TABLE OF CONTENTS The history of high-frequency receivers is largely the history of the search for low noise. One of the most important goals and successes of the MIT Radiation Laboratory, during the 1940s, was the improvement of the sensitivity of radar receivers. Throughout the 1960s and 1970s, as space communication matured, the search for low-noise diode mixers became critical. The development of low-noise microwave FET devices, and their improvement to the point of astonishingly low noise figures, was one of the major technological successes of the 1980s and 1990s.
Even though we now have extraordinarily good low-noise transistors, the problem of optimization is just as important as in the past. Indeed, there is no point in incurring the huge expense and effort of developing such devices if designers do not create circuits that realize those devices' potential. This chapter addresses that subject.
In this chapter, we are concerned exclusively with high-frequency noise. Low-frequency noise, both 1/ f and burst noise, although present in the devices we discuss, is invariably too low in frequency to affect high-frequency amplifiers. These noise sources become important in nonlinear circuits, especially oscillators, which we examine in other chapters.
Both bipolar and FET devices are used in high-frequency amplifiers. Homojunction bipolar devices and silicon FET devices are generally suitable for use at frequencies up to a few gigahertz; some advanced technologies, especially short-gate silicon MOS devices, may be useful well into the microwave or even millimeter regions. The minimum noise figures of...
