bipolar ram
DESCRIPTION
About Bipolar RAM cellsTRANSCRIPT
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DEPARTMENT OF TECHNICAL EDUCATIONANDHRA PRADESH
Name : C.V.S.B.UMA VANIDesignation : LecturerBranch : ECEInstitute : GPW ,Palamaner.Year/semester : III semesterSubject : Digital Electronics Subject code : CM-305Topic : Semiconductor Memories (4/10)Duration : 50 MtsSub Topic : Bipolar RAM CellTeaching Aids : ppt , Diagrams
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OBJECTIVES
On completion of this period you would be able to
• Define the Memory cell.
• Explain the working of basic bipolar RAM cell.
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Recap
In the last class we have studied about
• Static and Dynamic Memories
• Different types of ROM’s.
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Do You Know ?
• What is meant by Static Memory ?
• What is meant by Dynamic Memory?
• What is meant by Sequential Access Memory?
• What is meant by Random Access Memory?
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Memory Cell:
• A memory Cell is the basic unit for storing a
Single bit of information.
• The cells used to construct semiconductor
memories are usually Flip-Flops designed by
using either bipolar or MOS transistors.
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Fig:1 Basic bipolar RAM Storage Cell
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• The basic bipolar RAM storage cell is shown in Fig.1
• In this Flip-Flop one Transistor is ON and the other is
OFF.
• The OFF transistor is forced into ON by an external trigger
pulse, the transistor that was initially ON turns OFF.
• It has two stable states which are used to store
information in the form of logic 0 & 1.
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Fig:2 Bipolar RAM Cell
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• The bipolar RAM cell with required facilities is shown in
Fig.2.
• The Flip – Flop consists of two transistors T1 and T2
with additional emitters for addressing.
• The remaining circuitry for writing &reading the data.
• Signals Ax and Ay are used to address the cell.
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• Let Ax, Ay &W/R inputs at logic 0 the O/P’s of G1 & G2 will be 1, Transistors T3 &T4 ON. D1& D2 are non- conducting.
• The state of Flip-Flop is T1 is ON T2 is OFF.
• Let Ax, Ay &W/R inputs at logic 1.If the data input is at logic 1 the O/P’s of G1 will be 1& G2 will be 0.T3 is ON T4 is OFF.
Hence, the logic level at the collector of T2 will become the logic level of the data input.
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Summary
We have discussed about
• The working of a Basic Memory Cell.
• The working of a Basic bipolar RAM Cell.
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QUIZ(1) A Memory Cell stores
(a) One bit of information
(b) One byte of information
(c) One Nibble of information
(d) None of the above
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(2) A Bipolar RAM Cell is constructed by using
(a) MOSFET’ s
(b) CMOSFET’ s
(c) Bipolar Transistors
(d) None of the above
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QUESTIONS
(1) What is meant by Memory Cell ?
(2) Explain the working of Bipolar RAM Cell.