BJT Common Emitter Amplifier

  • BIAS
  • BJT
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In this circuit the base is the driven element. The input signal is injected into the base-emitter circuit whereas the output signal is taken out from the collector-emitter circuit. The EB junction is forward biased and CB junction is reverse biased. This is how it works: VBE is increased as the input rises. This increases the forward bias of the BE junction causing an increase in IB. As IC is proportional to IB, IC increases and the resistance across the collector resistor increases in the CE loop. This results in the drop in VCE. Hence the negative half-cycle of the output is obtained. It means that a positive-going input signal becomes a negative-going signal – the input is inverted at the output. The CE amplifier has a moderately low input resistance and a moderately large output resistance. Its current gain is high (50-300).

Circuit info


Created on: 25 Feb 2013
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