An o p t i m i z a t i o n of advanced s e l f -a l i g n e d t r a n s i s t o r s f o r a low-power ECL c i r c u i t has been s t u d i e d . The ECL c i r c u i t h a s been f a b r i c a t e d with t h e 0.5-pm r u l e and a 30-GHz fT technology and has been e v a l u a t e d i n terms of t h e p r o p a g a t i o n d e l a y t i m e of r i n g o s c i l l a t o r s and a 1 / 8 s t a t i c d i v i d e r . W e have obtained 39-ps/1.6-mW ECL c i r c u i t and 12.5-GHz 1 / 8 s t a t i c d i v i d e r . I n t r o d u c t i o n B i p o l a r ECL LSIs a r e t h e components i n h i g h p e r f o r m a n c e d i g i t a l s y s t e m s s u c h a s m a i n f r a m e c o m p u t e r s a n d b r o a d b a n d t r a n s m i s s i o n systems. Today, ECL performance i s sub-100 p s i n 10K-gate V L S I s ( 1 ) . However, t h e demand f o r h i g h e r s p e e d and l a r g e r i n t e g r a t i o n i s i n c r e a s i n g , while t h e power d i s s i p a t i o n has not changed much because of t h e c o o l i n g problem. I n t h i s work, we have s t u d i e d t h e o p t i m i z a t i o n Analysis of ECL c i r c u i t The p r o p a g a t i o n d e l a y t i m e of an ECL c i r c u i t can be expressed a s t h e summation of t h e v a r i o u s CR t i m e c o n s t a n t s . A t o F : Ccb : Cbe : Csub: CL : r e : RL : P r o p o r t i o n a l i t y c o n s t a n t s Collector-base junction capacitance Base-emitter junction capacitance Cje + d i f f u s i o n capacitance Cdk C o l l e c t o r -s u b s t r a t e junction capacitance P a r a s i t i c capacitance of pull-up r e s i s t o r and i n t e r c o n n e c t i o n Base r e s i s t a n c e (sum of i n t e r n a l and e x t e r n a l ) Emitter s e r i e s r e s i s t a n c e Re + d i f f e r e n t i a l r e s i s t a n c e kT/qIc Pull-up r e s i s t o r value of ECL c i r c u i t The propagation d e l a y time of a low-power ECL c i r c u i t made by t h e conventional ESPER process has been analyzed with S P I C E c i r c u i t s i m u l a t o r b a s e d on e q u a t i o n 1 t o f i n d which t i m e c o n s t a n t p l a y s t h e most s i g n i f i c a n t r o l e i n determining t h e delay time ( F i g . 1 ) . The power CH2771-4/89/0000(0169)$1 .OO @ 1989 IEEE T -1 d i s s i p a t i o n of t h e ECL g a t e was s e t t o 1 . 6 mW. I t i s found t h a t 4 1 % of t h e d e l a y time i s due t o t h e t i m e c o n s t a n t Ccb(RL+re) and 28% t o C b e r e . T o improve t h e d e l a y t i m e , i t i s e f f e c t i v e t o r e d u c e t h e s e t i m e c o n s t a n t s . Among t h e s e parameters, RL and r e a r e of f i x e d v a l u e s determined by t h e switching c u r r e n t of t h e I n forward b i a s c o n d i t i o n , Cdk r a t h e r than Cje i s a dominant f a c t o r . T h e r e f o r e , s m a l l e r dimensions and h i g h e r c u t -o f f frequency ( f T ) must be r e a l i z e d t o o b t a i n lower Ccb and Cbe.
Process designCcb has been reduced by minimizing t h e base r e g i o n with t h e 0.5-pm d e s i g n r u l e . The t r a n s i...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.