Definition
A transistor amplifier circuit configuration in which the base terminal is connected to ground (the common reference point), the input signal is applied to the emitter, and the output signal is taken from the collector. This arrangement provides voltage gain with no current gain and presents a low input impedance with a high output impedance. It is commonly used at high frequencies because it has good isolation between input and output.
Plain English
A way of wiring a transistor so that one of its three legs (the base) is held at the circuit's reference point. The signal goes in one of the other legs and comes out larger on the third leg. This wiring style works especially well for high-frequency signals like radio.
Context Anchor
Seen in aircraft electronics, radio, and avionics maintenance descriptions rather than normal cockpit procedures.
Derivation
Named for the way the transistor is wired: the base terminal is grounded, meaning it is connected directly to the circuit's common reference point. The three classic transistor amplifier configurations are named for whichever terminal is grounded -- grounded-base, grounded-emitter, and grounded-collector.
Why Pilots Care
Pilots do not design these circuits, but understanding the term helps when reading avionics manuals, troubleshooting guides, or discussions of how aircraft radios and navigation equipment work internally.
Intuition Check
Do not read grounded here as “the airplane is not allowed to fly.” In this term, grounded means the transistor’s base is tied to the circuit’s reference point.
Example Sentence 1
The radio's high-frequency stage uses a grounded-base amplifier to boost the incoming signal without feedback problems.
Example Sentence 2
A technician replaced the faulty grounded-base amplifier to restore clear transmission on the aircraft radio.