Wideband, Bandpass, and Versatile Hybrid Filter Bank A/D Conversion for Software Radio

This paper deals with analog-to-digital (A/D) conversion for future software/cognitive radio systems. For these applications, A/D converters should convert wideband signals and offer high resolutions. In order to achieve this and to overcome technological limitations, the A/D conversion systems should be versatile, i.e., it should be possible to adapt the conversion characteristics (resolution and bandwidth) by software. This work studies and adapts hybrid filter banks (HFBs) in this context. First, HFBs, which can provide a large conversion bandwidth, are extended to bandpass sampling, thus minimizing the sampling frequency. Then, we provide efficient ways of improving the HFB resolution in a smaller frequency band, only by reprogramming the digital part. Moreover, this paper takes into account the main drawback of HFBs which is their very high sensitivity to analog imperfections. Simulation results are presented to demonstrate the performance of HFBs.