FPGA implementation of a tunable band-pass filter using the "basic heterodyne block"
Dhinesh Sasidaran, Akbar Azam, Karl E. Nelson, Michael A. Soderstrand · 2002
Any band-pass filter may be converted into a tunable filter with a single tuning parameter through the use of a new tunable heterodyne band-pass filter concept in which the frequency of the heterodyne signal is adjusted thereby translating the entire filter transfer function in frequency. If the fixed filter is selected to be a narrow-band band-pass filter, the new tunable heterodyne band-pass filter concept can be used very effectively in the elimination of narrow band interference in wide-band communications or control systems. A single-chip version of this tunable filter can be constructed using a Xilinx Virtex XCV800 chip. The resulting filter is a flexible tunable band-pass filter that can be varied from DC to /spl pi//2 or from /spl pi//2 to it depending on the parameters of the fixed output low-pass filter.