RF and Microwave Circuit and Component Design for Wireless Systems

CHAPTER FOUR

Transmitter and Receiver System Parameters

4.1 INTRODUCTION

Any wireless system consists of a transmitter and a receiver. The transmitter delivers the carrier signal modulated by information through an antenna. The receiver recovers the information from the received signal from the antenna. Figure 4.1 shows a typical system developed for GSM mobile communications [1]. The system consists of a modulator, a power amplifier (PA), a synthesizer, an RF low noise amplifier (LNA) and mixer, demodulators, and associated filters and couplers. This chapter will describe various parameters used in transmitter and receiver systems.

4.2 RECEIVER SYSTEM CONSIDERATIONS

The receiver is used to process the incoming signal into useful information, adding minimal distortion. The performance of the receiver depends on the system design, circuit design, and working environment. The acceptable level of distortion or noise varies with the application. Noise and interference, which are unwanted signals that appear at the output of a radio system, set a lower limit on the usable signal level at the output. For the output signal to be useful, the signal power must be larger than the noise power by an amount specified by the required minimum signal-to-noise ratio. The minimum signal-to-noise ratio depends on the application; for example, 30 dB for a telephone line, 40 dB for a TV system, and 60 dB for a good music system.

To facilitate the discussion, a dual-conversion system as shown in Figure ...