Search results
Results from the WOW.Com Content Network
In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit. [1]Quantitatively, the impedance of a two-terminal circuit element is the ratio of the complex representation of the sinusoidal voltage between its terminals, to the complex representation of the current flowing through it. [2]
A single impedance has two terminals to connect to the outside world, hence can be described as a 2-terminal, or a one-port, network.Despite the simple description, there is no limit to the number of meshes, [note 6] and hence complexity and number of elements, that the impedance network may have.
The negative impedance converter (NIC) is an active circuit which injects energy into circuits in contrast to an ordinary load that consumes energy from them.This is achieved by adding or subtracting excessive varying voltage in series to the voltage drop across an equivalent positive impedance.
The op-amp inverting amplifier is a typical circuit, with parallel negative feedback, based on the Miller theorem, where the op-amp differential input impedance is apparently decreased to zero Zeroed impedance uses an inverting (usually op-amp) amplifier with enormously high gain A v → ∞ {\displaystyle A_{v}\to \infty } .
For example, in order to match an inductive load into a real impedance, a capacitor needs to be used. If the load impedance becomes capacitive, the matching element must be replaced by an inductor. In many cases, there is a need to use the same circuit to match a broad range of load impedance and thus simplify the circuit design.
It is the time required to charge the capacitor, through the resistor, from an initial charge voltage of zero to approximately 63.2% of the value of an applied DC voltage, or to discharge the capacitor through the same resistor to approximately 36.8% of its initial charge voltage.
In electronics, a constant phase element is an equivalent electrical circuit component that models the behaviour of a double layer, that is, an imperfect capacitor (see double-layer capacitance). Constant phase elements are also used in equivalent circuit modeling and data fitting of electrochemical impedance spectroscopy data.
Figure 2: Amplifier with feedback capacitor C C. Figure 2A shows an example of Figure 1 where the impedance coupling the input to the output is the coupling capacitor . Thévenin voltage source drives the circuit with Thévenin resistance .