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A large signal is any signal having enough magnitude to reveal a circuit's nonlinear behavior. The signal may be a DC signal or an AC signal or indeed, any signal. How large a signal needs to be (in magnitude) before it is considered a large signal depends on the circuit and context in which the signal is being used. In some highly nonlinear ...
Fig. 3: Small-signal model for impedance calculation. A circuit is a current source only to the extent that its output current is independent of its output voltage. In the circuits of Fig. 1 and Fig. 2, the output voltage of importance is the potential from the collector of Q 3 to ground.
Full hybrid-pi model. The full model introduces the virtual terminal, B′, so that the base spreading resistance, r bb, (the bulk resistance between the base contact and the active region of the base under the emitter) and r b′e (representing the base current required to make up for recombination of minority carriers in the base region) can be represented separately.
Large-signal modeling is a common analysis method used in electronic engineering to describe nonlinear devices in terms of the underlying nonlinear equations. In circuits containing nonlinear elements such as transistors, diodes, and vacuum tubes, under "large signal conditions", AC signals have high enough magnitude that nonlinear effects must be considered.
Figure 4: Small-signal circuit for N-channel MOSFET common-source amplifier. Figure 5: Small-signal circuit for N-channel MOSFET common-source amplifier using Miller's theorem to introduce Miller capacitance C M. Bandwidth of common-source amplifier tends to be low, due to high capacitance resulting from the Miller effect.
Slewing is associated with the large-signal performance of an op amp. Consider, for example, an op amp configured for a gain of 10. Let the input be a 1 V, 100 kHz sawtooth wave. That is, the amplitude is 1 V and the period is 10 microseconds. Accordingly, the rate of change (i.e., the slope) of the input is 0.1 V per microsecond.
An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude (magnitude of the voltage or current) of a signal applied to its input ...
Figure 2: Small-signal model for calculating various parameters; Thévenin voltage source as signal. For the case when the common-base circuit is used as a voltage amplifier, the circuit is shown in Figure 2. The output resistance is large, at least R C || r O, the value which arises with low source impedance (R S ≪ r E).