Designing and Testing Software-Defined Radios

This article reviews the main parts of a software-defined radio (SDR) to emphasize several possible implementations of both receivers and transmitters. We describe solutions for testing and characterizing these types of devices. SDRs typically operate in both the analog and the digital domains, thus mixed-domain instrumentation is necessary to carry out testing. We first give a short overview of several architectures for SDR receiver front ends. Then, several possible architectures for transmitter front ends are described. We discuss methods that can be used to improve amplifier efficiency. Instrumentation currently available in the commercial market that allows the characterization of such types of transceivers is presented.