Computer-aided design of high data-rate QAM modem circuits

Computer-aided design tools for high-speed QAM (quadrature amplitude modulation) modems are being developed to allow system level simulation and IC design to be integrated in the same environment. Digital architectures for the modulation and demodulation filters are being exploited to develop functional compilers that allow the IC to be customized to system specifications while automating the architecture generation and layout generation. For example, programs have been developed to synthesize the required Nyquist filters from system specifications, generate the architecture using simulations to determine internal and I/O (input/output) wordlengths, and directly generate the layout using previously published optimization strategies to minimize the area and achieve baud rates as high as 50 MBd for 256-level QAM