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Semester 4: M.Sc. Electronics and Communication Semester -IV
CMOS Technology, MOS Transistor, CMOS Logic gates, Physical design
CMOS Technology, MOS Transistor, CMOS Logic Gates, Physical Design
CMOS technology stands for Complementary Metal-Oxide-Semiconductor. It is a technology used for constructing integrated circuits including microprocessors, microcontrollers, and memory chips.
Low power consumption, high noise immunity, and high-density integration.
Used in digital logic circuits, analog circuits, and mixed-signal applications.
MOS transistor stands for Metal-Oxide-Semiconductor Field-Effect Transistor. It is a type of field-effect transistor used for switching and amplifying signals.
There are two types: NMOS and PMOS. NMOS transistors are faster and consume less power when on, while PMOS transistors are slower but can pull up to a high state.
MOS transistors operate by applying voltage to the gate terminal, which creates an electric field that controls the flow of current between the drain and source terminals.
CMOS logic gates use complementary and symmetrical pairs of p-type and n-type MOSFETs to perform logic functions.
Common CMOS logic gates include NOT, AND, OR, NAND, NOR, XOR, and XNOR.
CMOS logic gates are known for their low static power consumption and high scalability.
Physical design refers to the process of transforming a circuit design into a physical layout.
It includes floorplanning, placement, routing, and verification.
Physical design impacts performance, power consumption, and manufacturing yield of VLSI circuits.
VHDL: History, Language elements, entity and architecture declarations
VHDL: History, Language elements, entity and architecture declarations
History of VHDL
VHDL, or VHSIC Hardware Description Language, was developed in the 1980s by the U.S. Department of Defense. Its primary purpose was to document the behavior of ASICs (Application-Specific Integrated Circuits). The language was standardized by IEEE in 1987, which led to its widespread adoption in the design and simulation of digital systems.
Language Elements
VHDL is a strongly typed language that consists of various elements such as data types, operators, and constructs. Key data types include scalar types (e.g., integer, boolean) and composite types (e.g., arrays, records). Operators include arithmetic, relational, and logical operators, which are used to create expressions and manage the data flow.
Entity Declaration
An entity in VHDL defines a hardware component's interface. It specifies the inputs and outputs but does not describe the internal workings. The entity declaration consists of the entity name followed by a port list that details the direction (in, out, inout) and data type of each port.
Architecture Declaration
The architecture in VHDL describes the internal implementation of the entity. It can define how the inputs are processed and how the outputs are generated. The architecture declaration follows the entity declaration and can include concurrent and sequential statements, allowing complex behavior to be modeled effectively.
Modeling Techniques: Behavioral, Data flow, Structural modeling
Modeling Techniques: Behavioral, Data flow, Structural modeling
Behavioral Modeling
Behavioral modeling focuses on describing the functionality of a system. It is used to define how a system reacts to different inputs and conditions. This type of modeling showcases the logic behind a system by using algorithms and signal flow diagrams, enabling designers to visualize and analyze performance before physical implementation.
Data Flow Modeling
Data flow modeling emphasizes the movement of data within a system. It illustrates how data is processed, stored, and transported from one part of the system to another. This technique often employs data flow diagrams (DFDs) to represent sources, destinations, processes, and data stores, ensuring clarity in data governance and integration.
Structural Modeling
Structural modeling deals with the organization of a system and its components. It focuses on the physical relationships between different modules and components and uses techniques such as entity-relationship diagrams (ERD) and Unified Modeling Language (UML) diagrams. This approach allows designers to create a clear blueprint of the system architecture, facilitating the understanding and implementation of system components.
VHDL Statements: Signal assignments, Block statements, Assertion
VHDL Statements: Signal assignments, Block statements, Assertion
Signal Assignments
In VHDL, signal assignments are used to transfer values between signals and variables. The syntax for a signal assignment consists of the signal name, followed by the assignment operator '<=', and the value or expression being assigned. The assignment reflects a change in the signal's value at the next simulation time step, which helps in modeling combinational and sequential logic.
Block Statements
Block statements in VHDL allow the grouping of related declarations and statements. This helps in encapsulating functionality and controlling visibility. Syntax starts with the keyword 'block', followed by declarations and a begin-end structure. Block statements are useful for defining complex architectures and can contain instances of components, signal declarations, and process statements.
Assertions
Assertions in VHDL are used for design verification and debugging. They evaluate logical expressions during simulation and can report failures if conditions are not met. The syntax involves the keyword 'assert', followed by a condition, an optional message, and severity level. Assertions enhance reliability by catching design errors early in the development process.
Advanced VHDL features: Generics, Configuration, Subprograms, Packages
Advanced VHDL features: Generics, Configuration, Subprograms, Packages
Generics
Generics in VHDL allow parameters to be defined at the entity level, enabling flexibility in design. They facilitate code reuse and customization by allowing the same entity to work with different data types and sizes without altering the underlying architecture.
Configuration
Configurations in VHDL provide a way to manage design variations. They allow the specification of component instances and their bindings, enabling different implementations of a design to be used without changing the source code. This is crucial for simulation and synthesis.
Subprograms
Subprograms in VHDL include functions and procedures. Functions are used for computations and return a single value, while procedures can have multiple parameters and do not return a value. They help in structuring code for reusability and maintainability.
Packages
Packages in VHDL allow the grouping of related declarations such as types, subprograms, and constants. This promotes modular design and improves code organization. Packages can be reused across multiple files, enhancing code portability.
