Overlay transistor
The overlay transistor (also known as a transistor in overlay technology ) is a special design of a bipolar transistor for high-frequency applications (at that time smaller than one gigahertz ). The special transistor geometry is characterized by a large number of individual emitters, which are "overlayed" by a metal layer, i.e. electrically connected, and thus connected in parallel.
With this arrangement, two major problems of earlier bipolar transistors for high frequency applications could be partially solved:
- the resistances of the base and emitter area and
- the relatively high basic transit time .
Alternative transistor geometries that allow similar improvements are the interdigitated and the matrix types.
The overlay transistor was developed in 1964 by the Radio Corporation of America (RCA) on behalf of the Army Electronics Command in Fort Monmouth , New Jersey, as a direct replacement for electron tubes in electrical power amplifiers in military transmission systems.
Individual evidence
- ^ A b Joseph J. Carr: Microwave & Wireless Communications Technology . Newnes, 1997, ISBN 0-7506-9707-5 , pp. 237 .
- ↑ Sitesh Kumar Roy, Monojit Mitra: Microwave Semiconductor Devices . PHI Learning Pvt. Ltd., 2003, ISBN 81-203-2418-8 , pp. 148 .
- ^ GWA Drummer: Electronic Inventions and Discoveries: Electronics from its earliest beginnings to the present day . 4th edition. CRC Press, 1997, ISBN 0-7503-0376-X , pp. 200 .