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~ Transistor rbb Calculated from data sheet figures ~

Boltzmann Constant — k 1.3806x10-23 J/K   [ Joules/Kelvin ]
Charge on a single Electron — q 1.6022x10-19 C   [ Coulomb or Amperes/sec ]
Noise Voltage referred to input — en nV/√Hz   from data sheet
Collector current for en — IC mA   from data sheet
Transistor d.c. current gain — β hFE   from data sheet @ IC
Device Temperature — T C  = ˚K
Measurement Noise Bandwidth — Bn Hz — Is not the –3dB BW as calculated Here
Calculated results using the values entered above
Emitter Internal Resistance — re Ω = VT/IC     VT = kT/q =  mV
Noise due to IC — VNIC nVrms = √2 q IBn   
Calculated Base Resistance — rbb Ω         The –ve answer   
Nota-Bene The calculated rbb result must be positive [Green] and the –ve answer negative for result to be correct ~ If the noise referred to the input is not measured in /√Hz   but in a given bandwidth then Bn should be changed to match it but enunits must still br nV~ If an output is NaN [Not a Number] check inputs are all numbers and en is not too low or Bntoo high

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