emitter resistance การใช้

• E usually is small because the emitter resistance " r"
• The active transistor is loaded with the relatively high emitter resistance " R"
• :Meanwhile, the purpose of the bypass capacitor around any external emitter resistance is to make that impedance low for DC signals.
• :If the external emitter resistance is small or zero, then you really can't use a constant base voltage as a bias as it makes things way too sensitive to variations in R E and ?.
• In the second case ( e . g . primary and / or emitter resistance dominant ) the ( decreasing ) slope of the current decreases to a point such that the induced voltage into the secondary is no longer adequate to keep the switch closed.
• I E is then determined by the sum of the external and internal emitter resistances and I C will be I E-I B ( which, for most " large-ish " values of ? ( Beta ) can be assumed to be the same as I E ).
• Remember, the gain of a common emitter amplifier is ( roughly ) the ratio of the collector resistance over the total emitter resistance ( counting the internal R E of the transistor plus any external resistance / impedance that you add ); the bypass capacitor brings the total emitter resistance down to the typical few ohms or tens of ohms R E inherent in the transistor itself.
• Remember, the gain of a common emitter amplifier is ( roughly ) the ratio of the collector resistance over the total emitter resistance ( counting the internal R E of the transistor plus any external resistance / impedance that you add ); the bypass capacitor brings the total emitter resistance down to the typical few ohms or tens of ohms R E inherent in the transistor itself.