Êtes-vous un étudiant de l'EPFL à la recherche d'un projet de semestre?
Travaillez avec nous sur des projets en science des données et en visualisation, et déployez votre projet sous forme d'application sur GraphSearch.
Concept
PMOS logic
Résumé
PMOS or pMOS logic (from p-channel metal–oxide–semiconductor) is a family of digital circuits based on p-channel, enhancement mode metal–oxide–semiconductor field-effect transistors (MOSFETs). In the late 1960s and early 1970s, PMOS logic was the dominant semiconductor technology for large-scale integrated circuits before being superseded by NMOS and CMOS devices.
MOSFET#Early history
Depletion-load NMOS logic#History and background
Mohamed Atalla and Dawon Kahng manufactured the first working MOSFET at Bell Labs in 1959. They fabricated both PMOS and NMOS devices but only the PMOS devices were working. It would be more than a decade before contaminants in the manufacturing process (particularly sodium) could be managed well enough to manufacture practical NMOS devices.
Compared to the bipolar junction transistor, the only other device available at the time for use in an integrated circuit, the MOSFET offers a number of advantages:
Given semiconductor device fabrication processes of similar precision, a MOSFET requires only 10% of the area of a bipolar junction transistor. The main reason is that the MOSFET is self-insulating and does not require p–n junction isolation from neighboring components on the chip.
A MOSFET requires fewer process steps and is therefore simpler and cheaper to manufacture (one diffusion doping step compared to four for a bipolar process).
Since there is no static gate current for a MOSFET, the power consumption of an integrated circuit based on MOSFETs can be lower.
Disadvantages relative to bipolar integrated circuits were:
The switching speed was considerably lower, due to large gate capacitances.
The high threshold voltage of early MOSFETs led to a higher minimum power-supply voltage (-24 V to -28 V).
General Microelectronics introduced the first commercial PMOS circuit in 1964, a 20-bit shift register with 120 MOSFETs – at the time an incredible level of integration.
Source officielle
À propos de ce résultat
Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.