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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 ...
As the electron mobility in the n-type channel of NMOS MOSFETs is about three times that of the hole mobility in the p-type channel of PMOS MOSFETS, NMOS logic allows for an increased switching speed. For this reason NMOS logic quickly began to replace PMOS logic. By the late 1970s, NMOS microprocessors had overtaken PMOS processors. [16]
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.
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.
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 ...
In 1957 Frosch and Derick were able to manufacture PMOS and NMOS planar gates. [17] Later a team at Bell Labs demonstrated a working MOS with PMOS and NMOS gates. [18] Both types were later combined and adapted into complementary MOS (CMOS) logic by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963. [19]
Some authors use the term "complementary pass transistor logic" to indicate a style of implementing logic gates that uses transmission gates composed of both NMOS and PMOS pass transistors. [ 5 ] Other authors use the term "complementary pass transistor logic" (CPL) to indicate a style of implementing logic gates where each gate consists of a ...
PMOS: Mohamed M. Atalla, Dawon Kahng: Bell Telephone Laboratories [2] [3] NMOS: 10,000 nm: 100 nm: PMOS Mohamed M. Atalla, Dawon Kahng: Bell Telephone Laboratories [4] NMOS May 1965: 8,000 nm 150 nm: NMOS Chih-Tang Sah, Otto Leistiko, A.S. Grove Fairchild Semiconductor [5] 5,000 nm: 170 nm: PMOS December 1972: 1,000 nm? PMOS Robert H. Dennard ...