Electrical impedance

About: Electrical impedance is a research topic. Over the lifetime, 36015 publications have been published within this topic receiving 371891 citations. The topic is also known as: electrical impedance & complex impedance.

Inherently impedance matched multiple integrated circuit module

Abstract: A multichip module (MCM) is formed with external connections on coaxial pins. This provides an impedance between a ground connection and a signal connection which is substantially equal per unit length. The module may be configured so that the impedances of the connections between the signal connections and integrated circuit may also be optimally impedance matched.

Input impedance of microstrip antennas

Abstract: Using Richmond's reaction integral equation, an expression is derived for the input impedance of microstrip patch antennas excited by either a microstrip line or a coaxial probe. The effects of the finite substrate thickness, a dielectric protective cover, and associated surface waves are properly included by the use of the exact dyadic Green's function. Using the present formulation the input impedance of a rectangular microstrip antenna is determined and compared with experimental and earlier calculated results.

Large-Signal Transient Response of Junction Transistors

Abstract: Transient response in the active region for junction transistors can be calculated from the conventional small-signal equivalent circuit. This small-signal characterization is adequate to calculate turn-on time and decay time. Carrier storage time, or time for the transistor operating point to move from the current saturation region to the active region, is calculated from a small-signal characterization of the transistor in the current saturation region. Frequency cutoff of alpha, ?N (radians/second) is the most important single transistor parameter affecting switching speed. It is possible with moderate driving current to switch the operating point from collector current cutoff to collector current saturation in times of the order of 3/?N. To switch from collector current saturation to collector current cutoff, in times of the order of 3/?N, carrier storage effects must be avoided.

Reevaluation of Performance of Electric Double-layer Capacitors from Constant-current Charge/Discharge and Cyclic Voltammetry

Abstract: The electric characteristics of electric-double layer capacitors (EDLCs) are determined by their capacitance which is usually measured in the time domain from constant-current charging/discharging and cyclic voltammetry tests, and from the frequency domain using nonlinear least-squares fitting of spectral impedance. The time-voltage and current-voltage profiles from the first two techniques are commonly treated by assuming ideal RsC behavior in spite of the nonlinear response of the device, which in turn provides inaccurate values for its characteristic metrics [corrected]. In this paper we revisit the calculation of capacitance, power and energy of EDLCs from the time domain constant-current step response and linear voltage waveform, under the assumption that the device behaves as an equivalent fractional-order circuit consisting of a resistance Rs in series with a constant phase element (CPE(Q, α), with Q being a pseudocapacitance and α a dispersion coefficient). In particular, we show with the derived (Rs, Q, α)-based expressions, that the corresponding nonlinear effects in voltage-time and current-voltage can be encompassed through nonlinear terms function of the coefficient α, which is not possible with the classical RsC model. We validate our formulae with the experimental measurements of different EDLCs.

Method and apparatus for apical detection with complex impedance measurement

Abstract: An apical position detector (40) for use in dental endodontics includes an electronic controller (42) coupled to a conductive probe (46) and a lip electrode (48) The probe (46) is positioned in a root canal (60) and the lip electrode contacts another location on the patient's body The controller (46) produces a test signal as a combination of signals at selected frequencies The controller (46) then monitors a voltage of the probe (46) and extracts the amplitude and phase of each of the frequency components of the voltage at the probe (46) Test scores are generated from summations of the amplitudes and/or phases of the various frequency components to determine when the impedance between the probe (46) and the lip electrode (48) changes from a primarily reactive impedance to a primarily resistive impedance A first test score is displayed to indicate when the impedance changes from a reactive to a resistive impedance The second test score indicates when the measurement conditions are unsatisfactory The test scores are displayed in bar graph or similar form