[Industry] Semiconductor-1: An Introduction to Memory and System Semiconductors

 

  1. Memory Semiconductor


Memory Semiconductor | Samsung Semiconductor Global

RAM: Random Access Memory, A form of memory that can be read and modified in any order.

 

Volatile Memory: Stored information lost if power is removed.


DRAM: Dynamic Random Access Memory, 1 transistor 1 capacitor. Necessary to ‘refresh’ data



<DRAM Cell>Introduction to DRAM (Dynamic Random-Access Memory) - Technical Articles

Capacitor: Charged) 1, Uncharged) 0  


Wordline: Provide voltage in a row to enable transistors.


Bitline: Electrons pass through Bitline to modify the data. Access a capacitor to read data.


Transistor: A switch that controls the flow of electrons. WL:1 => TR ON, WL:0 =>TR OFF



Operation:


Standby) WL: 0 => TR: Off


Write) WL:1 => TR: ON + BL: 1 => Capacitor charged => ‘1’ stored / +BL:0 => Discharge => ‘0’ Stored


Read) WL:1 => TR:ON / BL: ½ => Sense Amplifier checks the difference in voltage to determine the data.
=> The Amplifier ‘restores’ the data as the data stored in a capacitor was ‘gone’ by transmissions.




Typical 6T SRAM Cell: 4 transistors that consist two inverters + 2 transistors for WL



=> Expensive in terms of area and cost. 

=> No need to ‘refresh’ data unless the power is provided. => Faster

=> Used for Cache Memory


Two Inverters=> Flip-Flop => Maintain the status permanently by circuit loop itself.


Read-Write? => WL:1 to enable M5, M6 => Interaction with BL will read/change the data\


Flash Memory:



Floating Gate: Isolated by insulating layers => Electrons placed on it ‘trapped’ unless a high voltage is applied to induce 

Fowler–Nordheim tunneling. (Write / Erase)



Read: Control gate voltage ↑ 

FG empty => Substrate’s electrons gather to create N channel => Electric Current flows

FG has electrons => Substrate’s electrons are hindered => No Electric Current flows 




  1. System Semiconductor


A semiconductor that controls logic, calculations, and other functions


System semiconductors can be sorted into micro-components, analog IC, logic IC, optical semiconductor, etc.


– Micro-components: A system semiconductor that acts as the brain in an electronic device. There are MPU, CPU, GPU etc.


– Analog IC: A semiconductor that translates analog signals like music into digital signals for a computer to read.


– Logic IC: A semiconductor composed of logic circuits (AND, OR, NOT, etc.) that controls a specific part of a product.


– Optical semiconductor: A semiconductor that translates light into electrical signals and vice versa.


(System Semiconductor | Samsung Semiconductor Global)



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