View source for Key Facts from Reading Chapter 1

The following facts are not profound and are possibly very obvious.  Nonetheless, they might help cement certain concepts. Please add things  you think would be helpful.
==Transistors==
[[Image:mosfet.jpg|thumb|right|400px|MOSFET diagram <ref>  [http://www.msm.cam.ac.uk/doitpoms/tlplib/semiconductors/images/mosfet.jpg  University of Cambridge] </ref>]]
*Conduction in n-type material is  from free electrons.
*Conduction in p-type material is  from holes (positive particles).
*The function of metal-oxide-semiconductor  field-effect  transistors (MOSFETs) depends on the voltage applied to the gate.
**Certain  ranges of voltage allow no current to flow between the drain and the  source. In this way, the MOSFET acts like an open switch.
**Another  particular range of voltage allows current to easily flow from the  source to the drain.
**When the voltage is in between the ranges  of open and closed switch, the MOSFET can smoothly control the amount of  current flowing.
*Bipolar Junction Transistors (BJTs) can act  as either switches or current controls as well.
==Amplifiers==
*An inverting amplifier has a negative  voltage gain, <math>\ {A_{v}}</math>.
*A noninverting  amplifier has a positive voltage gain, <math>\  {A_{v}}</math>.  (If you get this, you deserve a cookie)
*The power gain,<math>\  G</math>, is the ration of the output power to the input  power
**<math>G=\frac{P_{o}}{P_{i}}=\frac{V_o{I_o}}{V_i{I_i}}=A_v{A_{i}}=(A_v)^2\frac{R_{i}}{R_{L}}</math>
***<math>\ R_i</math> is the  amplifier's input resistance and <math>\  R_o</math> is the amplifier's output resistance.

==Decibel  Conversion==
*Power gain, <math>\ G</math>, can be converted  to decibels: 

<math>G=(A_v)^2\frac{R_{i}}{R_{L}}</math>

<math>\ G_{db}=10 log{A_{v}}^2+10 log R_i - 10 log  R_L</math>

<math>\ G_{db}=10  log |A_v|+10 log R_i - 10 log R_L</math>
*By the equation  above, we can say voltage gain in decibels can be found with this  equation: <math>\ A_{v  dB}=20 log  |A_v|</math>, where <math>\  A_v</math> is the voltage gain and <math>\  A_{v  dB}</math> is the voltage gain is decibels.
*Similarly, we  can say current gain in decibels can be found with  this equation: <math>\ A_{i  dB}=20 log  |A_i|</math>,  where <math>\  A_i</math> is  the current gain and <math>\  A_{i   dB}</math> is the current gain is decibels.

==Differential  Amplifiers==
*Differential  Amplifiers have two inputs. The terminal marked with a "+" is the  noninverting input, and the terminal marked with a "-" is the  inverting input.
*The differential input signal is given by <math>\  v_{id}=v_{i1}-v_{i2}   </math>
*The output of an ideal differential  amplifier is given by <math>\ v_o=A_d  v_{id} </math>.
*The common-mode input signal is given by the  following: <math>v_{icm}=\frac{1}{2}(v_{i1}+v_{i2})</math>.
*A real  differential amplifier's output is given by <math>\   v_o=A_d v_{id}+A_{cm} v_{icm} </math>, where <math>\ A_{cm}</math> is the common-mode signal  gain.

==References==
<references/>

==Contributors==
[[Lau, Chris | Christopher  Garrison Lau I]]