COMMON DRAIN Meaning and
Definition
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Common drain, also known as source follower or grounded source amplifier, is a type of transistor configuration commonly used in electronic circuits, especially in analog applications. It is one of the three basic transistor amplifier configurations, alongside common emitter and common base.
In a common drain configuration, the drain terminal of the transistor is connected to a common point, usually ground. The input signal is applied to the gate terminal, while the output is taken from the source terminal. This configuration is characterized by high input impedance and low output impedance, thus allowing it to serve as a voltage buffer or impedance matching circuit.
The common drain configuration is often employed in applications that require low voltage gain but high current gain. It offers a high degree of stability, as it has negative feedback that reduces distortion and improves linearity. Furthermore, it is suitable for driving low impedance loads as it can provide a relatively high current output.
One of the key advantages of the common drain configuration is its ability to preserve the voltage level of the input signal, making it suitable for impedance matching between two devices with different output and input impedance levels. It also provides a low output impedance, enabling it to drive subsequent stages or loads efficiently.
Overall, the common drain configuration offers a balanced combination of input and output impedance that makes it a useful building block in various electronic circuit designs.
Etymology of COMMON DRAIN
The term "common drain" consists of two words, each with its own etymology:
1. Common: The word "common" has its roots in the Latin word "communis", which means "belonging to all" or "shared". It entered English through Old French and Middle English, retaining its general meaning of "belonging to or shared by all members of a group or community".
2. Drain: The word "drain" originated from the Old English word "drēahnian", which meant "to strain off liquid" or "draw off water". It shares its origins with the Old Norse word "dreyna" and the Middle Low German word "drēnen". The word eventually evolved to its current meaning of a pipe that carries off waste liquids or water.
