Chapter 2 Speci fi cation-Governed Telecommunication and High-Frequency-Electronics Aspects of Low-Noise Ampli

The first part of this chapter focuses on placing millimeter-wave research in the context of telecommunication. The second part focuses more strongly on some high-frequency amplifier electronics that were neglected in Chap. 1. In essence, this chapter aims to illustrate the convergence of communications, circuits and antennas, which is necessary in millimeter-wave LNA research. These apparently unrelated aspects of LNA research can furthermore be treated in a single chapter because they set the research constraints (i.e., result in design specifications). For example, there may be a requirement for a 60 GHz communication network deploying a certain type of modulation, but with a particular gain and noise figure; this, once again, illustrates the multidisciplinary nature of LNA research. This chapter will open Part I of the book, the aim of which is to contextualize the research presented in Part II. It will combine two aspects, both extremely important in research into LNAs. The first part of this chapter will focus on placing millimeter-wave research in the context of telecommunication. The second part of the chapter will focus more strongly on some high-frequency amplifier electronics that were neglected in Chap. 1. In essence, this chapter aims to illustrate the convergence of communications, circuits and antennas, which is necessary in millimeter-wave LNA research [1]. These apparently unrelated aspects of LNA research can furthermore be treated in a single chapter because they set the research constraints (i.e., result in design specifications). For example, there may be a requirement for a 60 GHz communication network deploying a certain type of modulation, but with a particular gain and noise figure; this, once again, illustrates the multidisciplinary nature of LNA research. This chapter is set to complement the fundamental theory of LNAs introduced in Chap. 1. The first part of the chapter starts with the introduction of the concept of wavelength, followed by the analysis of the frequency spectrum and various transmission bands and their implications for transceiver system research. The millimeter-wave portion of the spectrum itself is quite wide and there are a few sub-frequency allocations that are the focus of active research and warrant further discussion. The feasibility of passive component implementations, especially © Springer International Publishing AG 2018 M. Božanić and S. Sinha, Millimeter-Wave Low Noise Amplifiers, Signals and Communication Technology, https://doi.org/10.1007/978-3-319-69020-9_2 29 transmission lines, in each range is investigated further, seeing that the component size is dependent on wavelength. Various digital modulation schemes, commonly used in transceiver systems, are also presented in some detail, since the modulation schemes often steer the direction of research. The first part of the chapter also examines some of the antenna and propagation theory, specifically as applicable to millimeter-waves. A typical LNA connects either directly to the antenna or via a bandpass filter, and needs to amplify extremely weak and noisy signals and an effort thus needs to be made to research the antennas as well to avoid introducing additional attenuation on the receiving antenna. Secondly, a large part of this chapter investigates high-frequency electronics. In general, electronics at high frequencies are treated by means of a two-port analysis. This part of the chapter therefore mostly focuses on the two-port theory as applicable to LNA research. This includes two-port modeling and applicable parameters, which are important for practical LNA analysis. This is then followed by a discussion of the amplifier and LNA fundamentals, but mostly structured from the two-port perspective. This includes various two-port gain equations and the stability of amplifiers. Furthermore, concepts such as two-port impedance matching and biasing are examined to some extent. Another two very important concepts introduced in Chap. 1 will be investigated here in much detail and from the two-port perspective: noise and linearity. 2.1 Frequency and Wavelength Frequency of operation has a major influence on the behavior of passive and active devices and thus on any transceiver component that is built to operate at a certain frequency. Inherently, building LNAs for increased frequencies becomes progressively more challenging. The active device responsible for the gain of the amplifier is the transistor. If one looks at the physical structure of the transistor, it is not difficult to identify a number of parasitic components, primarily capacitors. If these are worked into amplifier gain equations, they result in a frequency response of the amplifier that is not flat over all frequencies, but rather starts decreasing with an increase in frequency. A transistor’s transitional frequency is typically used as the measure of the maximum frequency at which an amplifier can be designed to operate. This chapter will assume that a transistor or a technology is chosen such that an active device has a transitional frequency, which is going to allow operation well into the millimeter-wave range (discussed in the following section); thus the performance of the amplifier is only limited by the performance of the passive components, unless otherwise stated. Of course this is often untrue, but the issue will be deferred until later because active devices and their modeling will be researched in Chap. 3 in great detail. 30 2 Specification-Governed Telecommunication .