Definition
A transistor amplifier circuit configuration in which the emitter terminal is connected directly to the common ground (or circuit reference) line, the input signal is applied to the base, and the amplified output is taken from the collector. This arrangement produces both voltage gain and current gain, and inverts the phase of the signal by 180 degrees between input and output.
Plain English
A small electronic circuit built around a transistor where one of the transistor's three legs (the emitter) is tied to the common reference line of the circuit. The signal goes in one leg and comes out the third leg, much stronger than it went in.
Context Anchor
Seen in aircraft electronics, avionics, radio, audio, and instrument-system circuit discussions.
Derivation
Grounded' means tied to the circuit's common reference (the 'ground' line). 'Emitter' is the transistor terminal that emits charge carriers into the device. 'Amplifier' comes from Latin amplificare, meaning 'to enlarge.' Together: an enlarging circuit in which the emitter leg is the one tied to ground.
Why Pilots Care
Reliable signal amplification in communication and navigation radios depends on correct operation of this common circuit configuration.
Grounding Statement
In this circuit, the emitter acts like the fixed reference point while the transistor uses a small input signal to control a larger output signal.
Intuition Check
“Grounded” does not mean the circuit is connected to the earth. In an aircraft, it usually means connected to the circuit’s reference or return point, which may be the aircraft structure or an internal common point.
Example Sentence 1
The receiver's first stage uses a grounded-emitter amplifier to boost the weak antenna signal before it reaches the rest of the circuit.
Example Sentence 2
During preflight checks the avionics shop verified that the grounded-emitter amplifier provided proper gain to the audio input.