CMOS

CMOS emerged because Frank Wanlass realized that pairing opposite transistor types would solve the power consumption problem that made earlier logic impractical for battery-powered devices. His insight—combining p-channel and n-channel transistors in a complementary configuration—created the circuit architecture that powers nearly every modern chip.

Wanlass joined Fairchild Semiconductor in 1962 from the University of Utah. He wanted to use Fairchild's planar manufacturing process to create more stable field-effect transistors, but he faced a fundamental challenge: the n-channel MOS transistors he needed didn't yet exist in reliable form. Undeterred, he pursued a novel approach.

On February 20, 1963, at the International Solid-State Circuits Conference in Philadelphia, Wanlass and co-author C.T. Sah presented their revolutionary finding: logic circuits combining p-channel and n-channel MOS transistors drew close to zero power in standby mode. In demonstrations, their complementary configuration consumed six orders of magnitude—one millionth—the power of contemporary bipolar circuits.

The insight was elegant. In a CMOS gate, only one type of transistor is on at any time. When the circuit is stable, no current flows from power supply to ground. Power is consumed only during switching, and the faster chips switched, the more power they used—but between transitions, a CMOS circuit could sit indefinitely consuming virtually nothing.

Wanlass filed for patent on June 18, 1963. U.S. Patent No. 3,356,858, granted December 5, 1967, described 'low stand-by power complementary field-effect circuitry.' The patent established the foundational architecture that would eventually dominate all semiconductor manufacturing.

Commercializing CMOS took time. RCA pioneered production under the trade name COS/MOS, first for aerospace applications where power consumption mattered critically, then for commercial products. Gerald Herzog led a major CMOS program for an Air Force computer in 1965. By 1968, RCA had introduced the CD4000 family of general-purpose logic devices.

The digital watch was among the first consumer products to exploit CMOS's low power. A watch couldn't be useful if it needed frequent battery changes. CMOS made practical electronics that could run for months or years on a small cell.

By 2011, approximately 99% of all integrated circuits—digital, analog, and mixed-signal—were fabricated using CMOS technology. In 2009, on the 50th anniversary of both the MOSFET and the integrated circuit, Wanlass was inducted into the National Inventors Hall of Fame. The circuit configuration he patented in 1963 had become the default architecture of the digital age. Every smartphone, laptop, server, and embedded system runs on the principle Wanlass demonstrated: pair opposites, and power consumption approaches zero.