BJT DC ANALYSIS

• Bjt


  One of the two basic types of transistor
• Bjt


  • Use into broad areas as a linear amplifier to boost or amplify an electrical signal
• Transistor


  First name is vacuum tube
• Vacuum tube


  Introduced by j.a fleming
• Vacuum tube


  Lee de forest added third element called the control grid, resulting in the first amplifier the triode
• Transistor construction


  • Substrate - another substances grow
  • Oxide - serves as insulator
  • Metalized contact - serves as conductor
• Main parts of a transistor

  • Collector - largest region, lightly dope
  • Base - smallest region, lightly doped
  • Emitter - heavily doped
• Doping ratio


  1. 1:10 or less
• Bipolar

  • Because we used to polarize carriers or material
  • We could inject electrons on one terminal and can also inject holes on the other terminal at the same time
  • One carrier is unipolar device
• Transistor


  • Made up of two words "transfer" and "resistor"
  • Also called transfer of resistance
• 1. Q- point

  Was set to only active region
• Alpha


  Less than one
• Beta


  r than one
• Rc coupled amplifier


  • Most common multiple bjt network
  • Use primarily in boosting voltage gain
• Darlington amplifier


  • Feeds the output of one stage directly into the input of the succeeding stage
  • Use primarily in boosting current gain
• Cascode configuration


  • Tying the collector of one transport the emitter of the other will result to network with high gain
• Feedback pair


  • Employees both np and npnp transistor
  • With high gain and increase stability
• Active region


  • Region normally employed for linear amplifiers
  • Base emitter junction is forward bias
  • Collector base junction is reverse bias
• Cut off region


  • Define as the region where collector current is zero ampere
  • Base emitter and collector base junction are both reversed bias
• Saturation region


  • Define as that region of the characteristics characteristic to the left of vcb is equal to zero
  • Base emitter and collector junctions are forward bias
• Breakdown region


  • Point where the curve take a dramatic upswing
  • Due to avalanche effect
• Operating point


  Also called quiescent point, means quiet, still, inactive
• A transistor is said to be cut off when its collector current is zero
• In active region the collector circuit acts like a current source
• When a transistor is operating in its active region is ic controlled by IB