Under-sampled measurement technique for Hybrid-Filter-Bank characterization in real-time applications

Hybrid Filter Banks (HFBs) are becoming essential systems for several RF applications, such as the development of advanced mixed-domain receivers for Cognitive-Radio scenarios. For the proper design of its digital part, an accurate representation of its analog block transfer function becomes mandatory. In this paper, a new method to measure the response of the HFB Analysis Filter Bank (AFB) is reported. It is based on the acquisition of a comb signal with the HFB analog-to-digital converters (ADCs), and avoids typical imbalance impedance problems involved in its characterization with a Vector Network Analyzer. The usefulness of this technique is experimentally validated in a developed five-channel AFB prototype for the 50-75-MHz band.