Väikesignaal

Väikesignaal refers to a signal with a small amplitude relative to the operating point of a system. In electronics, it is often used to describe the behavior of a circuit or device when subjected to small, time-varying inputs. This concept is particularly important in the analysis of amplifiers, transistors, and other semiconductor devices. When a device is biased at a certain operating point, a small signal superimposed on this bias will cause relatively small deviations in the device's current and voltage. Analyzing these small signal deviations allows engineers to understand the AC characteristics of the device, such as its gain, input impedance, and output impedance, without needing to consider the complex, non-linear DC behavior.

The analysis of small signals typically involves linearizing the device's behavior around its DC operating point. This is often achieved using techniques like small-signal models, such as the hybrid-pi model for bipolar junction transistors or the common-source model for MOSFETs. These models represent the device as a network of linear components (resistors, capacitors, dependent sources) that accurately predict the response to small AC signals. The term "väikesignaal" emphasizes that the signal's amplitude is small enough that the linear approximation remains valid and does not cause significant distortion or clipping. This approach simplifies circuit analysis and design, enabling the calculation of key performance parameters.