2.1 Introduction

A few years ago, an RF applications/test engineer would have been very focused in this very unique (often termed complex) field, performing tests on discrete RF devices such as mixers, power amplifiers, low noise amplifiers, and RF switches. Today, the test industry faces increasing levels of integration such that many of these discrete device functions are used as building blocks and are contained within one chip or module. Furthermore, the integration levels are such that system-on-a-chip (SOC) devices contain baseband (analog) functionality as well as digital functionality (earlier RF devices often contained three-wire serial communications for controlling things such as gain control, but current digital functionality of these devices is becoming more complex).

Figure 2.1 shows a typical wireless digital radio, which is the foundation for many consumer devices such as mobile phones, cordless phones, pagers, and wireless LAN (WLAN) radios. It is apparent that many components are needed to bring signals into and out of the underlying microprocessor that acts as the brain of the device. While many components make up a complete wireless digital or analog radio as used in today's telecommunications industry, this book will focus on the following:

• RF low noise amplifier (LNA);

• RF power amplifier (PA);

• RF mixer;

• RF switch;

• Variable gain amplifier (VGA);

• Baseband/IF modulator;

• Baseband/IF demodulator;

• Transmitter;

• Receiver;

• Transceiver.

Figure 2.1: Typical wireless radio block diagram.

SOC devices are those that have more than one of the above devices combined on a substrate to provide some function, for example, placing all...