high impedances, respectively; therefore, the configurations can be cascaded without additional current buffer. The proposed configurations can be electronically tuned by external direct current (DC) bias currents, and it also has slight fluctuation with temperature. An application of universal filter is demonstrated to confirm the ability of the proposed configurations. The results of simulation with Pspice program are accordance with the theoretical analysis

Communication Subsystems for Emerging Wireless Technologies

The paper describes a multi-disciplinary design of modern communication systems. The design starts with the analysis of a system in order to define requirements on its individual components. The design exploits proper models of communication channels to adapt the systems to expected transmission conditions. Input filtering of signals both in the frequency domain and in the spatial domain is ensured by a properly designed antenna. Further signal processing (amplification and further filtering) is done by electronics circuits. Finally, signal processing techniques are applied to yield information about current properties of frequency spectrum and to distribute the transmission over free subcarrier channels

Circuits for Analog Signal Processing Employing Unconventional Active Elements

Disertační práce se zabývá zaváděním nových struktur moderních aktivních prvků pracujících v napěťovém, proudovém a smíšeném režimu. Funkčnost a chování těchto prvků byly ověřeny prostřednictvím SPICE simulací. V této práci je zahrnuta řada simulací, které dokazují přesnost a dobré vlastnosti těchto prvků, přičemž velký důraz byl kladen na to, aby tyto prvky byly schopny pracovat při nízkém napájecím napětí, jelikož poptávka po přenosných elektronických zařízeních a implantabilních zdravotnických přístrojích stále roste. Tyto přístroje jsou napájeny bateriemi a k tomu, aby byla prodloužena jejich životnost, trend navrhování analogových obvodů směřuje k stále většímu snižování spotřeby a napájecího napětí. Hlavním přínosem této práce je návrh nových CMOS struktur: CCII (Current Conveyor Second Generation) na základě BD (Bulk Driven), FG (Floating Gate) a QFG (Quasi Floating Gate); DVCC (Differential Voltage Current Conveyor) na základě FG, transkonduktor na základě nové techniky BD_QFG (Bulk Driven_Quasi Floating Gate), CCCDBA (Current Controlled Current Differencing Buffered Amplifier) na základě GD (Gate Driven), VDBA (Voltage Differencing Buffered Amplifier) na základě GD a DBeTA (Differential_Input Buffered and External Transconductance Amplifier) na základě BD. Dále je uvedeno několik zajímavých aplikací užívajících výše jmenované prvky. Získané výsledky simulací odpovídají teoretickým předpokladům.The dissertation thesis deals with implementing new structures of modern active elements working in voltage_, current_, and mixed mode. The functionality and behavior of these elements have been verified by SPICE simulation. Sufficient numbers of simulated plots are included in this thesis to illustrate the precise and strong behavior of those elements. However, a big attention to implement active elements by utilizing LV LP (Low Voltage Low Power) techniques is given in this thesis. This attention came from the fact that growing demand of portable electronic equipments and implantable medical devices are pushing the development towards LV LP integrated circuits because of their influence on batteries lifetime. More specifically, the main contribution of this thesis is to implement new CMOS structures of: CCII (Current Conveyor Second Generation) based on BD (Bulk Driven), FG (Floating Gate) and QFG (Quasi Floating Gate); DVCC (Differential Voltage Current Conveyor) based on FG; Transconductor based on new technique of BD_QFG (Bulk Driven_Quasi Floating Gate); CCCDBA (Current Controlled Current Differencing Buffered Amplifier) based on conventional GD (Gate Driven); VDBA (Voltage Differencing Buffered Amplifier) based on GD. Moreover, defining new active element i.e. DBeTA (Differential_Input Buffered and External Transconductance Amplifier) based on BD is also one of the main contributions of this thesis. To confirm the workability and attractive properties of the proposed circuits many applications were exhibited. The given results agree well with the theoretical anticipation.

The electronic instrumentation for atmospheric laser propagation studies

The use of laser radiation in atmospheric communication systems is revealing new forms of signal degradation not previously encountered with lower frequency transmitting sources. The coherence and directivity of the laser which is responsible for its increased signal capacity is degraded by the effect of atmospheric distortion. Random fluctuations in the index of refraction (turbulence), Rayleigh scattering, aerosol scattering and other atmospheric effects create fluctuations (boiling, breathing, dancing, attenuation, transit-time dispersion, etc.) within the beam cross section, which when received produce random fluctuations in the receiver output signal. The two systems which are described, are designed to investigate the effect of atmospheric distortions on the amplitude and phase (or transit time) of the laser beam. The Scintillation System was designed for real-time determination of amplitude scintillation statistics. The system will be incorporated into a multi-wavelength, multi-range experiment for comparison of theoretical and experimental meteorological and optical data. The system includes a laser transmitter, an atmospheric path over which the beam is allowed to diverge to a three-foot cross section, a pair of photomultipliers with variable spacing and small sampling apertures, an analog scintillation computer, and a recording device. The scintillation computer is a real time, special purpose, analog computer designed to compute the variance and covariance of log amplitude, the probability distribution of log amplitude, and the frequency spectrum of the amplitude scintillation. The system permits the recording of these data as a function of transmitter and receiver aperture, and time. The Short Pulse Distortion System is designed to detect pulse distortion due to transit-time dispersion of the laser beam. The system includes a mode-locked laser (i.e., the optical short pulse generator), a large transmitting aperture (a Cassegrainian telescope), the atmospheric path, a wideband receiver, a sampling oscilloscope, the Pulse Distortion Analyzer, and a high-quality tape recorder. The Pulse Distortion Analyzer is designed to compare the transmitted pulses to recorded reference pulses and to detect differential area due to time dispersion. The analyzer includes a novel, feed forward, automatic gain control circuit which utilizes a linear photo detector and an analog divider to smooth a 300Hz signal with a 100 microsecond response time. This is necessary to smooth out the signal amplitude fluctuations due to atmospheric turbulence effects. Both systems have been set up and tested on a one-mile path between the Oregon Graduate Center and Skyline Drive in Portland Oregon, using a 6328Å He-Ne Laser. The ultimate use of the scintillation computer will be in a multi-wave-length experiment conducted for the Office of Naval Research, and will utilize a uniform, meteorologically instrumented path for comparison with theoretical predictions. The Pulse Distortion System will be incorporated into a joint experiment with the Electro-optic Organization of Sylvania Electronic Systems, Inc., Mountain View, California, to be conducted over a seven-mile path

Robust low power CMOS methodologies for ISFETs instrumentation

I have developed a robust design methodology in a 0.18 [Mu]m commercial CMOS process to circumvent the performance issues of the integrated Ions Sensitive Field Effect Transistor (ISFET) for pH detection. In circuit design, I have developed frequency domain signal processing, which transforms pH information into a frequency modulated signal. The frequency modulated signal is subsequently digitized and encoded into a bit-stream of data. The architecture of the instrumentation system consists of a) A novel front-end averaging amplifier to interface an array of ISFETs for converting pH into a voltage signal, b) A high linear voltage controlled oscillator for converting the voltage signal into a frequency modulated signal, and c) Digital gates for digitizing and differentiating the frequency modulated signal into an output bit-stream. The output bit stream is indistinguishable to a 1st order sigma delta modulation, whose noise floor is shaped by +20dB/decade. The fabricated instrumentation system has a dimension of 1565 [Mu] m 1565 [Mu] m. The chip responds linearly to the pH in a chemical solution and produces a digital output, with up to an 8-bit accuracy. Most importantly, the fabricated chips do not need any post-CMOS processing for neutralizing any trapped-charged effect, which can modulate on-chip ISFETs’ threshold voltages into atypical values. As compared to other ISFET-related works in the literature, the instrumentation system proposed in this thesis can cope with the mismatched ISFETs on chip for analogue-to-digital conversions. The design methodology is thus very accurate and robust for chemical sensing