Realization of log-domain high-order transfer functions using first-order building blocks and complementary operators

High-order log-domain filters could be easily designed by using the functional block diagram (FBD) representation of the corresponding linear prototype and a set of complementary operators. For this purpose, lossy and lossless integrator blocks have been already introduced in the literature. Novel first-order log-domain highpass and allpass filter configurations, which are fully compatible with the already published integrator blocks, are introduced in this paper. These are realized using integration and subtraction blocks or a novel differentiation configuration. As a result, a complete set of first-order building blocks would be available for synthesizing any arbitrary high-order transfer function. In order to verify the correct operation of the proposed structures, the performance of the introduced highpass filters was evaluated through simulation results. In addition, a fifth-order log-domain bandpass filter was designed and simulated using one of the introduced first-order highpass filter configurations. Copyright (c) 2006 John Wiley & Sons, Ltd.