Differences between SRAM and DRAM

SRAM(Static Random Access Memory(SRAM)is the mainstream high-speed random access memory chip and one of the core storage components of electronic equipment,which is often confused with DRAM used for equipment storage.Both of them belong to RAM memory,but they are very different in storage principle,hardware structure and operating characteristics,which also creates their completely different application scenarios.
 

The core feature of SRAM is that it can protect data by power-on and does not need periodic refresh.It relies on bistable latch structure to store data.As long as the equipment is continuously powered,it can stably retain binary data of 0 and 1 without additional charge replenishment operation,which is also the core reason for its"static"naming.It should be noted that SRAM is a volatile memory,and the stored data will be completely lost after power failure,so it is impossible to retain information for a long time.
 

On the hardware structure,the mainstream SRAM adopts the classic 6T memory cell structure,which is made up of six MOS transistors.Its core is two sets of cross-coupled CMOS inverters with two read-write control transistors to form a bistable latch circuit.The inverter switches high and low levels through the turn-on and turn-off of PMOS and NMOS transistors,forming a stable circuit state,and can complete high-speed data reading and writing with word lines and bit lines,and the circuit is extremely stable.
 

Compared with SRAM,DRAM(Dynamic Random Access Memory)has a simpler structure,and the standard cell is 1 transistor+1 capacitor architecture.DRAM relies on capacitor charge to store data,but there is a natural leakage problem in the capacitor,and the charge will continue to be lost.Therefore,it is necessary to refresh and replenish power regularly to retain data,which is also the origin of"dynamic storage".Mobile phone LPDDR storage and computer memory chips all adopt DRAM architecture.
 

Anyway.Structurally,the SRAM single cell 6 transistor design occupies a larger chip area and has a higher manufacturing cost.DRAM minimalist architecture has high integration,large capacity and outstanding cost performance.In performance,SRAM does not need to be refreshed,the circuit response is fast,the reading and writing speed is much better than DRAM,and the delay is extremely low.DRAM has performance loss due to frequent refresh,and its running speed is relatively limited.Because of the difference in characteristics,SRAM is mainly used in scenes that require extreme speed,such as CPU cache,while DRAM is generally used as the main running memory of equipment.