"BxBChan" Polyphase Filter Bank Channelizer
"BxBChan" Polyphase Filter Bank Channelizer
Bit by Bit Signal Processing (BxB) is proud to provide the BxBChan -- an amazing high-speed digital channelizer. It is targeted at processing the largest signal bandwidths with the highest accuracy in the fewest resources in FPGAs and ASICs.
As a complete and general-purpose channelizer solution, the BxBChan has no competition. Altera has demonstrations of how you can build a channelizer yourself using DSP Builder. AMD/Xilinx has examples of channelizer point solutions they have built. AMD/Xilinx also has hard IP point solutions in some of their latest Versal RF chips. If you're building a radio telescope, there is the academic CASPER project. If you're a major aerospace corporation, your company has its own internal dated heritage solutions. However, no one supplies general purpose channelizer IP.
To get a channelizer before the release of the BxBChan, you needed to already have one, understand the theory to build it yourself, or hire an expert to do it. Now you can buy one off the shelf.
The BxBChan is more efficient and highly optimized than what even an expert can typically build using state-of-the-art tools. It also achieves higher clock speeds and clock margin. To obtain this level of optimization BxB designed its own FFT. It was not obtainable with other available FFT IP cores. For more information, see this Design Comparison Deep Dive.
There are many design parameters that must be selected when specifying and customizing a channelizer. The release package for the BxBChan supports all common parameters values. It also includes performance information that helps you set those parameters. This allows a single BxBChan release to have the customization necessary to meet the needs of a wide variety of applications. For more information on how the BxBChan is customized to meet requirements and the needs of algorithmic performance, clock speed, and resource utilization, see this BxBChan Customization Deep Dive.
Each BxBChan is tested prior to delivery with a range of tests designed to catch any issues. These tests are shipped as part of the release, so customers can reproduce them to verify correct operation in their computing environment. Most tests have graphical outputs, that are human-verifiable and give visual insight into BxBChan operation and performance.
Tests cover not just the delivered System Verilog RTL, but also the synthesized netlist. This checks that Quartus or Vivado correctly interpret the RTL. Surprisingly, this has caught a few bugs in these tools. Netlist testing ensures that none of these bugs affect the delivery.
In addition, BxB has internal tests that are performed on a wide range of different BxBChans. Testing large groups of channelizers with different parameters covers corner cases that might otherwise delay delivery, if they are caught later at delivery time.
For more information on release tests, see the BxBChan Release Test Deep Dive.
BxBChans are delivered in the form of basic System Verilog RTL code. This code is not the encrypted model or netlist that other vendors sometimes provide for their cores. This makes BxBChans easy to work with, so that your design flow is not hindered by licensing issues or incompatibility issues.
BxBChan RTL code is tested to work not just with Altera and AMD/Xilinx tools, but also with the widest variety of free software tools. This ensures that the System Verilog used is of the most commonly supported sort, which will have high compatibility. This gives the highest probability that any internal customer tools will also work with BxBChan RTL code.
Some thought has been put into making the delivered RTL files easy to work with. For management simplicity, there is just one source file, with several accompanying data files. Internal variable names are scrambled to prevent name conflicts if you use multiple BxBChans in your design.
BxBChans are not tied to either Altera or Xilinx. Customers can feel safe that their design can be ported to another FPGA vendor if their business requires it. BxBChans are also designed so that they can be ported to ASIC flows.
The BxBChan ships with a 40-page user guide detailing how to use and operate it.
BxB support is also here to help and to answer questions to make sure that the BxBChan is easily integrated, performs the desired function, operates correctly, and also that it meets your performance goals.
Everything takes time to develop, and early in a development cycle there are always issues. The first BxBChan customer had to put up with a few of these. Every issue that leaked by testing was quickly resolved to their satisfaction. For each of these issues, a new delivery test was added so that the issue doesn't recur. In the most recent release, no new issues have been found, and the BxBChan meets the customer's needs algorithmically, in resources, and in clock speed. The BxBChan's customization options allowed the customer to fit the BxBChan to their needs by adjusting top-level parameters. Resources were significantly reduced over their previous solution, and they were able to increase the dynamic range of their processing.
Some BxBChan sizes require FFTs that are not readily available except from BxB. This can be an advantage for customers who wish to make products that cannot easily be duplicated or products for which compatible knock-offs cannot easily be made. Although using these sizes is unlikely to completely prevent knock-offs, it may add significant roadblocks to their development.
Polyphase Filter Bank (PFB) channelizers such as the BxBChan are highly efficient processing engines with many applications. They break a signal with large bandwidth into small pieces of bandwidth that can be processed individually at lower clock rates. They do this in a highly efficient way, exploiting multiple types of symmetry to reduce filter multiplies, to reduce mixer multiplies, and then to further reduce processing through the efficiency of a Fast Fourier Transform.
This can make many types of signal processing both immensely more efficient as well as immensely more accurate.
The BxBChan is targeted at applications processing large bandwidths at high sampling rates. Whenever the sampling rate is at or higher than the FPGA clock rate, a BxBChan is an excellent choice.
Here are some examples of typical applications:
For an engineer to truly understand some of the benefits of a PFB channelizer, it's important to understand the theory of operation. A derivation of the PFB from first principles can be found here. This shows how the PFB is equivalent to a bank of basebanding mixers and filters, which is a standard structure and a great way to understand its algorithmic performance. This basebanding operation can be made arbitrarily close to perfection by choosing the right filter quality.
The BxBChan is an excellent Polyphase Digital Channelizer. It provides higher numerical performance, lower power, lower resource utilization, and higher clock speeds than other options that you would have to build yourself. It is unmatched in supported features. It is cross-platform, supporting both Xilinx and Altera FPGAs, with a path into ASICs.