Revista: IEEE Transactions on Circuits and Systems II. Express Briefs. Vol. 58, No. 3, pp. 129-133, March 2011.

Autores: J.M. Muñoz-Ferreras, R. Gómez-García, and F. Pérez-Martínez.

The placement of the analog-to-digital converter as near the antenna as possible is a key issue in the software-defined
radio receiver design. Direct sampling of the incoming filtered signal is a compact solution enabling channel simultaneity. In this brief, in the context of evenly spaced equal-bandwidth multiband systems, sufficient conditions for the channel allocation assuring that the minimum sub-Nyquist sampling frequency does not imply aliasing are provided. Subsequently, as a validation example, the design of a minimum-sampling-frequency acquisition system for quad-band applications within a ultrawideband frequency range is shown. Moreover, an innovative solution for its radio-frequency
front end, basically consisting of a signal-interference multiband bandpass filter, is reported. Experimental results of the
built microstrip-filter prototype for the proposed 1–3-GHz-range quad-band system are also given.