Why SRAM and DRAM do not use flip-flop?

Discussion in 'Homework Help' started by feli, Jul 8, 2011.

  1. feli

    Thread Starter New Member

    Apr 24, 2011
    6
    0
    Hi everybody,

    Could you please help me with the following things,

    A 4-bit register uses 4 flip-flops. (each flip-flop stores a bit).
    SRAM uses 6 transistors to store a bit, whereas DRAM uses 1 transistor and 1 capacitor to store a bit. My question is why SRAM and DRAM do not use flip-flop to store a bit?

    (I am sorry for my English, and I am not a native speaker, and also I am a newbie)

    Regards
    Feli
     
  2. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    A flip flop needs much more components to be made. It needs approximately 14 flip flops, so it's a matter of economy.
    I 'll try to be more specific on the number and find a schematic too.
     
  3. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    2,689
    2,750
    Actually, an SRAM does use flip-flops constructed of 4 transistors. The other two are used for reading/writing data. If it didn't use flip-flops...it wouldn't be static.
     
  4. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    You could call it a flip flop, but the construction of a standard flip flop is much different than a 6t SRAM.
     
  5. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    2,689
    2,750
    Ahhh...but there are many ways a flip-flop can be constructed...relays, DTL, vacuum tubes, transistors...just because the circuit doesn't look like a typical flip-flop, doesn't mean it isn't one. To be technically precise, these should all be called "bistable multi-vibrators". The term "flip-flop", according to wikipedia, wasn't even well defined, historically:

    I submit for the jury that a SRAM cell is, indeed, a flip-flop.
     
  6. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    2,689
    2,750
    BTW, I can (and I have) build a practical SR flip-flop with two cmos inverters and two resistors.
     
  7. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    Well, ok. It is a flip flop since it can have only two states. What I wanted to point is that it's not your classic 7474 flip flop.
     
Loading...