A switched capacitor circuit simulator

Abstract:

This paper describes the modeling and simulation of switched capacitor circuits in AWEswit. AWEswitis a mixed signal simulator for switched capacitor circuits. It allows for portions of the circuit to be modeled with digital blocks controlled by an event queue. The remainder of the circuit is modeled in the analog domain. The paper describes the circuit formulations employed by AWEswit, and how they are exploited in modeling the nonidealities associated with switched capacitor circuits.
AWEswit employs asymptotic waveform evaluation (AWE) as its core simulation engine. It combines circuit formulations in the charge-voltage and current-voltage regimes. This flexibility in the circuit formulations means that if the circuit is modeled entirely with ideal switches (Le., no resistors), then it is automatically solved in the chargevoltage regime (like SWITCAP2). However,
if portions of the circuit need to be solved in the current-voltage regime, then AWEswit automatically partitions the circuit and solves the different partitions in whichever regime is appropriate, i.e., in the current-voltage regime (using AWE to evaluate circuit response) or in the chargevoltage regime. AWEswit naturally handles the bandwidth limitations associated with switched capacitor circuits. In addition, it models the clock feedthrough and signal-dependent charge dump that characterize MOSFET  switches. The simulator is illustrated by example.


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Tunnel-Diode Low-Level Detection

Abstract :

An analysis of tnmel-diode low-level detection is presented for the purpose of explaining some of the unusual detection characteristics that occur under certain hias conditions. For example, in the vicinity of its inflection hias point, a tmmel diode exhibits a discriminator-like rectification behavior with two sensitivity peaks. When biased at one of these peaks, the diode is capable of unusuaUy high sensitivities, at least an order of magnitnde better than the sensitivity of any other known diode. It is shown that these high sensitivities are proportional to (1 J?z),where P is the RF power gain of the detector viewed as a reflection-type amplifier. The resultant gain bandwidth (or sensitivity bandwidth) limitations of the detector are discussed. UnusuaUy high sensitivities are also possible at the lower microwave frequencies when the tunnel diode is biased at its peak current point. A knowledge of the diode static characteristics, the reflection coefficient, and the video circnit permits an accnrate analytical evaluation of the sensitivity performance of any tunnel diode, and calculations are carried out for an example diode and compared against measured data. The paper also contains a speeific comparison of the relative sensitivity performance of the example tnnnel diode versus a hot carrier diode.

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Thermal Analysis of Extruded Aluminum Fin Heat Sink for LED Cooling Application

ABSTRACT :

Light Emitting Diode or LED now is becoming a  popular lighting used at many types of applications. LED becomes more favorable to use than other types of lighting such as fluorescent or even light bulb. This is because LED can provide high lumens with low power electricity and does
not contain any toxic material, such as fluorescent lights having mercury inside which is not good towards the environment.  Advantages of using LED are high luminosity, more energy saving, high lifetime hours, and applicable in many applications. However, LED operating temperature should be considered. LEDs with high power, such as 10 Watts or more, can generate bright lighting, but also will have high operating temperature. This high operating temperature of LED should be lowered, since high operating temperature will lead to reductions of the luminosity and the lifetime of LED.
   Many cooling systems can be used to reduce the operating temperature of LED; a simple one is to use the extruded-fin heat sink. Heat sink is easy to manufacture, relatively low in cost, light in weight, and can become an adequate cooling means with good reliability. The choice of an optimal heat sink dimension depends on the power of heat source.  In this work, 10-Watt LED with the 58 0
C operating temperature was used. The aim for this study was to add extruded-fin heat sink to dissipate heat generated by the LED, with target temperature of LED decreased down to 50 C. Initial experiment was done to check the LED operating temperature and then ANSYS ICEPAK was used for numerical simulation; ANSYS ICEPAK is computational software for the study of thermal management of electronic devices and systems. For the present study, the numerical simulation of LED using extruded-fin as heat sink was  performed. Through numerical simulation accounting for the variations in fin heights, fin thicknesses, fin pitches, and base heights, the optimal dimension of the heat sink was determined to achieve the target temperature of 50 C.


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Vlasov model for the impedance of a rod-pinch diode

The rod-pinch diode[l,2] is a cylindrical, pinched-beam diode being developed as a radiography source[3]. The  diode consists of a small radius anode rod extending through the hole
of an annular cathode. The diode has  been operated at 1 to S MV with an impedance of 20 to SO
Cl, a FWHM pulse width of 20 to SO ns, and an anode  radius as small as 0.25 cm[l-31. The diode is designed to  run at critical current so that electrons emitted fkom the  cathode flow axially along the anode rod and pinch radially onto the rod tip. Typically, ion emission fkom the anode is required for propagation of the pinch along the rod. Without ions, the pinch would occur on the anode rod just downstream of the cathode disk. In order to  assure that a given diode will he properly designed to mn at critical current requires a detailed knowledge of the  diode impedance characteristics. Initially, a laminar flow model[4] was developed to describe the rod-pinch diode. Although this model provides considerable insight into  diode operation, PIC simulations show that the electron
flow is not laminar[2]. The model of [4] was extended to  include transverse electron pressure in order to consider the effects of nonlaminar flow[S]. However, a form for  the transverse pressure tensor is required to close the equation set in this model and only special forms of the  pressure tensor are analytically tractable. Here, a Vlasov model for the diode electron flow is developed using an electron distribution function with properties that are well characterized and directly related to a rod-pinch diode. In  this model, the pressure tensor is self-consistently derived.

LVLASOV MODEL FOR THE  ELECTRON FLOW  

The geometry used in the rod-pinch diode model is illustrated in Fig. 1. Ions are emitted along the entire  length C of the anode rod and flow radially outward while electrons are only emitted from the bottom of the cathode at radius r. and flow axially in a sheath above the anode. The radius of the anode rod is r. and the inner edge of the anode sheath is at re There are two distinct regions; the sheath (rc t r t rJ contains ion and electrons, while the region between the sheath and the anode (rJ t r 2 r,) contains only ions. At z = C, the electrons pinch onto the end of the rod (not shown). Because C >> r,, Udr >> Udz  except at the end of the rod where the pinch occurs.

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Signal Conditioning Based On Programmable Analog Circuits

ABSTRACT: 
Programmable circuits are commonly used class of electronic devices. In practice this term usually refersto microcontrollers with different kind of programmable memories and to programmable logic circuits (PAL, CPLD,FPGA). Most of these devices are digital circuits. Thanks to the huge progress in miniaturization of electronic circuits, the new class of devices – programmable analog circuits – was put on the market. These circuits bring new possibilities to design electronic circuit. One of the most promising fields of application is construction of analog signal conditioning circuits. This paper describes feature and parameters of sample programmable analog circuits. It depicts internal structure and theory of operation of these devices. One of commercially available programmable analog circuits was used in development of signal conditioning block for vibration measurement system.
It works as programmable gain amplifier and low-pass anti-aliasing filter with programmable cut-off frequency. Amplifier transient characteristics for different gain values and frequency response of the filter were measured.

GENERAL INFORMATION 

The common trend among the manufacturers ofelectronic devices is to miniaturize their products. Very often this leads to integration of large number of functional blocks of the device in one small, complex integrated circuit. Small dimensions and weight of the device gives the possibility to use it as a portable apparatus. However, this is not the main and sole objective. Using one, specialized integrated circuit instead of many separate ones gives the opportunity to significantly lower the price of the device when the mass production methods are employed. Moreover, a single integrated circuit will require much less electric energy, therefore it can operate much longer using battery power. An important advantage of the “integrated measurement systems” is the ability to improve the parameters of the constructed devices both in the field of precision (e.g. due to minimisation of  the influence of the environment noise) and of operation speed. Such systems may integrate advanced analog  circuits, signal processor cores and various measurement transducers. It is extremely important for
example for the distributed vibrations measurement system [3, 4], for which it may be possible to mount the measurement modules inside the generator. Manufacturers of the analog integrated circuits have problems manufacturing capacitors, inductors and resistors in the silicon substrate. They take up large amount of space and often turn out to be thermally unstable. Besides, the polysilicon resistors are nonlinear. The solution to these problems are the switched capacitance circuits [6]. They allow to
manufacture complex analog circuits with arbitrary frequency response. The switched capacitance
technique is the basis of the construction of the reprogrammable analog circuits. They are universal circuits for which the user can determine the configuration of the interconnections between internal
elements and set the required values of the passive elements. As a result it is possible to obtain a circuit having virtually any desired functionality and programmatically adjustable parameters (gain, filter frequencies) without any need for external elements.

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Electronic Computing Circuits of ENIAC

Summary-The ENIAC (Electronic Numerical Integrator and Computer), the first electronic computing machine to be built, is a very large device (containing 18,000 vacuum tubes) compounded out of a few basic types of computing circuits. The design principles that were followed in order to insure reliable operation of the electronic computer are presented, and the basic types of computing circuits are analyzed. Most of the design work on component circuits was devoted to constructing reliable memory circuits (ffip-flops) and adding circuits (counters). These are treated in detail. The ENIAC performs the operations of addition, subtraction, multiplication, division, square-rooting, and the looking up of function

values automatically. The units which perform these operations, the units which take numerical data into and out of the machine, and those which control the over-all operation are described. The technique of combining the basic electronic circuits to perform these functions is illustrated by three typical computing circuits: the addition circuit, a programming circuit, and the multiplication circuits

I.              INTRODUCTION

HE ENIAC (Electronic Numerical Integrator and Computer) is the first general-purpose computing machine in which the computation is done entirely electronically. It is the purpose of this paper to discuss the design of the various circuits used and to show how they are combined to make an automatically sequenced electronic computer. As an introduction, however, it is worth while to consider the general question: What is the function of the ENIAC? That is, what kinds of problems does it solve?

Very briefly, the answer to this question is that the ENIAC can solve any problem which can be reduced to numerical computation, i.e., to a finite sequence (of reasonable length) consisting of additions, subtractions, multiplications, divisions, square-rootings, and the looking up of function values. Hence, it can differentiate, integrate, solve systems of imultaneous algebraic and transcendental equations, partial differential equations, etc. The importance of high-speed electronic computation derives from the fact that there are many problems that the mathematical physicist can easily formulate but which can be solved only with great labor. The differential equations of exterior ballistics will serve as a good example of this, especially since the ENIAC was designed primarily to solve total differential equations of about this order of complexity.


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Combinatorics at electronic circuit

Abstract—The field programmable analog array (FPAA) are advantageously useful different functional units, electronic circuits, part of electronic circuit, onto his forming. In this direction there is an opportunity if the cooperation of embedded informatics device and FPAA is possible especially. Perspective that solution, where the electronic circuit to be worked up some-, or more adaptivity plays himself with a partial self-organization in that manner the topology, regarding the parameters of the single elements.

I.                    INTRODUCTION

His automatic solution is old endeavor in the electronics developments for an electronic circuit constructional task. The parametrical description of the electronic circuit topology and the single element belongs into this naturally. A number interactive solution, developer environments stand for a provision, one may not miss the specialist’s intervention, his knowledge however. We recommend a solution, where we raffle components with the method of the raw attempt in our present article, then these we experiment with connecting him throughout. We check the electronic circuit worked up with the combinatorial method using the help of a simulation program. We make this, since the computing capacity stands for our provision limitlessly quasi through modern computers. We wish to repair the efficiency of the method with the suitable algorithmic refinements in the additional ones. This article his writing, the field programme analog array (FPAA) the development of the use of his spreading. [3] [5] [4] II. CIRCUIT DESCRIPTION, CONSTRUCTION The electronic circuit the connection matrices (Kc) are used for a network’s description widespread in a simulation. The network according to the figure 1 it a matrix writes it down equation 1. This matrix has information about the connection between the nodes and its direction. The columns of the matrix contain the branches beginning there end from the single node while the rows write the single branches being attached to junctions down. [2]

Likewise the cited from literature we know that it is a figure 1 and for its graph and its branches an electronic component writes the relation of current tenseness down. The computerized electronic circuit simulation means the calculation of voltages to the single branch of the graph. Widespread, procedures which can be applied well stand onto a provision in this direction.

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