Need For Inductors Research Articles

Monte Carlo analysis of inductor-less wideband amplifier

As more and more applications are being integrated on single chip, the focus of research is being shifted to low cost and better performance wide band amplifiers than the narrow band amplifiers which were suitable for devices having single application. Mostly the wide band amplifiers are designed using inductors so as to overcome the effect of capacitive parasitic but it leads to overshoot and thus resulting in bad frequency response. So there is a need to search for other methods like optimization of the parameters in the circuit that can increase the bandwidth without the need of inductors as it leads to bulky designs and consume a lot of die-space.

A Prospective Randomized Comparison of Defibrillation Efficacy of Truncated Pulses and Damped Sine Wave Pulses in Humans

Damped sine wave pulses have been used for nearly 50 years in transthoracic defibrillation systems. The purpose of this study was to determine whether damped sine wave pulses have a role in implantable defibrillators. In 21 survivors of cardiac arrest, we prospectively compared defibrillation efficacy of a standard truncated capacitor (RC) monophasic pulse with a damped sine wave inductor-capacitor (LRC) pulse using a right ventricular-left ventricular epicardial patch-patch electrode system. The RC pulse was a standard 65% tilt monophasic waveform generated from a 120 mu F capacitor. The LRC pulse was designed to simulate the waveform currently used in transthoracic defibrillators and was generated by passing the charge stored on a 40 mu F capacitor through a 37-mH inductor. Capacitor voltage, peak delivered voltage, peak delivered current, discharge pathway resistance, delivered energy, and stored energy were compared for the two waveforms at the defibrillation threshold. There was no difference in defibrillation efficacy for the two waveforms. Peak delivered voltage was similar at the defibrillation threshold: 313 +/- 101 V for the RC pulse and 342 +/- 119 V for the LRC pulse (P = 0.16). Similarly, no differences were found in defibrillation threshold peak delivered current: 8.6 +/- 2.5 (RC) versus 9.3 +/- 2.7 (LRC) amperes (A) (P = 0.20); discharge pathway resistance: 37 +/- 11 (RC) versus 38 +/- 13 (LRC) omega (P = 0.71); delivered energy: 7.0 +/- 4.5 (RC) versus 7.0 +/- 4.0 (LRC) joules (J) (P = 0.88); and stored energy: 8.7 +/- 5.7 (RC) versus 9.8 +/- 5.4 (LRC) J (P = 0.35). Although both waveforms performed the same, it was necessary to use substantially higher stored voltages with the damped sine wave delivery system than with the truncated waveform delivery system: 356 +/- 110 V for the RC pulse and 675 +/- 192 V for the LRC pulse (P < 0.0001). This study demonstrates that RC monophasic pulses provide equally effective epicardial defibrillation as LRC pulses with respect to delivered voltage and current and stored and delivered energy. However, in order for LRC pulses to provide comparable delivered voltage, current, and energy to that of RC pulses, nearly twice the voltage must be stored on the capacitor to accomplish the same task. These findings suggest that despite the nearly 50-year experience with damped sine wave pulses with transthoracic defibrillators, there is no need to begin using damped sine wave pulses for implantable defibrillators. Moreover, these data raise a question regarding the need for inductors in transthoracic defibrillators.

A new family of active variable equalizers

An active version of the Bode-type variable equalizer has been designed. Variable equalizers are widely used for amplitude equalization in wide-band transmission systems because they possess the unique property that the equalization shape does not change as the amount of equalization is varied. Such a property is especially desirable when equalizing cable of varying length. The active variable equalizer to be described here overcomes many of the disadvantages associated with the conventional passive version, which include the need for inductors, a complex design procedure, and incompatibility with modem electronic control elements. This design also has advantages over other active variable equalizer designs. Such an equalizer is especially applicable to precision equalization at frequencies below 10 MHz. As an example, a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\sqrt{f}</tex> equalizer can be built with a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\pm 9-dB</tex> range having only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\pm 0.05-dB</tex> maximum error. The equalizer is easily built with operational amplifiers and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</tex> networks.

Active R ladders: High frequency, high order, low sensitivity active R filters without external capacitors

Active R filter techniques which make use of the pole of an operational amplifier to produce the state variables without the need for inductors or external capacitors may be employed to simulate all of the elements of both singly and doubly terminated reactance ladders. Although the design techniques are very simple and follow directly from passive synthesis techniques, the resulting filters offer high-order circuits with low sensitivity. However, the primary advantage of these active R filters is the ability to design filters which operate in a considerably higher frequency range than obtainable with standard active RC designs. While still primarily of research interest due to dynamic range problems and temperature sensitivity problems, active R ladders may be adequately compensated to allow many applications in specialized signal processing environments.

New Approaches To the Design of Active Filters

Operational amplifiers can greatly simplify the design of high performance signal filters because they elimi nate the need for inductors and for impedance matching. Furthermore, use of active filters can result in reduc tion of weight, size, and cost. Filters designed to satisfy sophisticated mathematical criteria can be realized without resort to "equalization" or trimming. In this issue we discuss the design of operational amplifier and analog computer circuits suitable for use as low pass filters. We also discuss the commonly used mathematically designed filters, i.e. Butterworth, Chebyshev, and Bessel. In addition, we present two new types of theoretical filters, the Paynter and the Aver aging filters. Design data necessary for realizing these theoretical filters with amplifier circuits is provided. In the next issue we shall discuss the design of band pass, band reject, high pass and all pass active filter circuits.