x
Home / 🔮 world building / science and engineering / Engineering / electronics engineering / Abstractions of Electronics Engineering

Abstractions of Electronics Engineering

  • Internals of a resistor
  • How a NAND Flash is engineered practically -

Q:
NAND FLASH is slower than flip flops

NAND FLASH and flip-flops are made of NAND Gates
Both NAND Flash and flip flops operate at 5V

The difference is that NAND FLASH uses floating gate transistors to store charge
NAND Gates are made of transistors

Flash drive is made up of NAND FLASH and Cache memory
Cache memory is made of flip-flops and has speeds equivalent to a CPU

In other words, what makes Cache memory faster than Flash drives?

A:
NAND Gates are logical circuits
Gate contact of a MOS transistor is different from it.

NAND gates don't make the internal circuits of a flip-flop in practice.
Flip-flops are simplified to save space.
Ex: SRAM cell made from CMOS pass transistor logic

NAND Flash memory is more akin to DRAM than SRAM.
So it is slower than SRAM for the same reasons that DRAM is slower than SRAM.
That is, detecting and amplifying signal from a floating gate, and performing error correction.

The reason why flash memory is slower is because it has a large amount of charge to be put through an isolator (SiO2, so the drift velocity is much slower) onto the floating gate. This makes time.

Transistors which have a normal gate contact can have that one fully charged and de-charged within picoseconds.

A2:
An answer that assumes NAND Flash is made of gates probably:

A flip-flop is just two or four gates.
A NAND Flash is read a row at a time, and written to serially.
The data needs to be latched somewhere for transfer via a parallel bus.
The address decoding takes time.
Considering a flash drive than a flash chip, there are also MCU processing in the data path.

Left-click: follow link, Right-click: select node, Scroll: zoom
x