This chapter is concerned with techniques for integrated circuit amplifiers, and is written mainly as a tutorial aimed at the practicing engineer. For broadband polar design, it is first important to identify the key difference between lumped and distributed design techniques. At intermediate frequencies, we enter the realms of hybrid lumped/distributed design. Many radio-frequency designs fall into this category, although every day we see new technologies and circuit techniques developed that increase the frequency range for which lumped approaches are possible. It is important to describe at the outset a very useful approximation that will assist in simplifying the high-frequency analysis of some of the amplifiers to be described. The technique is known as Miller’s theorem. Miller’s approximation is often a useful way of simplifying circuit analysis by assuming that the input dominant frequency is given by the simple low-pass RC filter. The chapter considers the high-frequency small-signal performance of the bipolar transistor.