Digital-to-Analog Conversion of Pulse Amplitude Modulated Systems Using Adaptive Quantization

In this paper, a full analysis is presented on digital-to-analog conversion for pulse amplitude modulated (PAM) systems. By analyzing the cyclostationary nature of pulse-amplitude modulation (PAM) systems, two methods of quantization are proposed – fixed and adaptive. Examples of this quantization analysis are provided for the reverse link transmitter chain in a cdma2000 system, and for the baseband transmitter chain of an IS136 system. In addition, the impact of D/A converter nonlinearity on resultant signal-to-noise ratio is analyzed. Simulations are provided which show that adaptive quantization provides performance benefits over fixed methods in terms of adjacent channel power rejection (ACPR) and transmitter signal-to-noise ratio.