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High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

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Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of
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PHOTOELECTRIC EFFECT

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PHOTOELECTRIC EFFECT
In order to escape from a metal being bombarded by
light, an electron requires an amount of energy qF
and emits an energy hn. The work function F, is the
minimum amount of energy needed to cause an
electron to leave the metal. It is a constant for each
metal. Tungsten: 4.5 eV.
           E = hv - qF  (must know)
Em = maximum energy of emitted electrons [J]
h = Planck's constant, 6.63×10-34 J-s
v= (nu) frequency [Hz]
q = electron charge 1.6022 × 10-19 [c]
qf = (phee) the work function of the metal [eV]