538 research outputs found
A Novel (DDCC-SFG)-Based Systematic Design Technique of Active Filters
This paper proposes a novel idea for the synthesis of active filters that is based on the use of signal-flow graph (SFG) stamps of differential difference current conveyors (DDCCs). On the basis of an RLC passive network or a filter symbolic transfer function, an equivalent SFG is constructed. DDCCsâ SFGs are identified inside the constructed âactiveâ graph, and thus the equivalent circuit can be easily synthesized. We show that the DDCC and its âderivativesâ, i.e. differential voltage current conveyors and the conventional current conveyors, are the main basic building blocks in such design. The practicability of the proposed technique is showcased via three application examples. Spice simulations are given to show the viability of the proposed technique
Unconventional Circuit Elements for Ladder Filter Design
KmitoÄtovĂ© filtry jsou lineĂĄrnĂ elektrickĂ© obvody, kterĂ© jsou vyuĆŸĂvĂĄny v rĆŻznĂœch oblastech elektroniky. SouÄasnÄ tvoĆĂ zĂĄkladnĂ stavebnĂ bloky pro analogovĂ© zpracovĂĄnĂ signĂĄlĆŻ. V poslednĂ dekĂĄdÄ bylo zavedeno mnoĆŸstvĂ aktivnĂch stavebnĂch blokĆŻ pro analogovĂ© zpracovĂĄnĂ signĂĄlĆŻ. StĂĄle vĆĄak existuje potĆeba vĂœvoje novĂœch aktivnĂch souÄĂĄstek, kterĂ© by poskytovaly novĂ© moĆŸnosti a lepĆĄĂ parametry. V prĂĄci jsou diskutovĂĄny rĆŻznĂ© aspekty obvodĆŻ pracujĂcĂch v napÄĆ„ovĂ©m, proudovĂ©m a smĂĆĄnĂ©m mĂłdu. PrĂĄce reaguje na dneĆĄnĂ potĆebu nĂzkovĂœkonovĂœch a nĂzkonapÄĆ„ovĂœch aplikacĂ pro pĆenosnĂ© pĆĂstroje a mobilnĂ komunikaÄnĂ systĂ©my a na problĂ©my jejich nĂĄvrhu. PotĆeba tÄchto vĂœkonnĂœch nĂzkonapÄĆ„ovĂœch zaĆĂzenĂ je vĂœzvou nĂĄvrhĂĄĆĆŻ k hledĂĄnĂ novĂœch obvodovĂœch topologiĂ a novĂœch nĂzkonapÄĆ„ovĂœch technik. V prĂĄci je popsĂĄna Ćada aktivnĂch prvkĆŻ, jako napĆĂklad operaÄnĂ transkonduktanÄnĂ zesilovaÄ (OTA), proudovĂœ konvejor II. generace (CCII) a CDTA (Current Differencing Transconductance Amplifier). DĂĄle jsou navrĆŸeny novĂ© prvky, jako jsou VDTA (Voltage Differencing Transconductance Amplifier) a VDVTA (Voltage Differencing Voltage Transconductance Amplifier). VĆĄechny tyto prvky byly rovnÄĆŸ implementovĂĄny pomocĂ "bulk-driven" techniky CMOS s cĂlem realizace nĂzkonapÄĆ„ovĂœch aplikacĂ. Tato prĂĄce je rovnÄĆŸ zamÄĆena na nĂĄhrady klasickĂœch induktorĆŻ syntetickĂœmi induktory v pasivnĂch LC pĆĂÄkovĂœch filtrech. Tyto nĂĄhrady pak mohou vĂ©st k syntĂ©ze aktivnĂch filtrĆŻ se zajĂmavĂœmi vlastnostmi.Frequency filters are linear electric circuits that are used in wide area of electronics. They are also the basic building blocks in analogue signal processing. In the last decade, a huge number of active building blocks for analogue signal processing was introduced. However, there is still the need to develop new active elements that offer new possibilities and better parameters. The current-, voltage-, or mixed-mode analog circuits and their various aspects are discussed in the thesis. This work reflects the trend of low-power (LP) low-voltage (LV) circuits for portable electronic and mobile communication systems and the problems of their design. The need for high-performance LV circuits encourages the analog designers to look for new circuit architectures and new LV techniques. This thesis presents various active elements such as Operational Transconductance Amplifier (OTA), Current Conveyor of Second Generation (CCII), and Current Differencing Transconductance Amplifier (CDTA), and introduces novel ones, such as Voltage Differencing Transconductance Amplifier (VDTA) and Voltage Differencing Voltage Transconductance Amplifier (VDVTA). All the above active elements were also designed in CMOS bulk-driven technology for LP LV applications. This thesis is also focused on replacement of conventional inductors by synthetic ones in passive LC ladder filters. These replacements can lead to the synthesis of active filters with interesting parameters.
Circuits for Analog Signal Processing Employing Unconventional Active Elements
DisertaÄnĂ prĂĄce se zabĂœvĂĄ zavĂĄdÄnĂm novĂœch struktur modernĂch aktivnĂch prvkĆŻ pracujĂcĂch v napÄĆ„ovĂ©m, proudovĂ©m a smĂĆĄenĂ©m reĆŸimu. FunkÄnost a chovĂĄnĂ tÄchto prvkĆŻ byly ovÄĆeny prostĆednictvĂm SPICE simulacĂ. V tĂ©to prĂĄci je zahrnuta Ćada simulacĂ, kterĂ© dokazujĂ pĆesnost a dobrĂ© vlastnosti tÄchto prvkĆŻ, pĆiÄemĆŸ velkĂœ dĆŻraz byl kladen na to, aby tyto prvky byly schopny pracovat pĆi nĂzkĂ©m napĂĄjecĂm napÄtĂ, jelikoĆŸ poptĂĄvka po pĆenosnĂœch elektronickĂœch zaĆĂzenĂch a implantabilnĂch zdravotnickĂœch pĆĂstrojĂch stĂĄle roste. Tyto pĆĂstroje jsou napĂĄjeny bateriemi a k tomu, aby byla prodlouĆŸena jejich ĆŸivotnost, trend navrhovĂĄnĂ analogovĂœch obvodĆŻ smÄĆuje k stĂĄle vÄtĆĄĂmu sniĆŸovĂĄnĂ spotĆeby a napĂĄjecĂho napÄtĂ. HlavnĂm pĆĂnosem tĂ©to prĂĄce je nĂĄvrh novĂœch CMOS struktur: CCII (Current Conveyor Second Generation) na zĂĄkladÄ BD (Bulk Driven), FG (Floating Gate) a QFG (Quasi Floating Gate); DVCC (Differential Voltage Current Conveyor) na zĂĄkladÄ FG, transkonduktor na zĂĄkladÄ novĂ© techniky BD_QFG (Bulk Driven_Quasi Floating Gate), CCCDBA (Current Controlled Current Differencing Buffered Amplifier) na zĂĄkladÄ GD (Gate Driven), VDBA (Voltage Differencing Buffered Amplifier) na zĂĄkladÄ GD a DBeTA (Differential_Input Buffered and External Transconductance Amplifier) na zĂĄkladÄ BD. DĂĄle je uvedeno nÄkolik zajĂmavĂœch aplikacĂ uĆŸĂvajĂcĂch vĂœĆĄe jmenovanĂ© prvky. ZĂskanĂ© vĂœsledky simulacĂ odpovĂdajĂ teoretickĂœm pĆedpokladĆŻm.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.
Power-efficient current-mode analog circuits for highly integrated ultra low power wireless transceivers
In this thesis, current-mode low-voltage and low-power techniques have been applied to implement novel analog circuits for zero-IF receiver backend design, focusing on amplification, filtering and detection stages. The structure of the thesis follows a bottom-up scheme: basic techniques at device level for low voltage low power operation are proposed in the first place, followed by novel circuit topologies at cell level, and finally the achievement of new designs at system level.
At device level the main contribution of this work is the employment of Floating-Gate (FG) and Quasi-Floating-Gate (QFG) transistors in order to reduce the power consumption. New current-mode basic topologies are proposed at cell level: current mirrors and current conveyors. Different topologies for low-power or high performance operation are shown, being these circuits the base for the system level designs.
At system level, novel current-mode amplification, filtering and detection stages using the former mentioned basic cells are proposed. The presented current-mode filter makes use of companding techniques to achieve high dynamic range and very low power consumption with for a very wide tuning range. The amplification stage avoids gain bandwidth product achieving a constant bandwidth for different gain configurations using a non-linear active feedback network, which also makes possible to tune the bandwidth. Finally, the proposed current zero-crossing detector represents a very power efficient mixed signal detector for phase modulations. All these designs contribute to the design of very low power compact Zero-IF wireless receivers.
The proposed circuits have been fabricated using a 0.5ÎŒm double-poly n-well CMOS technology, and the corresponding measurement results are provided and analyzed to validate their operation. On top of that, theoretical analysis has been done to fully explore the potential of the resulting circuits and systems in the scenario of low-power low-voltage applications.Programa Oficial de Doctorado en TecnologĂas de las Comunicaciones (RD 1393/2007)Komunikazioen Teknologietako Doktoretza Programa Ofiziala (ED 1393/2007
Behavioral Modeling of Mixed-Mode Integrated Circuits
Open Access.-- et al.This work is partially supported by CONACyT through the grant for the sabbatical stay of the first author at University of California at Riverside, during 2009-2010. The authors acknowledge the support from UC-MEXUS-CONACYT collaboration grant CN-09-310; by Promep MĂ©xico under the project UATLX-PTC-088, and by Consejeria de Innovacion Ciencia y Empresa, Junta de Andalucia, Spain, under the project number TIC-2532. The third author thanks the support of the JAE-Doc program of CSIC, co-funded by FSE.Peer Reviewe
Synthesis and monolithic integration of analogue signal processing networks
Data traffic of future 5G telecommunication systems is projected to increase 10 000-fold compared to current rates. 5G fronthaul links are therefore expected to operate in the mm-wave spectrum with some preliminary International Telecommunication Union specifications set for the 71-76 and 81-86 GHz bands. Processing 5 GHz as a single contiguous band in real-time, using existing digital signal processing (DSP) systems, is exceedingly challenging. A similar challenge exists in radio astronomy, with the Square Kilometer Array project expecting data throughput rates of 15 Tbits/s at its completion. Speed improvements on existing state-of-the-art DSPs of 2-3 orders of magnitude are therefore required to meet future demands.
One possible mitigating approach to processing wideband data in real-time is to replace some DSP blocks with analog signal processing (ASP) equivalents, since analogue devices outperform their digital counterparts in terms of cost, power consumption and the maximum attainable bandwidth. The fundamental building block of any ASP is an all-pass network of prescribed response, which can always be synthesized by cascaded first- and second-order all-pass sections (with two cascaded first-order sections being a special case of the latter). The monolithic integration of all-pass networks in commercial CMOS and BiCMOS technology nodes is a key consideration for commercial adaptation of ASPs, since it supports mass production at reduced costs and operating power requirements, making the ASP approach feasible. However, this integration has presented a number of yet unsolved challenges.
Firstly, the state-of-the-art methods for synthesizing quasi-arbitrary group delay functions using all-pass elements lack a theoretical synthesis procedure that guarantees minimum-order networks. In this work an analytically-based solution to the synthesis problem is presented that produces an all-pass network with a response approximating the required group delay to within an arbitrary minimax error. This method is shown to work for any physical realization of second-order all-pass elements, is guaranteed to converge to a global optimum solution without any choice of seed values as an input, and allows synthesis of pre-defined networks described either analytically or numerically.
Secondly, second-order all-pass networks are currently primarily implemented in off-chip planar media, which is unsuited for high volume production. Component sensitivity, process tolerances and on-chip parasitics often make proposed on-chip designs impractical. Consequently, to date, no measured results of a dispersive on-chip second-order all-pass network suitable for ASP applications (delay Q-value (QD) larger than 1) have been presented in either CMOS or BiCMOS technology nodes. In this work, the first ever on-chip CMOS second-order all-pass network is proposed with a measured QD-value larger than 1. Measurements indicate a post-tuning bandwidth of 280 MHz, peak-to-nominal delay variation of 10 ns, QD-value of 1.15 and magnitude variation of 3.1 dB. An active on-chip mm-wave second-order all-pass network is further demonstrated in a 130 nm SiGe BiCMOS technology node with a bandwidth of 40 GHz, peak-to-nominal delay of 62 ps, QD-value of 3.6 and a magnitude ripple of 1.4 dB. This is the first time that measurement results of a mm-wave bandwidth second-order all-pass network have been reported.
This work therefore presents the first step to monolithically integrating ASP solutions to conventional DSP problems, thereby enabling ultra-wideband signal processing on-chip in commercial technology nodes.Thesis (PhD)--University of Pretoria, 2018.Square Kilometer Array (SKA) project - postgraduate scholarshipElectrical, Electronic and Computer EngineeringPhDUnrestricte
Realization of Integrable Low- Voltage Companding Filters for Portable System Applications
Undoubtedly, todayâs integrated electronic systems owe their remarkable performance
primarily to the rapid advancements of digital technology since 1970s. The various
important advantages of digital circuits are: its abstraction from the physical details of
the actual circuit implementation, its comparative insensitiveness to variations in the
manufacturing process, and the operating conditions besides allowing functional
complexity that would not be possible using analog technology. As a result, digital
circuits usually offer a more robust behaviour than their analog counterparts, though
often with area, power and speed drawbacks. Due to these and other benefits, analog
functionality has increasingly been replaced by digital implementations.
In spite of the advantages discussed above, analog components are far from
obsolete and continue to be key components of modern electronic systems. There is
a definite trend toward persistent and ubiquitous use of analog electronic circuits in
day-to-day life. Portable electronic gadgets, wireless communications and the
widespread application of RF tags are just a few examples of contemporary
developments. While all of these electronic systems are based on digital circuitry,
they heavily rely on analog components as interfaces to the real world. In fact, many
modern designs combine powerful digital systems and complementary analog
components on a single chip for cost and reliability reasons. Unfortunately, the design
of such systems-on-chip (SOC) suffers from the vastly different design styles of
analog and digital components. While mature synthesis tools are readily available for
digital designs, there is hardly any such support for analog designers apart from wellestablished
PSPICE-like circuit simulators. Consequently, though the analog part
usually occupies only a small fraction of the entire die area of an SOC, but its design
often constitutes a major bottleneck within the entire development process.
Integrated continuous-time active filters are the class of continuous-time or
analog circuits which are used in various applications like channel selection in radios,
anti-aliasing before sampling, and hearing aids etc. One of the figures of merit of a
filter is the dynamic range; this is the ratio of the largest to the smallest signal that can
be applied at the input of the filter while maintaining certain specified performance.
The dynamic range required in the filter varies with the application and is decided by
the variation in strength of the desired signal as well as that of unwanted signals that are to be rejected by the filter. It is well known that the power dissipation and the
capacitor area of an integrated active filter increases in proportion to its dynamic
range. This situation is incompatible with the needs of integrated systems, especially
battery operated ones. In addition to this fundamental dependence of power dissipation
on dynamic range, the design of integrated active filters is further complicated by the
reduction of supply voltage of integrated circuits imposed by the scaling down of
technologies to attain twin objective of higher speed and lower power consumption in
digital circuits. The reduction in power consumption with decreasing supply voltage
does not apply to analog circuits. In fact, considerable innovation is required with a
reduced supply voltage even to avoid increasing power consumption for a given signal
to noise ratio (S/N). These aspects pose a great hurdle to the active filter designer.
A technique which has attracted the attention of circuit designers as a possible
route to filters with higher dynamic range per unit power consumption is
âcompandingâ. Companding (compression-expansion) filters are a very promising
subclass of continuous-time analog filters, where the input (linear) signal is initially
compressed before it will be handled by the core (non-linear) system. In order to
preserve the linear operation of the whole system, the non-linear signal produced by
the core system is converted back to a linear output signal by employing an
appropriate output stage. The required compression and expansion operations are
performed by employing bipolar transistors in active region or MOS transistors in
weak inversion; the systems thus derived are known as logarithmic-domain (logdomain)
systems. In case MOS transistors operated in saturation region are employed,
the derived structures are known as Square-root domain systems. Finally, the third
class of companding filters can also be obtained by employing bipolar transistors in
active region or MOS transistors in weak inversion; the derived systems are known as
Sinh-domain systems. During the last several years, a significant research effort has been already
carried out in the area of companding circuits. This is due to the fact that their main
advantages are the capability for operation in low-voltage environment and large
dynamic range originated from their companding nature, electronic tunability of the
frequency characteristics, absence of resistors and the potential for operations in varied
frequency regions.Thus, it is obvious that companding filters can be employed for implementing
high-performance analog signal processing in diverse frequency ranges. For example,
companding filters could be used for realizing subsystems in: xDSL modems, disk
drive read channels, biomedical electronics, Bluetooth/ZigBee applications, phaselocked
loops, FM stereo demodulator, touch-tone telephone tone decoder and
crossover network used in a three-way high-fidelity loudspeaker etc.
A number of design methods for companding filters and their building blocks
have been introduced in the literature. Most of the proposed filter structures operate
either above 1.5V or under symmetrical (1.5V) power supplies. According to data that
provides information about the near future of semiconductor technology, International
Technology Roadmap for Semiconductors (ITRS), in 2013, the supply voltage of digital
circuits in 32 nm technology will be 0.5 V. Therefore, the trend for the implementation of
analog integrated circuits is the usage of low-voltage building blocks that use a single
0.5-1.5V power supply.
Therefore, the present investigation was primarily concerned with the study and
design of low voltage and low power Companding filters. The work includes the
study about: the building blocks required in implementing low voltage and low power
Companding filters; the techniques used to realize low voltage and low power
Companding filters and their various areas of application.
Various novel low voltage and low power Companding filter designs have been
developed and studied for their characteristics to be applied in a particular portable
area of application. The developed designs include the N-th order universal
Companding filter designs, which have been reported first time in the open literature.
Further, an endeavor has been made to design Companding filters with orthogonal
tuning of performance parameters so that the designs can be simultaneously used for
various features. The salient features of each of the developed circuit are described.
Electronic tunability is one of the major features of all of the designs. Use of
grounded capacitors and resistorless designs in all the cases makes the designs suitable
for IC technology. All the designs operate in a low-voltage and low-power
environment essential for portable system applications.
Unless specified otherwise, all the investigations on these designs are based on the
PSPICE simulations using model parameters of the NR100N bipolar transistors and BSIM 0.35ÎŒm/TSMC 0.25ÎŒm /TSMC 0.18ÎŒm CMOS process MOS transistors. The
performance of each circuit has been validated by comparing the characteristics
obtained using simulation with the results present in the open literature.
The proposed designs could not be realized in silicon due to non-availability of
foundry facility at the place of study. An effort has already been started to realize
some of the designs in silicon and check their applicability in practical circuits. At the
basic level, one of the proposed Companding filter designs was implemented using the
commercially available transistor array ICs (LM3046N) and was found to verify the
theoretical predictions obtained from the simulation results
Polarization Sensor Design for Biomedical Applications
Advances in fabrication technology have enabled the development of compact, rigid polarization image sensors by integrating pixelated polarization filters with standard image sensing arrays. These compact sensors have the capability for allowing new applications across a variety of disciplines, however their design and use may be influenced by many factors. The underlying image sensor, the pixelated polarization filters, and the incident lighting conditions all directly impact how the sensor performs.
In this research endeavor, I illustrate how a complete understanding of these factors can lead to both new technologies and applications in polarization sensing. To investigate the performance of the underlying image sensor, I present a new CMOS image sensor architecture with a pixel capable of operation using either measured voltages or currents. I show a detailed noise analysis of both modes, and that, as designed, voltage mode operates with lower noise than current mode. Further, I integrated aluminum nanowires with this sensor post fabrication, realizing the design of a compact CMOS sensor with polarization sensitivity. I describe a full set of experiments designed as a benchmark to evaluate the performance of compact, integrated polarization sensors. I use these tests to evaluate for incident intensity, wavelength, focus, and polarization state, demonstrating the accuracy and limitations of polarization measurements with such a compact sensor. Using these as guides, I present two novel biomedical applications that rely on the compact, real-time nature of compact integrated polarimeters. I first demonstrate how these sensors can be used to measure the dynamics of soft tissue in real-time, with no moving parts or complex optical alignment. I used a 2 megapixel integrated polarization sensor to measure the direction and strength of alignment in a bovine flexor tendon at over 20 frames per second, with results that match the current method of rotating polarizers. Secondly, I present a new technique for optical neural recording that uses intrinsic polarization reflectance and requires no fluorescent dyes or electrodes. Exposing the antennal lobe of the locust Schistocerca americana, I was able to measure a change in the polarization reflectance during the introduction of the odors hexanol and octanol with the integrated CMOS polarization sensor
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A high-performance, multi-frequency micro-controlled Electrical Impedance Mammography (EIM) excitation and phantom validation system
The research concentrates on the design, development and calibration of a high performance Electrical Impedance Mammography (EIM) system for early detection of breast cancer at the macro and micro scale (at an early stage applicable for different breast sizes and shapes). The enhancement of the Electrical Impedance Tomography (EIT) system focuses on developing electrical and electronic instrumentations and improving the current source topologies to make them operate at multiple frequencies for the purpose of measuring permittivity and conductivity of different breast tissues. The calibration, assessment systems have employed current calibration in the EIT to evaluate the impedance distribution. This facilitates the acquisition of accurate impedance images to enable images of the internal structure of the breast to be constructed. A constraint on EIT systems is that the current injection system suffers from the effects of stray capacitance having a major impact on the hardware subsystem as the EIT is an ill-posed inverse problem which depends on the noise level in EIT measured data and regularization parameter in the reconstruction algorithm. This research aims are to prevent this problem by using a capacitance cancellation method based on a General Impedance Converter (GIC) implemented by operation of a second generation of current conveyor called OCCII-GIC and calibration methods to facilitate operation in the high frequency range. An EIT system based on a planar 85-electrode channel and using a Microcontroller unit (MCU) for addressing control between 85 electrodes and implementing calibration methods has been constructed. In EIT systems, assessment, validation of the performance and calibration of systematic errors in the electrical field generated inside of the interrogated volume is important. Evaluation of the EIT system will be assessed using a realistic electronic phantom (E-phantom). This enables the evaluation of the different conductivity values of the tissue, which has been created and evaluated based on the RSC circuit model for the different electrical conductivities and electrical impedivities in breast tissue
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