Operating and Evaluating Quadrature Modulators for Personal Communication Systems

The quadrature modulator is a fundamental radio component for worldwide digital wireless communication standards such as Global System for Mobile Communications (GSM), Digital Communications Systems—1800 MHz (DCS1800), Digital European Cordless Telecommunications (DECT), American and Personal Digital Cellular (ADC/PDC), Japanese Personal Handy Phone (PHP RCR28). A typical system application and the theory of operation of the quadrature modulator are described along with two practical evaluation methods. Radio system considerations are discussed for the quadrature modulator including phase and amplitude imbalances, DC offsets, time dependent phase errors, modulated carrier harmonics, and nonlinear impairments.

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