Tejmal S. Rathore

Matrix Approach: Better than Applying Miller’s Equivalents

Abstract The matrix approach is extremely simple and systematic compared to the Miller’s equivalent approach. It is a general approach and the conventional loop and node methods are special cases when there are no controlled sources. It explains how a reciprocal network is converted into a non-reciprocal one due to the presence of controlled sources. It not only gives the exact values for forward gain and input admittance but also gives exact values for reverse gain and output admittance without taking any special precaution.

Digital Measurement of Quality and Dissipation Factors Using Voltage Ratio Meter

ABSTRACT Conventional Hay and Schering bridges for the measurement of quality and dissipation factors respectively are reviewed. They require calibrated decade boxes which are costly. After the bridge is balanced manual calculations are carried out to evaluate the two factors. In the proposed modified method these drawbacks are removed and the accuracy of measurement is enhanced using digital voltage ratio meter. The method allows the uncalibrated elements which are cheaper than the calibrated ones. Manual calculations are totally eliminated. The accuracy and resolution are improved not only because of the digital display but also due to the amplification of one of the voltages that appears in the ratio.

Miller Equivalents and Their Applications

Miller’s theorems are utilized for approximate as well as exact analysis of both passive and active networks in conjunction with other theorems on a single element or different elements in succession. In this paper, all the four possible Miller equivalents are fully exploited for the exact analysis by applying on different elements simultaneously. This has never been attempted before and may be viewed as an alternate approach for analyzing the networks. The four Miller equivalents are derived using the substitution theorem followed by typical illustrative examples.

A New Fast Radix-2 Decimation-in-Frequency Algorithm for Computing the Discrete Hartley Transform

The radix-2 decimation-in-time fast Hartley transform algorithm for computing the Discrete Hartley Transform (DHT) was introduced by Bracewell. A radix-2 decimation-in-frequency algorithm by Meckelburg and Lipka followed. Prado came up with an in-place version of Bracewells decimation-in-time fast Hartley transform algorithm. A set of fast algorithms for both decimation-in-time and decimation-in-frequency was further developed by Sorenson et al. A new fast radix-2 decimation-in-frequency algorithm for computing the DHT that requires less number of multiplications than those presented by Bracewell, Meckelburg and Lipka, Prado and Sorenson et al is proposed. It exploits the characteristics of the DHT matrix, exhibits stage structures with butterflies similar for each stage and introduces multiplying structures in the signal flow diagram. The operation count for the proposed algorithm is determined. It is verified by implementing the program in C.

Minimal Realizations of Logic Functions Using Truth Table Method with Distributed Simplification

ABSTRACT In the conventional method, a truth table (TT) is prepared from the specified logic function. Then it is expressed as the sum of min terms corresponding to the rows in which 1 appears. Finally, this function is further reduced using the Boolean identities. Thus, all the simplifications are concentrated at one place after the TT. This procedure does not always lead to the minimal realization. This paper deals with the minimal realization of logic function using TT in which TT is reduced successively by one variable at a time till all the variables are exhausted. The simplification is carried out, instead at the end of the truth table, at the end of each step of TT reduction. The method is shown to be systematic, and definitely leads to the minimal function. It is simpler in operation than that based on only Boolean identities, Karnaugh map and Quine-McClusky methods, and can handle any number of variables. It is explained with several examples. It is worth introducing as an improvement over the classical TT method in class room teaching.

Analysis of a typical 3-phase star-connected circuit: A phasor diagram approach

Analysis of a typical 3-phase star connected circuit through locus of the tip of any one of the phase voltages is given. Some very interesting properties are proved. With different values of the circuit elements, the circuit becomes voltage to current converter, current to voltage converter, voltage to voltage converter, current to current converter, constant input current circuits and a circuit that maintains output power within certain range over a range of load resistance. In some cases, the circuits are 3-phase circuits while in some cases they are single source circuits. Single source circuits considered by Paice and Dutta Roy are the special cases of these circuits.

Forward and reverse conversions of multi-valued logic numbers

A simple method for converting binary number to any other m-nary (m = 2k, k is an integer > 1) number is outlined. Reverse conversion from the m-nary to the original binary number which is extremely simple is also outlined. Finally, forward and reverse conversions allow converting the numbers from radix rK to radix rk, K and k are integers. These conversions are also applicable to signed numbers. The method is illustrated with several examples. Architectures for converting binary number to quaternary number which can easily be extended to higher order radices is proposed. With the help of this architecture, the method is experimentally verified.

A systematic map method for realizing minimal logic functions of arbitrary number of variables

A map method for reducing a logic function to its minimal form is presented. The function of N variables is first mapped into an m× n map such that m + n = N. Next the map size is reduced by 50% rows or columns by eliminating one of the variables at a time vertically or horizontally. The procedure is repeated till the size of the map becomes 1×1. Because of the inbuilt simplification of logic expressions, the resulting function is minimal. The method is systematic and definitely leads to the minimal function. It is simpler in operation than that based on only Boolean identities, Karnaugh map and Quine-McCluskey methods. It can handle any number of variables. It is explained with several examples.

VLSI design of active filters

A good biquad filter, from practical point of view, should be capable of controlling the poles and zeros independently. In other words, it should be able to control pole frequency and pole Q and the type of generic filter independently. This calls for the control over the numerator and denominator coefficients by independent elements. Such circuits can then be programmed digitally. From economic fabrication point of view the biquad should use as small silicon area on the chip as possible. This is possible by reducing the total capacitance and/or resistance and number of OAs and time-multiplexing the components. The aim of this paper is to present two such biquads which meet the above requirements.

Thevenin Equivalents of Some Interesting Networks with Dependent Sources

ABSTRACT This paper presents two classes of networks whose Thevenin equivalents are interesting. One class of networks is without any independent source. The other class has loop or node method-based delta 0. If proper care is not taken, then their Thevenin equivalent resistances may result in indeterminate forms. A method, which not only leads the correct value instead of such indeterminate forms but also is efficient, is proposed. It is illustrated with two examples.