Inexpensive solution to double RF bandwidth of vector signal generator

There is a clear tendency to develop upcoming telecommunication applications at increasing RF carrier frequencies. To enable realistic characterizations of RF building blocks, the use of a vector signal generator, enabling modulated excitations, is indispensable. This paper presents an inexpensive way to extend the RF bandwidth of a commercial vector signal generator. The developed set-up consists of a frequency doubler, one or more amplifiers, and the necessary filters. As it is important to control the excitation applied to the circuit-under-test, a predistortion algorithm has been developed. It is shown that the main difficulty is the suppression of unwanted intermodulation products generated by the frequency doubler. The successful implementation is illustrated by the amplitude and phase controllable generation of two-tone signals.