Authors - Nagito Ishida, Koji Asami, Shogo Katayama, Anna Kuwana, Haruo Kobayashi
Abstract - This paper describes wideband digital-to-analog conversion circuits (DACs) using frequency interleaving architecture. Along with broadband communication standards, wideband DACs are required for wideband communication device measurement and test equipment. First, we explain the basic configuration and operation of the frequency interleaved DAC (FI-DAC) architecture. There the digital input signal is divided into multiple bands. Then they are de-modulated and provided to several sub-DACs, whose analog outputs are modulated and synthesized to the wideband analog output signal. Note that image components are generated by sub-DACs and modulations, which have to be removed by subband synthesis analog filters. The other fundamental problems of this architecture are signal attenuation by zero-th order hold of each sub-DAC output, phase-nonlinearity characteristic of synthesis analog filters, group delay differences among subband channels, and phase discontinuity between adjacent sub-band channels. We examine compensation methods for these problems, and their effectiveness is confirmed with MATLAB simulation.