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The actual output impedance for most devices is not the same as the rated output impedance. A power amplifier may have a rated impedance of 8 ohms, but the actual output impedance will vary depending on circuit conditions. The rated output impedance is the impedance into which the amplifier can deliver its maximum amount of power without failing.
Z-parameters are also known as open-circuit impedance parameters as they are calculated under open circuit conditions. i.e., I x =0, where x=1,2 refer to input and output currents flowing through the ports (of a two-port network in this case) respectively.
A voltage divider referenced to ground is created by connecting two electrical impedances in series, as shown in Figure 1. The input voltage is applied across the series impedances Z 1 and Z 2 and the output is the voltage across Z 2. Z 1 and Z 2 may be composed of any combination of elements such as resistors, inductors and capacitors.
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 small output impedance means that the series combination of the original voltage source and the voltage follower presents a Thévenin voltage source with a lower Thévenin resistance at its output node; that is, the combination of voltage source with voltage follower makes a more ideal voltage source than the original one.
In electrical engineering, impedance matching is the practice of designing or adjusting the input impedance or output impedance of an electrical device for a desired value. Often, the desired value is selected to maximize power transfer or minimize signal reflection .
A series circuit with a voltage source (such as a battery, or in this case a cell) and three resistance units. Two-terminal components and electrical networks can be connected in series or parallel. The resulting electrical network will have two terminals, and itself can participate in a series or parallel topology.
The formula above assumes zero output impedance. When an amplifier with nonzero output impedance is used, its output impedance should be added to R e {\displaystyle R_{\rm {e}}} for calculations involving Q e s {\displaystyle Q_{\rm {es}}} .