ABSTRACT
This chapter deals with the analysis of multistage amplifiers and discusses some important considerations. In the DC analysis and design of directly coupled multistage amplifiers, the interrelationship between the bias points of the consecutive stages makes the design procedure relatively more complicated. The biasing of the circuit strongly depends on the common-mode component of the input, which sometimes contains unwanted and unpredictable variations. In AC mode, the coupling capacitors are replaced with short circuits, connecting the cascaded stages together and carrying the signal from one stage to another. The AC analysis of a multistage amplifier is comprised of two major parts: finding the required specifications of the primitive stages, and properly combining them to obtain the specifications of the whole amplifier. In bipolar technology, a cascode amplifier is a two-stage amplifier with the first stage in common-emitter configuration followed by a common-base stage.
