CommonSourceVerstärker

CommonSourceVerstärker, also known as a common-source amplifier, is a fundamental building block in analog electronic circuits. It is a type of field-effect transistor (FET) amplifier where the input signal is applied to the gate and the output is taken from the drain, with the source terminal common to both the input and output circuits. This configuration is widely used due to its high voltage gain and high input impedance.

The high input impedance of the common-source amplifier is a significant advantage as it minimizes the loading effect on the signal source. This means that the amplifier draws very little current from the preceding stage, preserving the integrity of the input signal. The output impedance is typically moderate, making it suitable for driving subsequent stages or loads.

A key characteristic of the common-source amplifier is its inherent phase inversion. The output signal is 180 degrees out of phase with the input signal. This is a direct consequence of the transistor's operation where an increase in gate-source voltage leads to a decrease in drain current, resulting in a lower output voltage across the drain resistor.

Common-source amplifiers can be implemented using both n-channel and p-channel FETs, such as MOSFETs and JFETs. The specific biasing circuit employed determines the operating point of the transistor and influences the amplifier's performance, including its gain, bandwidth, and distortion characteristics. Due to its versatility and desirable properties, the common-source amplifier is a cornerstone in the design of amplifiers, oscillators, and other analog circuits.