A 36μa 4MB PSRAM with quadruple array operation

I, In t roduc t i on Recently, P S ~ U ~ O s t a t i c RAH CllC21 (PSRAH) c l i i ~ ~ have been used w i d e l y i n m a i l wstems such as personal computers and p r i n t e r bu f fe rs . Since PSRAH uses a dynamic type of memory cell which cons is t s of one HOS t r ans i s to r and one CaPacitor. i t needs a per iod i c re f resh cyc le to re1,ain data. Because i t i s ex t rese ly d e s i r a b l e f o r PSRAn t o act as i f i t i s S R A I I , t h i s p e r i o d i c re f resh cyc le has to be c a r r i e d aut au tomat i ca l l y by the PSRA'I i t s e l f . Th is re f resh mode is c a l l e d s e l f r e f r e s h mode. In s e l f node. a IOW power d i s s i p a t i o n i s essential because t he c h i p v i l i r e q u i r e bat tery 'backup i n standby node. However. the sore nenory d e n s i t y increases, to I H b i t s , f o r i ns tance . t he h isher the power d i r s i P a t i o n becomes.