Comment on “Floating inductance simulation based on currentconveyors”

For the original article see ibid., vol. 33, p. 1748-49 (1997). This comment relates to the aforementioned Letter which presents a floating inductance simulation circuit. The proposed circuit uses four plus-type second-generation current-conveyors (CCII+), two floating resistors and one grounded capacitor. It is shown here that such a realisation is a special case of three already published circuits for floating inductance realisation     

Variable toroidal ferrite phase shifter

Careful design of the magnetic bias circuit used in ferrite phase shifters can help to reduce space, weight and energy consumption. Low reluctance circuits must avoid air-gaps and this can be achieved using toroidal-shaped ferrite inserts positioned inside a rectangular waveguide. Here, these ferrite inserts are fabricated using a viscous plastic processing method that avoids machining and produces a continuous magnetic circuit. Finite-element methods are used to initially model the magnetostatic solution for the bias circuit before being used to analyse the microwave performance of a double toroid phase shifter. A closedform technique is introduced to model the dielectric slab waveguide impedance transformer. The final insertion loss was ,1 dB over the 9.5?10.3 GHz band and return loss of 20 dB was achievable. The phase shift calculation agrees to within 10% of the measured values.     

Modelling current/voltage characteristics of space-charge-limitedcurrents with nonlinear velocity-field relationships

A simple empirical equation is presented to describe the current/voltage characteristic of space-charge-limited currents in semiconductor materials with a nonlinear velocity-field relationship. The equation covers the entire current/voltage characteristic and yields asymptotic behaviour in good agreement with previously published results     

New single-parameter models for electronic circuits with even symmetry nonlinearity

In this paper single-parameter models are presented for the instantaneous characteristics of electronic circuits/systems exhibiting even-symmetry nonlinearities. The models can easily provide closed-form expressions, in terms of the ordinary Bessel functions, for the amplitudes of the second-harmonic and second-order intermodulation components at the output of the nonlinear circuit/system excited by a multisinusoidal input signal. Moreover, by combining the proposed models with the previously published models for instantaneous characteristics exhibiting odd-symmetry nonlinearities, a new method and apparatus are proposed for characterizing nonlinear circuits/systems exhibiting both even- and odd-symmetry nonlinearities. The proposed method and apparatus use the amplitudes of the measured output second- and third-order intermodulation components resulting from a two-tone equal-amplitude input signal.     

Performance analysis and comparison of multi-level hard limiters

A general formula, using a Fourier sine-series representation, is derived for the input–output characteristic of multilevel hard limiters (MHLs) with unequal output jumps occurring at unequally spaced inputs. Using this formula, closed-form expressions involving ordinary Bessel functions are obtained for the harmonic and intermodulation performance of MHLs excited by multisinusoidal inputs with arbitrary amplitudes. The results show that, compared to the ideal hard limiter, MHLs can result in a reduction in the relative third harmonic distortion of about 40 dB, and a reduction in relative third-order intermodulation distortion of about 19 dB depending on the amplitude of the input sinusoids and the shape of the MHL characteristic. Using the proposed model it is possible to generate a database for the harmonic and intermodulation performance of any MHL with arbitrary values of jumps and their locations. Simulation results obtained using the harmonic balance simulator controller in the advanced design system design automation software confirm the accuracy of the proposed technique.     

Effect of Electromagnetic Interference (EMI) on the DC Shift,Harmonic and Intermodulation Performance of Diode-Connected NMOSFET

In this paper a new approximation is presented for the nonlinear relationship between the gate-to-source voltage and the current of a diode-connected NMOSFET. Using this expression closed-form expressions are obtained for the DC and the amplitudes of the fundamental, second- and third-harmonic and intermodulation components of the gate-to-source voltage resulting from exciting the diode-connected NMOSFET by a DC biasing current plus a superimposed multisinusoidal EMI. Comparison between calculated and simulated results is included.