The Distributed Half Band Filter (DHBF) is a 'down-convert and decimate' filter, primarily intended for use as the first stage in very high sample rate DSP systems. Data is presented at the DHBF input from a high speed sampling system (typically an A to D and anti-aliasing filter) and the input signal is down-converted to base-band with the frequency range +/- fs/4 (where fs is the input sample rate).
RFEL are also able to provide tailored Third Band filters, and Mth-band filters for applications with specialised sample rate / IF requirements.
Basic DHBF Structure
RF Engines proprietary techniques implement the DHBF architecture onto an FPGA device to optimise speed and silicon usage, depending on the customers design parameters. Half Band Filter characteristics can be specified over a wide range with regard to side-lobe (stop-band) level and filter order. Higher order (sharper) filters will typically increase silicon usage, but the flexible architecture of the DHBF will minimise silicon usage for implementation.
Features
- Proven in Xilinx and Altera devices
- Easy migration to most FPGA Vendors devices and architectures.
- Half band filter can be specified for stop-band attenuation and filter order
- Can be used in critically-sampled or over-sampled systems
- Provides a high performance front-end for the RF Engines PFT or FFT architectures.
- Various data input bit widths can be implemented
- Fully synchronous design.
Applications
- Digital Down Converter replacement
- High Speed front ends