346 



THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1954 



path supplies the complex conjugate poles and a parasitic real zero, 

 while a parallel tee in the input path provides the conjugate zeros and a 

 real pole. 



It has been found that the experimental performance of the various 

 non-inductive filters described can be predicted with precision from the 

 theory. 



Noti-induclive Phase Sections 



Non-minimum phase networks are used extensively to provide a 

 specified variation in phase with frequency without introducing any 

 change in attenuation. Such all-pass networks consisting only of reactive 

 elements are usually designed as lattices or bridged tee sections. It is 

 theoretically possible and practically desirable to represent any complex 

 all-pass structure by tandem arrangements of two basic all-pass sections 

 called first degree and second degree. The first degree structure pro- 



t-V\A^ 



I 



AAA-- 



(a) 



ONE 180° SECTION 



JCJ 



^^-i— VvaH W pvvv-r- 



(b) 



I 



•-AAA^ 



AW— I 



-VA--- 



-X— X- 



'-AW-' 



TWO 180° SECTIONS 



J^ 



-o-o- 



JW 



Fig. 13 — • Non-inductive active phase sections. 



