Showing papers in "Electronics Letters in 1967"
TL;DR: In this article, a method to earth all capacitors, by replacing them with earthed gyrator-capacitor combinations, is described, which is easier to obtain earthed capacitors than unearthed ones in integrated circuits.
Abstract: Fabrication techniques indicate that it is easier to obtain earthed capacitors than unearthed ones in integrated circuits. To take advantage of these techniques, a method to earth all capacitors, by replacing them with earthed gyrator-capacitor combinations, is described here.
435 citations
TL;DR: In this article, a novel circuit for the simulation of high-quality inductors is described, based on differential amplifiers and can use standard integrated circuits; in initial tests, it has given very large effective inductances with high Qfactors at very low frequencies.
Abstract: A novel circuit for the simulation of high-quality inductors is described. The circuit is based on differential amplifiers and can use standard integrated circuits; in initial tests, it has given very large effective inductances with high Qfactors at very low frequencies.
185 citations
TL;DR: In this paper, an ideal negative-impedance invertor (Lundry type) using a voltage-controlled voltage source is described, and illustrated by a practical circuit using an operational amplifier.
Abstract: An ideal negative-impedance invertor (Lundry type) using a voltage-controlled voltage source is described, and is illustrated by a practical circuit using an operational amplifier. It is used in conjunction with negative-impedance convertors to realise new gyrator circuits.
80 citations
TL;DR: In this paper, positive-immittance convertors (p.i.c.s) with a purely reactive conversion ratio are used to simulate inductors in LCnetworks, which results in simulated inductors whose magnitudes are controlled by resistor networks.
Abstract: Positive-immittance convertors (p.i.c.s) with a purely reactive conversion ratio are used to simulate inductors in LCnetworks. This approach, in addition to all the advantages and disadvantages of multigyrator-capacitor networks, results in simulated inductors whose magnitudes are controlled by resistor networks. Consequently the capacitors directly involved in the simulation of the inductors may all be made equal to some convenient magnitude.
64 citations
TL;DR: In this article, it is predicted that for a given operating frequency, there exist certain plasma densities for which the system is resonant, and this very strongly enhanced radiation is fully confirmed by experiments.
Abstract: The plasma sheath existing between an antenna ana a surrounding plasma layer plays an essential role. It is predicted that, for a given operating frequency, there exist certain plasma densities for which the system is resonant, and this very strongly enhanced radiation is fully confirmed by experiments.
52 citations
TL;DR: In this paper, an application of Thevenin's equivalent circuit for multiple parallel transmission lines to the time-domain analysis of wave propagation over such lines is presented, where a system of two coupled transmission lines is treated.
Abstract: Thevenin's equivalent circuit for a single transmission line is well known. The letter presents an application of Thevenin's equivalent circuit for multiple parallel transmission lines to the time-domain analysis of wave propagation over such lines. For purposes of illustration, a system of two coupled transmission lines is treated.
44 citations
TL;DR: In this paper, transformations to convert lowpass systems to highpass, bandpass and band-elimination systems in the case of pulse transfer functions of digital filters are given.
Abstract: Transformations to convert lowpass systems to highpass, bandpass and band-elimination systems in the case of pulse transfer functions of digital filters are given in this paper. It is believed that these results, for z plane transformations, are the first ones to be published in this field.
32 citations
TL;DR: In this paper, the feasibility of constructing waveguides and directional couplers is demonstrated experimentally, and some theoretical considerations referring to waveguiders are presented, but the feasibility is not discussed.
Abstract: In realising microwave-circuit functions using surface technology, the physical size of passive components using e.m. waves imposes a limitation. This letter investigates the application of acoustic waves to this case. The feasibility of constructing waveguides and directional couplers is demonstrated experimentally, and some theoretical considerations referring to waveguides are presented.
26 citations
TL;DR: In this article, the appearance of pairs of complex waves is discussed for an open waveguiding structure, and the absence of losses in the system requires the simultaneous presence of two complex waves, the wavenumbers of which possess symmetry properties of the conjugate type.
Abstract: The appearance in pairs of complex waves is discussed for an open waveguiding structure. It is shown that the absence of losses in the system requires the simultaneous presence of two complex waves, the wavenumbers of which possess symmetry properties of the conjugate type. These properties still hold if radiation losses occur, and the symmetry disappears only if conduction losses are introduced.
24 citations
TL;DR: In this paper, an alternative circuit is proposed which avoids this matching problem and can be used with most existing gyrators, but it requires very close matching of the gyrator.
Abstract: Transistorised gyrator circuits that have been developed to date are grounded 2-port devices that can directly simulate only grounded inductances. To obtain floating inductances, it has been suggested that two such gyrators might be used, but the scheme requires very close matching of the gyrators. An alternative circuit is proposed which avoids this matching problem and can be used with most existing gyrators.
24 citations
TL;DR: In this paper, a theorem on (m+1) terminal resistive networks was proved, and it was shown that the restrictions on the n×n open-circuit-impedance matrix Z of a resistive n port based on m+1 terminals are at the most quadratic in entries Zpq of Z.
Abstract: A theorem on (m+1) terminal resistive networks is stated. As a consequence, an (m+1)terminal network may be considered an m dimensional, strongly Ptolemaic metric space. Furthermore, the restrictions on the n×n open-circuit-impedance matrix Z of a resistive n port based on m+1 terminals, are at the most quadratic in entries Zpq of Z.
TL;DR: An integratable high-performance direct-coupled gyrator circuit which is capable of being used in the simulation of floating inductors for lowpass filters is presented, and some of the peculiarities of practical floating gyrators are discussed as discussed by the authors.
Abstract: An integratable high-performance direct-coupled gyrator circuit which is capable of being used in the simulation of floating inductors for lowpass filters is presented, and some of the peculiarities of practical floating gyrators are discussed.
TL;DR: In this paper, a simple theory of a possible f.m. noise source peculiar to Gunn-effect oscillators is presented and compared with experimental data, showing that the spectrum of cavity-controlled oscillators has an F1 noise power considerably greater than the a.m noise power.
Abstract: The spectrum of Gunn-effect cavity-controlled oscillators has an f.m. noise power considerably greater than the a.m. noise power. A simple theory of a possible f.m. noise source peculiar to Gunn-effect oscillators is presented and compared with experimental data.
TL;DR: In this article, the sensitivity of a 2nd-order Sallen-Key circuit was reduced from 2Q2/μ to 3Q/μ by increasing the closed-loop gain from 1 to 4/3.
Abstract: The sensitivity, to μ−1 (where μ is the open-loop amplifier gain), of the Q factor of a 2nd-order Sallen-Key circuit can be reduced from the conventional value 2Q2/μ to 3Q/μ by increasing the closed-loop gain from 1 to 4/3. However, this increases the sensitivity to passive-element variations. An optimum engineering solution is found by minimising, for given maximum component variations, the resulting variation of Q, rather than the sensitivities. This makes single-amplifier circuits usable for higher Q factors than previously, which is of particular interest for microelectronic realisations of such circuits.
TL;DR: Two new integratable high-performance direct-coupled gyrator circuits are presented, and some aspects of their design are discussed.
Abstract: Two new integratable high-performance direct-coupled gyrator circuits are presented, and some aspects of their design are discussed. Simulated inductances of up to 200H have been realised, with stable Q factors of up to several thousands. Without special compensation, the temperature coefficients were 20×10−6 per deg C for inductance and 800×10−6 per deg C for Q.
TL;DR: Experimental results on gyration resistance, input impedance and resonant-circuit Q factor show excellent agreement with theory.
Abstract: An integrated gyrator is described. The device uses 1 diode, 12 resistors and 9 transistors, two of which are lateral p-n-p. Experimental results on gyration resistance, input impedance and resonant-circuit Q factor show excellent agreement with theory.
TL;DR: Relaxation of the conventional constraint to have the lowest-possible-order curves in an approximation procedure results in redundant functions that will lead to lower-sensitivity networks in RCactive-filter design.
Abstract: Relaxation of the conventional constraint to have the lowest-possible-order curves in an approximation procedure results in redundant functions. These, when realised, will lead to lower-sensitivity networks. This is of special importance in RCactive-filter design.
TL;DR: A simple technique, exploiting a property of pseudorandom binary signals, reduces to zero the effect of linear disturbances in the estimation of a system weighting function by cross-correlation.
Abstract: A simple technique, exploiting a property of pseudorandom binary signals, reduces to zero the effect of linear disturbances in the estimation of a system weighting function by cross-correlation. Errors due to quadratic disturbances are then constant and may be minimised by choice of particular pseudorandom binary signals which are tabulated. The principal remaining error is also constant, and an unbiased estimate of the system weighting function is easily obtained.
TL;DR: In this article, the authors investigated the failure mechanism of planar Gunn diodes and showed that a conducting channel of Sn(In) is responsible for the final catastrophic failure, where excess heat is generated at the anode, where also the breakdown is observed to start.
Abstract: Observations on electrical properties of planar Gunn diodes and on failure mechanisms using Sn–Ag and In–Au contacts are reported. A conducting channel of Sn(In) is proved to be responsible for the final catastrophic failure. Excess heat is generated at the anode, where also the breakdown is observed to start. Mechanisms starting the breakdown (hole injection and combined ion drift and diffusion of impurities) are discussed.
TL;DR: In this article, the frequency against voltage curves of planar planar Gunn diodes with concentric contacts are presented for three different contact geometries, each of them having a tuning range of more than one octave.
Abstract: Voltage tuning of Gunn oscillations in the frequency range 1.5–8.5 GHz has been achieved by using planar Gunn diodes with concentric contacts. Frequency against voltage curves are presented for three diodes with somewhat different contact geometries, each of them having a tuning range of more than one octave. This simple method of tuning over large frequency ranges is of great potential interest. The production process using evaporation and etching is described.
TL;DR: In this paper, the dynamic behaviour of the Gunn diode is described using a dynamic drift-velocity field-strength characteristic which can be derived from a simple domain model, and a more general theory than that given earlier for the efficiency of a GNOD is set up for the mixed resonant transit-time mode and the suppressed resonant mode.
Abstract: The dynamic behaviour of the Gunn diode is described using a dynamic drift-velocity field-strength characteristic which can be derived from a simple domain model. From, this characterisation, a more general theory than that given earlier for the efficiency of a Gunn diode is set up for the mixed resonant transit-time mode and the suppressed resonant mode.
TL;DR: Using Step and linear segment approximations of message waveforms, some asynchronous, pulse-modulation systems have been developed, and their characteristics, e.g. dynamic range, quantising noise and channel-bandwidth requirements, have been determined.
Abstract: Using Step and linear segment approximations of message waveforms, some asynchronous, pulse-modulation systems have been developed. The four important types have been theoretically investigated, and, their characteristics, e.g. dynamic range, quantising noise and channel-bandwidth requirements, have been determined.
TL;DR: In this paper, the authors describe some characteristics of an oscillator based upon the acoustoelectric interaction in piezoelectrics, and make particular reference to frequency modulation and related-device applications.
Abstract: This letter describes some characteristics of an oscillator based upon the acoustoelectric interaction in piezoelectric semiconductors—the acoustoelectric oscillator. Particular reference is made to frequency modulation and to related-device applications.
TL;DR: In this article, the lemma of Lyapunov is generalized for time-varying systems, in which it is shown that additional conditions are required for the lemmas to hold.
Abstract: The lemma of Lyapunov gives the necessary and sufficient condition for the stability of a time-invariant system in terms of the existence of a positive-definite symmetric matrix. In this letter, the lemma is generalised for time-varying systems, in which it is shown that additional conditions are required for the lemma to hold. The conditions involve boundedness of certain quantities and uniform complete observability of a pair of matrixes.
TL;DR: In this article, the current/voltage characteristics of a transistor structure when controlled by space-charge and transit-time effects are described, and it is shown that large negative conductances can be obtained at high frequencies.
Abstract: The letter describes the current/voltage characteristics of a transistor structure when controlled by space-charge and transit-time effects. It is shown that large negative conductances can be obtained at high frequencies. Operation is not limited by transit-time effects, and efficient high-power working at centimetre and millimetre wavelengths should be possible.
TL;DR: In this paper, a direct search procedure is described for obtaining the optimum function, and hence the Lyapunov function of an arbitrary order which gives the best estimate of the region of asymptotic stability.
Abstract: The Zubov and Ingwerson procedures for constructing Lyapunov functions depend upon an initial choice of some function of the state variables. A direct search procedure is described for obtaining the optimum function, and hence the Lyapunov function of an arbitrary order which gives the best estimate of the region of asymptotic stability. The method is illustrated by an example.
TL;DR: In this paper, electron detachment in swarm conditions has been observed in SF6 at an observed theshold of about Elp = 95V/cmtorr at a pressure of 5.2torr.
Abstract: Electron detachment in swarm conditions has been observed in SF6 at an observed theshold of about Elp = 95V/cmtorr at a pressure of 5.2torr. The relevance of this process to various corona studies is discussed briefly.
TL;DR: In this paper, the conditions for minimum attenuation of a wave supported by a coaxial guide and by a parallel-wire transmission line have been investigated experimentally and shown to comply with the earlier theoretical predictions.
Abstract: The conditions for minimum attenuation of this wave supported in one case by a coaxial guide and in another by a parallel-wire transmission line have been investigated experimentally and shown to comply with the earlier theoretical predictions. The best results are obtained by loading one or other of the two supporting surfaces and not both simultaneously.
TL;DR: By using a simple cavity which gives a high rate of change of reactance with frequency, it was shown that the f.m. noise from a Gunn oscillator can be reduced to a much lower level than that reported recently by Faulkner and Meade as discussed by the authors.
Abstract: By using a simple cavity which gives a high rate of change of reactance with frequency, it is shown that the f.m. noise from a Gunn oscillator can be reduced to a much lower level than that reported recently by Faulkner and Meade.
TL;DR: In this article, the use of highmobility piezoelectric semiconductors for acoustic-wave amplification at microwave frequencies is considered, and the authors propose a method to obtain high-mobility PSSs for microwave frequency.
Abstract: The use of high-mobility piezoelectric semiconductors for acoustic-wave amplification at microwave frequencies is considered.