Performance testing of the North American CDMA system, using an envelope simulator

The growing use of spread spectrum techniques for personal communications (PCS) in Japan and USA is proving to be an enormous stimulus for the study of system impact on component design. New and innovative techniques are required to translate system criteria into component specifications. In this paper we have studied the performance of the “North American Digital Cellular IS-95” system proposed by QUALCOMM, under the influence of spurious signals using the new “Circuit Envelope Simulator” in HP-EESOF´s Microwave Design System, MDS. The implemented functional blocks facilitate the generation of proper (noisy) CDMA (reverse and forward) signals, which are then used to program an arbitrary wave generator in order to create actual test signals. Additionally, these functional blocks can be replaced with equivalent circuits, consisting of passive and active elements, etc. For illustrative purposes, we discuss the application of these signals to two real amplifiers, one linear and one nonlinear. The measured results are critically compared with the simulation results