Abstract

Modulation is one of the fundamental technique required for communication applications. High bit rate, better constellation diagram and effective utilization of bandwidth are the important properties which will be considered in selecting a modulation technique. One such modulation technique which has these properties is QAM technique. Quadrature Amplitude Modulation (QAM) is a combination of two basic modulation techniques amplitude modulation and phase modulation. QAM is widely used in communication applications which come under radio frequency range (such as modems over telephone lines, satellite communications, HD television broadcasting and wireless communications etc) because of its high bit rate, better constellation diagram and effective utilization of bandwidth. Different types of QAM techniques are studied. Designing and implementation of different types of QAMs (16, 32 and 64-QAM) are carried out. In these QAM designs the basic components used are the MOSFETs. The circuit is analyzed at each stage and resulting waveforms are obtained. The bit rate of each QAM is calculated and the comparison is done for different QAMs that are designed. The whole design and implementation of these circuits are carried out using cadence virtuoso software, stimulations are done using spectre circuit simulator and the technology used is CMOS 180nm.