As the operating frequency of communication channels for both video and wireless increases, there is an ever-increasing demand for high-frequency amplifiers. Furthermore, the quest for single-chip integration has led to a whole new generation of amplifiers predominantly geared toward CMOS VLSI. In this chapter, we will focus on the design of high-frequency amplifiers for potential applications in the front-end of video, optical, and RF systems. Figure 5.1 shows, for example, the architecture of a typical mobile phone transceiver front-end. With channel frequencies approaching the 2-GHz range, coupled with demands for reduced chip size and power consumption, there is an increasing quest for VLSI at microwave frequencies. The shrinking feature size of CMOS has facilitated the design of complex analog circuits and systems in the 1-to 2-GHz range, where more traditional low-frequency lumped circuit techniques are now becoming feasible. Since the amplifier is the core component in such systems, there has been an abundance of circuit design methodologies for high-speed, low-voltage, low-noise, and low distortion operation.