Electronic Devices

Special Purpose p-n Junction Diodes, Junction Transistor


  • A TRANSISTOR transfers current from low resistance circuit to high resistance circuit.
  • EMITTER is heavily doped, moderate in size and supplies majority charge carries to base.
  • BASE is thinnest in size and lightly doped. It allows most of the charge carriers injected in to it to flow into collector without getting neutralized.
  • COLLECTOR is moderately doped, thickest in size and its function is to collect the majority charge carriers from base.
  • p - n - p Transistor:-

  • p-n-p transistor

  • n-p-n transistor

  • n-p-n transistor

  • In a transistor, the direction of arrow on the emitter represents the direction of flow of conventional current.
  • Input resistance in CE configuration of P-N-P transistor is \tt R_{i}=\left(\frac{\Delta\ V_{BE}}{\Delta\ I_{B}}\right)V_{CE}
  • The output resistance in CE configuration of PNP transistor is \tt R_{0}=\left(\frac{\Delta\ V_{CE}}{\Delta\ I_{C}}\right)_{I_{B}}
  •  In CE configuration transistor, the current gain is \tt \beta_{d.c}=\frac{I_{C}}{I_{B}},\beta_{a.c}=\frac{\Delta I_{C}}{\Delta I_{B}}
  • Relation between α, β : \tt \beta = \frac{\alpha}{1-\alpha};\alpha=\frac{\beta}{1+\beta}
  • \tt \frac{1}{\alpha}-\frac{1}{\beta}=1
  • The amplifier which is used to rise the voltage level is called as voltage amplifier. Voltage gain \tt A_{v}=\frac{\Delta\ V_{CE}}{\Delta\ V_{BE}}=\frac{\Delta\ I_{C}}{\Delta\ I_{B}}\times \frac{R_{L}}{R_{i}}=\beta\ \times\frac{R_{L}}{R_{i}}
  • The amplifier which is used to rise the power level is called as power amplifier.
    Power gain (AP) = β AV
    \tt =\beta\times\frac{\Delta\ V_{CE}}{\Delta\ V_{BE}}
  • Power gain (AP) = \tt =\beta^{2}\times\frac{R_{L}}{R_{i}}

View the Topic in this video From 00:05 To 05:25

Junction Transistor View the Topic in this video From 00:09 To 13:01

Disclaimer: Compete.etutor.co may from time to time provide links to third party Internet sites under their respective fair use policy and it may from time to time provide materials from such third parties on this website. These third party sites and any third party materials are provided for viewers convenience and for non-commercial educational purpose only. Compete does not operate or control in any respect any information, products or services available on these third party sites. Compete.etutor.co makes no representations whatsoever concerning the content of these sites and the fact that compete.etutor.co has provided a link to such sites is NOT an endorsement, authorization, sponsorship, or affiliation by compete.etutor.co with respect to such sites, its services, the products displayed, its owners, or its providers.