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.

Electrical properties of RF sputtering systems

Abstract: A theory is developed that gives a relatively complete electrical characterization of rf sputtering systems. Three types of systems are analyzed: tuned substrate, driven substrate, and controlled area ratio of electrode (CARE) systems. The theory is applicable to any of these systems that do not use magnetic fields to confine the plasma. Given the input rf power and voltage at the target, and any other parameters that can be specified as independent variables (e.g., pressure, substrate drive voltage, tuning impedance, and system geometry), the theory provides explicit values for all dc and rf electrical parameters of the system. The dc bias developed ut the substrate is explained and related to the resputtering energy. In addition, an approximate calculation is presented for the ion density in the plasma; this calculation allows a semiquantitative estimate of the rf voltage developed at the target for a given value of rf input power. It also shows the influence of pressure and frequency on rf sputtering system operation. Comparisons are made with real rf sputtering systems; these show that the theory is quite successful in predicting the operation of these systems. In addition, a much better understanding is achieved of some of the complex electrical phenomena encountered in these systems. The theory should prove useful both for new system design and for diagnostic work on existing equipment.

A Three-Section Dual-Band Transformer for Frequency-Dependent Complex Load Impedance

Abstract: In this letter, we propose a practical three-section dual-band transformer, which can terminate frequency-dependent complex load impedance at two arbitrary bands simultaneously. Analytical equations are derived to achieve the exact closed-form solutions. Numerical examples are examined to verify the validity. This three-section transformer can be utilized to match the complex load impedance with unequal values at two different frequencies, such as microwave amplifiers based on transistors, mixers, various kinds of antennas, and so forth.

Effective Radii of On-Chip Decoupling Capacitors

Abstract: Decoupling capacitors are widely used to reduce power supply noise. On-chip decoupling capacitors have traditionally been allocated into the white space available on a die or placed inside the rows in standard cell circuit blocks. The efficacy of on-chip decoupling capacitors depends upon the impedance of the power/ground lines connecting the capacitors to the current loads and power supplies. A design methodology for placing on-chip decoupling capacitors is presented in this paper. A maximum effective radius is shown to exist for each on-chip decoupling capacitor. Beyond this effective distance, a decoupling capacitor is ineffective. Depending upon the parasitic impedance of the power distribution system, the maximum voltage drop seen at the current load is caused either by the first droop (determined by the rise time) or by the second droop (determined by the transition time). Two criteria to estimate the minimum required on-chip decoupling capacitance are developed based on the critical parasitic impedance. In order to provide the required charge drawn by the load, the decoupling capacitor has to be charged before the next switching cycle. For an on-chip decoupling capacitor to be effective, both effective radii criteria should be simultaneously satisfied.

High efficiency charge pump circuit

Abstract: An integrated circuit includes a charge pump to provide current at a potential which is greater than a supply potential. An oscillator provides an output to a pair of capacitors. Each capacitor is bypassed respectively by one of a pair of clamp circuits. An output transistor is gated by one of the clamp circuits to maintain a continuous output at an elevated potential, while reducing power loss caused by impedances within the charge pump circuit. By using the charge pump as a source of elevated potential, the circuit layout of the DRAM array is simplified and the potential boosting circuitry can be locataed outside of the array, on the periphery of the integrated circuit. When used with an integrated circuit device, such as a DRAM, the current from the charge pump may be supplied to nodes on isolation devices and nodes on word lines, thereby improving the performance of the DRAM without substantially changing the circuit configuration of the DRAM array.

Generalized Distribution of Relaxation Times Analysis for the Characterization of Impedance Spectra

Abstract: Impedance spectroscopy is a universal nondestructive tool for the analysis of the polarization behavior of electrochemical systems in frequency domain. As an extension and enhancement of the standard impedance spectroscopy, the distribution of relaxation times (DRT) analysis was established, where the spectra are transferred from frequency into time domain. The DRT helps to analyze complex impedance spectra by identifying the number of polarization processes involved without prior assumptions and by separating and quantifying their single polarization contributions. The DRT analysis, as introduced in literature, claims to be a model-free approach for the characterization of resistive-capacitive systems. However, a data preprocessing step based on impedance models is often required to exclude non-resistive-capacitive components off the measured impedance spectra. The generalized distribution of relaxation times (GDRT) analysis presented in this work is dedicated to complex superposed impedance spectra that include ohmic, inductive, capacitive, resistive-capacitive, and resistive-inductive effects. The simplified work flow without preprocessing steps leads to a reliable and reproducible DRT analysis that fulfills the assumption of being model-free. The GDRT is applicable for the analysis of electrochemical, electrical, and even for non-electrical systems. Results are shown for a lithium-ion battery, a vanadium redox flow battery, and for a double-layer capacitor.