Digital CMOS Abbreviation I Alphabet Dictionary
If-Else (VHDL)
A conditional statement construct in VHDL, is used within processes. It resembles if-else statements in programming languages and can be used to create latches, registers, or multiplexers. If-else statements can effectively create priority encoders.
Implicit Latch
An unintentionally created latch due to a deficient VHDL conditional statement. It often results from not considering that std_logic can have values other than ‘0’ and ‘1’. Implicit latches can complicate placement and routing unnecessarily. Synthesis tools typically detect and highlight them, although they don’t cause synthesis failure and should be removed.
Impure Function (VHDL)
Unlike pure functions, impure functions in VHDL can have their return values influenced by external factors, such as shared variables or file operations.
Infant Mortality
The initial phase in the lifetime of a system or product, is characterized by a high failure rate. This phase occurs early in a product’s life when uncovered faults are detected, and it ends when the failure rate decreases significantly. Controlling failures during the infant mortality phase is less useful than focusing on extending the useful life of the product.
Ingot
A cylindrical silicon crystal that can be sliced into wafers. These ingots are typically doped and represent a single crystal structure.
Input High Voltage
The higher of the two input voltage levels at which the Voltage-Transfer Characteristic (VTC) of a gate has a slope of -1. This defines the edge of the stable logic ‘1’ input range and is important for determining high noise margins.
Input Low Voltage
The lower of the two input voltage levels at which the VTC of a gate has a slope of -1. This defines the edge of the stable logic ‘0’ input range and helps determine low noise margins.
Instance (VHDL)
In VHDL, an instance represents a specific physical declaration of a component’s existence. It uniquely labels the use of that component and describes how its ports are connected in the port map.
Insulator
Also known as a dielectric, it’s a material with a large bandgap and no suitable dopants. Insulators have low charge carrier concentration and conductivity, with high energy barriers for charge carriers from other materials.
Integrated Circuit
Sometimes referred to as a “die,” it can also describe the die when it’s mounted and packaged. An integrated circuit consists of interconnected electronic components on a single chip.
Interwire Capacitance
The capacitance that exists between two wires, either in the same layer or different layers of an integrated circuit. It doesn’t directly cause delay but can lead to coupling and interference, especially in deeply scaled technologies.
Intrinsic Delay
The delay of a logic gate with zero external loading, considering only its self-loading characteristics. Intrinsic delay is independent of gate size because drive resistance and self-loading scale are oppositely to gate size.
Intrinsic Fermi Level
The Fermi level in pure silicon, which lies slightly off the middle of the bandgap. This offset is due to differences in the effective masses of electrons and holes in silicon.
Intrinsic Silicon
Pure silicon with no dopants or compensation of dopants. In intrinsic silicon, the Fermi level is approximately in the middle of the bandgap, and the number of electrons equals the number of holes.
Inverse Region
A region of operation for Bipolar Junction Transistors (BJTs) where the Base-Emitter (BE) junction is reverse-biased, and the Base-Collector (BC) junction is forward-biased. This region behaves differently from the active region, with low current gain and high base current. It’s rarely used in practice
Inversion Fault
A type of coupling fault in memories where a transition in one memory cell causes another cell’s value to change. This coupling typically occurs in one direction.
Inversion Layer
Refers to the conductive channel that forms between the source and drain in a MOSFET when a strong inversion charge accumulates near the surface. This layer is always covered by a depletion region.
Inversion Mode
A mode of operation in a MOSFET where carriers of the opposite type to the substrate start to accumulate near the surface, creating a conductive path between the source and drain. It allows current flow but can only be entered after the depletion mode, so a depletion layer must blanket the inversion layer.
Ion
A charged particle is formed when an atom gains or loses one or more electrons. Ions are relatively heavy due to their nuclei and have limited mobility in solid materials. They contribute to electric fields but not to current flow in solids due to their mass.
Ion Beam Implantation
A process used to modify the properties of silicon by directing a high-energy ion beam at it. This process is often used to introduce dopants into the crystal structure, and the energy of the beam determines the depth of penetration. Ion beam implantation can create features at specific depths but may require annealing due to crystal structure damage.
Ionization Energy
The energy required to cause a donor dopant to release its extra electron or an acceptor dopant to accept an electron from surrounding silicon. In many cases, thermal energy at room temperature is sufficient to ionize most dopants.
