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If the MOSFET is an n-channel or nMOS FET, then the source and drain are n+ regions and the body is a p region. If the MOSFET is a p-channel or pMOS FET, then the source and drain are p+ regions and the body is a n region. The source is so named because it is the source of the charge carriers (electrons for n-channel, holes for p-channel) that ...
For many years, NMOS circuits were much faster than comparable PMOS and CMOS circuits, which had to use much slower p-channel transistors. It was also easier to manufacture NMOS than CMOS, as the latter has to implement p-channel transistors in special n-wells on the p-substrate, not prone to damage from bus conflicts, and not as vulnerable to ...
For this reason NMOS logic quickly began to replace PMOS logic. By the late 1970s, NMOS microprocessors had overtaken PMOS processors. [16] PMOS logic remained in use for a while due to its low cost and relatively high level of integration for applications such as simple calculators and clocks.
In PMOS, the polarities are reversed. The mode can be determined by the sign of the threshold voltage (gate voltage relative to source voltage at the point where an inversion layer just forms in the channel): for an N-type FET, enhancement-mode devices have positive thresholds, and depletion-mode devices have negative thresholds; for a P-type ...
1.1 PMOS and NMOS. 1.2 CMOS (single-gate) 1.3 Multi-gate MOSFET (MuGFET) 1.4 Other types of MOSFET. 2 Commercial products using micro-scale MOSFETs.
A transmission gate (TG) is an analog gate similar to a relay that can conduct in both directions or block by a control signal with almost any voltage potential. [1] It is a CMOS-based switch, in which PMOS passes a strong 1 but poor 0, and NMOS passes strong 0 but poor 1.
The NPN BJT (n-type bipolar junction transistor) and nMOS (n-type metal oxide semiconductor field effect transistor) have greater conductance than their PNP and pMOS relatives, so may be more commonly used for these outputs. Open outputs using PNP and pMOS transistors will use the opposite internal voltage rail used by NPN and nMOS transistors.
These were the driving principles in the design of NMOS logic which uses n-channel MOSFETs exclusively. However, neglecting leakage current, unlike CMOS logic, NMOS logic consumes power even when no switching is taking place. The MOSFET invented at Bell Labs between 1955 and 1960, had both pMOS and nMOS devices with a 20 μm process.