Digital CMOS Abbreviation N Alphabet Dictionary
N-Type Silicon
Silicon in which the concentration of donor impurities exceeds that of acceptor impurities. This results in a surplus of electrons, making electrons the majority of charge carriers. When depleted or biased, n-type silicon forms space-charge regions with positively charged ions
NAND Flash
NAND Flash is a type of Flash memory where the memory cells are arranged in a NAND gate structure. It is similar to NAND ROM in construction and read behavior. NAND Flash is known for its high density, but as the column size increases, its delay also increases. Depletion mode devices are used in NAND Flash, and precise control of threshold voltages is required. Despite these challenges, NAND Flash is a popular choice for mass storage due to its density. Programming and erasing NAND Flash involve Fowler-Nordheim (F-N) tunneling, which affects programming time, erasure time, and write cycles.
Nanotube FET
A variation of FinFETs in which the transistor channel takes the form of a full cylinder. This design allows for maximum gate control, but it lacks mechanical support.
Narrow Channel Effect
An effect was observed in transistors with extremely small channel widths. It is analogous to drain-induced barrier lowering but has a different impact. In narrow channels, parts of the depletion region formed by the gate extend outside the channel region. This excess depletion not contributing to channel formation results in an increase in the threshold voltage.
Negative Bias Instability
The application of a large negative bias voltage on an oxide layer leads to the creation of new trap states within the oxide. These trap states exacerbate the hot carrier effect, causing a rapid drift in threshold voltage. This instability poses a significant reliability concern.
Negative Edge-Triggered Register
A register that transfers input to the output on the falling edge of the clock signal. It typically consists of an active-high master latch followed by an active-low slave latch.
Negative Skew
Skew that occurs when the clock and data signals are driven in opposite directions. Negative skew, while introducing its own challenges, can alleviate hold-time conditions compared to positive skew.
Neighborhood Pattern Sensitive Fault
A complex fault model is often associated with defects in memory cells. In this fault model, the value stored in a cell is affected by specific patterns in neighboring cells. These patterns can be related to the four directly adjacent neighbors or the eight neighbors, including diagonals. The pattern may involve static values or transitions in neighboring cells.
Next (VHDL)
A construct in VHDL is used for loop manipulation. It causes the loop to skip to the next iteration. While not unsynthesizable, it can lead to unpredictable hardware behavior.
NMOS
A type of MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) where the body is p-type (positive), and both the source and drain are n-type (negative). In NMOS transistors, the drain current is carried entirely by electrons.
Noise Margin
The range of acceptable electrical values for a logic input at the input of a logic gate. There are high noise margins for logic “1” inputs and low noise margins for logic “0” inputs. Ideally, the sum of the two noise margins should equal the supply voltage.
Nonvolatile Memory (NVM)
A type of memory that retains its stored data even when the power supply is removed. Nonvolatile memories are also writable or reprogrammable. Unlike volatile memories like SRAM and DRAM, which lose data when power is disconnected, nonvolatile memories are essential for mass storage in modern consumer electronics.
NOR Flash
NOR Flash is another type of Flash memory where the columns form a NOR gate structure. It is similar in construction and behavior to NOR ROMs. NOR Flash is known for its speed but has lower density due to the need for multiple ground lines. It shares the advantages and disadvantages of Flash memories in general. Programming in NOR Flash relies on the hot carrier effect, while erasure is achieved through F-N tunneling. NOR Flash is less commonly used compared to NAND Flash.
NOR ROM
NOR ROM is a read-only memory array where each column of memory forms a NOR gate. The pull-down network (PDN) of the gate is created by the cell transistors. The load can be a gate-grounded PMOS, forming a pseudo-NMOS NOR gate, or more commonly, a precharge PMOS, forming a dynamic gate. Storing a “1” or “0” is determined by the presence or absence of an NMOS transistor in the cell. NOR ROMs are very fast due to the low resistance of the pull-down path but have lower density due to the need for multiple ground lines.
NPN
An npn transistor is a type of Bipolar Junction Transistor (BJT) where the collector and emitter are n-type and the base is p-type. npn transistors have favorable properties because the main charge carrier is electrons, making them commonly used in BJT applications.
Numerical Aperture
Numerical aperture is a representation of the narrowness of a cone of light. It measures how focused light is on the projection surface, particularly at the output of a lens.
