TECHNOLOGY NEWS
A Brief Summary of Recent Research Developments for the Design of Semiconductor Low Noise Amplifiers for Ultra-Wideband Technology
As a result of considerable advantages of ultra-wideband technology (UWB) and the significant advances in radio frequency and monolithic microwave IC design (RFIC and MMIC design) for communications, the need for low noise, low power and high frequency circuits operating in ultra-wide frequency ranges has surged. A key module in UWB RF IC technology is the receiver and an essential constituent of the receiver is the low noise amplifier (LNA). This article presents a brief summary of the latest research developments for semiconductor LNAs along with their advantages and/or drawbacks for UWB. First, a brief overview of UWB is presented followed by a summary of applications and an overview of important LNA design parameters.
Introduction:
Rapid communication has been in existence since the days of classical antiquity. In the early stages of development, it was implemented using means such as light (such as obtained from fire) or smoke in combination with topography and/or manmade structures. These modes of operation were commonly used in military applications. For example, Greek historian and cryptographer Polybius, developed a method using torches in approximately 150 B.C.—a type of semaphore communication—to indicate the contents of a message as well as when a message was ready to be sent and to be received between watchtowers. Semaphore remained the dominant method of rapid relay of information among groups of people until about the 18th century except for the use of carrier pigeons in Asia and the Middle East during approximately 1100-1200s. Close to the mid 1800s semaphore reached its climax with the further development of a system, by Claude Chappe, that was distributed throughout all of France. The next milestone was the first transcontinental telegraph invented by Samuel F.B. Morse and his associates in approximately 1850. It replaced the memorable Pony Express and outdated semaphore. Advances in rapid communications continued and in the 1930s the father of information theory Claude E. Shannon began publishing research in the areas of communications and coding among others, which led to his theorem regarding channel capacity, i.e., C = W [ log2(SNR+1) ]. It is by this formula that we understand that the rate of data transmission in bits/second C, is proportional to the bandwidth W of the channel. Hence, the significance of ultra-wideband technology (UWB).
In 2002 the Federal Communications Commission (FCC) approved the ultra-wideband unlicensed spectrum usages of 1.99-10.6 GHz, 3.1-10.6 GHz and 22-29 GHz for commercial applications. This announcement attracted the interest of both academia and industry leading to a flurry of research in this relatively new domain. In industry, Freescale Semiconductor was the first company to avail itself of UWB: it received the first FCC certification for this technology. Until relatively recently (2002) little has been discussed regarding wideband low noise amplifiers (LNAs). This article will present a brief overview of UWB, its applications, important LNA design parameters and an update on some of the latest developments for semiconductor LNA design for UWB.
Mark S. Hooper
IEEE Consultants' Network of Silicon Valley (IEEE CNSV)
2009 IEEE Santa Clara Valley Circuits and Systems Chapter Chair (IEEE SCV CAS)
(Email: m.hooper@ieee.org)