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why common emitter configuration is used more than common base configuration of transistor for amplification purpose? when common base configuration provides more stability than of common emitter configuration

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Common collector: Current gain but no voltage gain

Common base: Voltage gain but no current gain

Common emitter: Some voltage and some current gain, depending on the impedances in the emitter and collector circuits.

I've never used the common base configuration, I understand it is used mostly for the input stages of high frequency amplifiers.

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Compared to other configurations, common emitter (CE) amplifiers tend to have higher input impedance and lower output impedance, and better-than-unity gain, which makes them very useful for both input buffering and voltage gain applications.

By contrast, common base (CB) amplifiers have low input impedance and higher output impedance. CB amps aren't so much for voltage gain as they are for power gain; with a CB configuration, any power sourced by the input is passed through to the load, in addition to the power added by the transistor itself, but this shows up as current gain.

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  • \$\begingroup\$ {thanks} is there any current gain in transister? \$\endgroup\$ – coldshine Apr 26 '11 at 20:37
  • \$\begingroup\$ bipolar junction transistors (BJTs) are inherently current-gain devices. the collector resistor in the CE configuration translates the increased current to a voltage. \$\endgroup\$ – JustJeff Apr 26 '11 at 23:19
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    \$\begingroup\$ Common-base amplifiers are ENTIRELY about voltage gain, because the current gain is actually slightly less than unity -- some of the emitter current flows through the base. \$\endgroup\$ – Dave Tweed Jan 13 '18 at 18:26
  • \$\begingroup\$ Both - common emitter and common base - have the same output resistance, which - praactically - is identical to the collector resistor Rc. \$\endgroup\$ – LvW Apr 26 '18 at 15:59

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