(內(nèi)存基本知識)-dram工作原理(編輯修改稿)
2025-08-21 13:26 本頁面
【文章內(nèi)容簡介】 R D L I N E 2W OR D L I N E 3DAT A BI TRamaxel Technology Limited Ramaxel Technology Limited Confidential Activating a Row ? Activating a Row – Must be done before a read or write – Just latch the row address and turn on a single wordline BITLINE 0BITLINE 0BITLINE 1BITLINE 1BITLINE 2BITLINE 2BITLINE 3BITLINE 3ROW DECODERSELECTS A SINGLE WORDLINECOLU MN MUL T IPLEX ER CONNECT S A S INGL E B IT L INECOLU MNADD RESSROWADDRPREC HAR GE CONT ROL L INEW OR D L I N E 0W OR D L I N E 1W OR D L I N E 2W OR D L I N E 3DAT A BI TRamaxel Technology Limited Ramaxel Technology Limited Confidential Writing ? Writing – A row must be active – Select the column address – Drive the data through the column mux – Stores the charge on a single capacitor BITLINE 0BITLINE 0BITLINE 1BITLINE 1BITLINE 2BITLINE 2BITLINE 3BITLINE 3ROW DECODERSELECTS A SINGLE WORDLINECOLU MN MUL T IPLEX ER CONNECT S A S INGL E B IT L INECOLU MNADD RESSROWADDRPREC HAR GE CONT ROL L INEW OR D L I N E 0W OR D L I N E 1W OR D L I N E 2W OR D L I N E 3DAT A BI TZEROONERamaxel Technology Limited Ramaxel Technology Limited Confidential Reading ? Reading – A row must be active – Select the column address – The value in the senseamplifier is driven back out BITLINE 0BITLINE 0BITLINE 1BITLINE 1BITLINE 2BITLINE 2BITLINE 3BITLINE 3ROW DECODERSELECTS A SINGLE WORDLINECOLU MN MUL T IPLEX ER CONNECT S A S INGL E B IT L INECOLU MNADD RESSROWADDRPREC HAR GE CONT ROL L INEW OR D L I N E 0W OR D L I N E 1W OR D L I N E 2W OR D L I N E 3DAT A BI TZEROONERamaxel Technology Limited Ramaxel Technology Limited Confidential The SenseAmplifier ? SenseAmplifier – A pair of crosscoupled inverters ? Basically an SRAM element – Weaker than the column mux ? Write data will ―outmuscle‖ the senseamplifier – Keeps the data at full level BITLINEBITLINE W OR D LI N EPR EC H AR GE C ON T R OL LI N ERamaxel Technology Limited Ramaxel Technology Limited Confidential Precharge ? Precharge – Inactive state (no wordlines active) – Precharge control line high ? Ties the two sides of the senseamp together – This makes the bitlines stay at VDD/2 ? Only stable as long as the precharge control line is high—otherwise this is unstable! – No capacitors connected BITLINEBITLINE W OR D LI N EPR EC H AR GE C ON T R OL LI N ERamaxel Technology Limited Ramaxel Technology Limited Confidential Activation Revisited ? Activation – Turn off the precharge control line ? Makes the senseamp unstable—it wants to go to either 0 or 1 instead of staying at VDD/2 – A very very very short time later, turn on the wordline of the row to be activated. ? Couples the capacitor onto the bitlines – This ―tips‖ the bitlines to hold the stored value. – The senseamp amplifies the capacitor back to full value. (hence the name!) BITLINEBITLINE W OR D LI N EPR EC H AR GE C ON T R OL LI N ERamaxel Technology Limited Ramaxel Technology Limited Confidential DRAM Refresh ? Because the stored memory value is stored on a
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