Which of the following memories uses one transistor and one capacitor as a basic memory unit

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URSC ISRO Technical Assistant Electronics 13 November 2016 Official Paper
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  1. SRAM
  2. DRAM
  3. Both SRAM and DRAM
  4. None

Answer (Detailed Solution Below)

Option 2 : DRAM
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Detailed Solution

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In a DRAM, a capacitor is used to store a bit of data along with a MOSFET (transfer device) which acts as a switch.

The circuit is as shown:

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In a DRAM:

  • Periodic refreshing is required.
  • The information is stored in a capacitor.
  • Both read and write operations cannot be performed simultaneously.

26 June 1

For an SRAM, the storage element is a  flip-flop.

A comparison of SRAM and DRAM is as shown:

Basis of Comparison

SRAM

DRAM

Speed

Faster

Slower

Size

Small

Larger

Cost

Expensive

Cheap

Used in

Cache Memory

Main memory

Density

Less Dense

Highly dense

Construction

Complex and uses transistors and latches

Simple and uses capacitors and transistor

Single block of memory requires

6 transistors

Only one transistor

Charge Leakage

Not present

Present and hence require periodic refreshing

Power Consumption

Low

High

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