8.6 Form factor

  Semi-conductor Devices and Electronics

    1.0 Introduction
    2.0 Types of semiconductor
    3.0 Mass action law
    4.0 Electrical conductivity in semiconductor
    5.0 $p-n$ junction
    6.0 Breakdown voltage
    7.0 $I-V$ characteristics of a $p-n$ junction
    8.0 Rectifier
    9.0 Light emitting diode (LED)
    10.0 Zener diode
    11.0 Transistor
    12.0 Boolean identities
    13.0 Logic gates
    14.0 De Morgan's theorem

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8.6 Form factorThe form factor of an alternating current waveform is the ratio of the RMS value to the average value.

Mathematically, $$F = \frac{{{I_{rms}}}}{{{I_{DC}}}}$$

• For half wave rectifier, $$\begin{equation} \begin{aligned}
  {I_{rms}} = \frac{{{I_m}}}{2},\;{I_{DC}} = \frac{{{I_m}}}{\pi } \\
  F = \frac{{{I_{rms}}}}{{{I_{DC}}}} = \frac{{\frac{{{I_m}}}{2}}}{{\frac{{{I_m}}}{\pi }}} \\
  F = \frac{\pi }{2} \\
  F = 1.57 \\\end{aligned} \end{equation} $$

• For full wave rectifier, $$\begin{equation} \begin{aligned}
  {I_{rms}} = \frac{{{I_m}}}{{\sqrt 2 }},\;{I_{DC}} = \frac{{2{I_m}}}{\pi } \\
  F = \frac{{{I_{rms}}}}{{{I_{DC}}}} = \frac{{\frac{{{I_m}}}{{\sqrt 2 }}}}{{\frac{{2{I_m}}}{\pi }}} \\
  F = \frac{\pi }{{2\sqrt 2 }} \\
  F = 1.11 \\\end{aligned} \end{equation} $$