DESIGN THEORY OF JUNCTION TRANSISTORS 1301 



puted from the gradients of the minority carrier densities at the barriers. 

 In the ac analysis, the forward rotating time function e'^ is used. In 

 general, the first-order solution for small signals is obtained by assum- 

 ing that the disturbance associated with e**^' is small, by neglecting its 

 powers and harmonics, and by using first-order expansions, e.g., 





The ac magnitudes such as it^i , pei , Ud , represent complex phasors of 

 the form ae^*. A list of S3rmbols is given in Section 1.5. 



1 .3 ANALYSIS 



In the base layer at a^ = 0, 



P = PeO + Peie = Pne KW 



at x = w^o , 



p = Pco-hPcie = Pne " (Id; 



in which Ve = Veo + Veic"* 



and Vei « Veo and Vd « Vco so that 



PeO ^ Pne'^^'^'^^'pcl ^ PeO ^ Vd 



kT 



Pel ^ Pco -TTf^ ^cl 



Pne'^'-'^'Pcl ^ Pco ^ 



PeO , Pco , ^eo , and Veo 2iVQ avcragc values while pei , Pci , Ve\ , and Vd 

 are ac phasors. 



The continuity equation for holes for one-dimensional flow is: 



d'p _ ( pn- p \ dp (2) 



in which r is hole lifetime. A solution to equation (8-18) is: 



p ^ p^ + Ae^'^ + Be-'^' + C."'^^"' + De'-"^^'^' (3) 



where L = VD^ and s = (1 + ioiTY'^. 



Application of the boundary values of equation (la) and (lb) to 



