DESIGN THEORY OF JUNCTION TRANSISTORS 1309 



y-- kT ^-° sinh (s,w,/L,) \} + ^J (^^) 



_ dw Sp 



""" " dV. L, sinh is,Wo/L,) ^^ ^^^^ 



'^^^ " [w; L,UnhX,wo/L,) ^^' + ^^^d L^ ^ SJ 



(38) 



The change in signs which occurs in going from equations (31) and 

 (32) to equations (37) and (38) takes place because the current re- 

 placed by I PC had the opposite assigned positive sense. 



1.5 SYMBOLS USED IN THE APPENDIX 



Cc , Ctc = collector barrier capacitance. 



Cn = emitter barrier capacitance. 



Dn , Dp = diffusion constants for electrons and holes 



^0 = (Pp + np)/(pp/Dn + Up/Dp) 



Ea = ip = electric field associated with current at thermal equilibrium 

 carrier densities. 



El , Eo = ac and dc components of Ea 



he , Ineo , I nei , he , hco , hci = total, average, and ac emitter and col- 

 lector electron currents 



Ipe , Ipeo , I pel , I pc , I pcQ , I pel = total, average, and ac emitter and col- 

 lector hole currents 



kT/q = thermal energy of carriers = 0.026 electron-volt 



Lp , Ln = diffusion lengths for holes and electrons 



m2 = 



A/ I ^ ," I 4- ^^^- decay constant for average elec- 

 y \2DoMoJ ^ Dot ^ ^ 



2DoMo 



tron density in the collector 

 Mo = (Pp — hnp)/{pp = Up) 



rip , Tin = thermal equilibrium electron densities in p and n regions 

 Ueo , riei = dc and ac components of electron density at emitter junction 

 Pn, Pp = thermal equilibrium hole densities in n and p regions 

 Peo , Pel , Pco , Pel = dc aud ac components of hole density at emitter 



and collector junctions 

 q = electronic charge, 1.6 X 10"^^ coulombs 

 Ve = ac emitter resistance 



I(-+£|.)V[U-+rI.)]'+S 



* The factor a* = (1 + a- cApc) is current dependent. At small average collector 

 currents, it is (1 + <rnc/2<rpc) and rises to (1 -f ancApc) at high current densities. 



