Which kit for DSP on FPGA is better?

kit for DSP on FPGA

Hi,

I'm trying to find kit for reaserch in subject: DSP on FPGA. I have some expierience with Signal Processors, but FPGA is new for me. I've looked on Xilinx and Altera sites and kits which are interesting for me are:

DSP Development Kit, Stratix Edition
https://www.altera.com/products/devkits/altera/kit-dsp_stratix.html

and

XtremeDSP Development Kit
https://www.xilinx.com/ipcenter/dsp/development_kit.htm

Kits looks very similar, FPGAs are also very similar and price looks the same, but ... What with software? What with IPs? It is possible to say which kit is better? Is better for what ...? For general purpose DSP and academic use. Maybe you know some better kits?

Mickey

Re: kit for DSP on FPGA

I think some of these questions are best answered directly by the FPGA companies since you are looking to buy hardware. I'm sure their sales will jump on your inquiry. And if you are using this for educational purposes, they may even have a special discount.

Xilinx and Altera are two direct competitors fighting for almost identical markets. This may be why you are seeing similiar products. Whether their products are mature, that's another question. It looks to me that these tools are fairly new but Xilinx has better documentation. If you are working under lack of technical support, that's probably more of a concern for your decision.

As to which company will produce higher DSP performance FPGAs, I'd say they are probably about the same. This is because Xilinx licenses IPs from 3rd party vendors and pretty much all of those vendors make IPs for both Xilinx and Altera. The performance of your FPGA will also depend on the FPGA synthesis tool. And guess what, the EDA company supports both Xilinx and Altera.

One more thing you might want to pay attention to is the analog IO - driven by your application. Altera seems to have faster ADC:
- 2-channel, 12-bit, 125 million samples per second (MSPS) (A/D)
- 2-channel, 14-bit, 165 MSPS digital-to-analog (D/A)
But Xilinx has higher ADC resolution.
- Two ADC channels: AD6644 ADC (14-bits up to 65 MSPS)
- Two DAC channels: AD9772A DAC (14-bits up to 160 MSPS)
Either board is over-specified even for video applications. It totally depends on your end application. If speed is not your concern, I'd go with Xilinx because the extra bits of input ADC resolution is a plus.

MGPC

Re: kit for DSP on FPGA

Are schematics of these board available, particularly the Xilinx implementation?

What company makes the ADCs and DACs for Xilinx?

- Jayson

Re: kit for DSP on FPGA

The company that makes the ADCs and DACs for the XtremeDSP kit is Analog Devices (ADI) ADC - AD6644(5) and DAC - AD9772A. You can find this information on-line in the XtremeDSP sell sheet:

• https://www.xilinx.com/ipcenter/dsp/xtremedsp_sell_sheet.pdf

The XtremeDSP kit is based on Dime-II module which is made by Nallatech. For the XtremeDSP, Xilinx works with 3rd party vendors to create a development platform. A list of 3rd party vendors that Xilinx uses is available at:

• https://www.xilinx.com/ipcenter/dsp/dsp_dev_brds.htm

If you are looking for different boards with different performance, I'd suggest contacting the 3rd party vendors directly.

MGPC

Re: kit for DSP on FPGA

Do any of these boards use bandwidth limiting (such as a low-pass filter) at the analog input to the ADC?

- Jayson

Re: kit for DSP on FPGA

Jayson said:

Do any of these boards use bandwidth limiting (such as a low-pass filter) at the analog input to the ADC?

- Jayson

Click to expand...

Yes. Bandwidth limited, low-pass filtered, or "spectrally windowed". They are all the same. The latter term is from the data-sheet download link from the URL:
**broken link removed**

I thought this data sheet would reflect more on the board but it's pretty much all about the ADCs and DACs and their performance.

MGPC

Re: kit for DSP on FPGA

In general should all DSP applications use a bandwidth limited ADC or can it be done without? After isn't that what the DSP itself should do?

- Jayson

Re: kit for DSP on FPGA

Jayson said:

In general should all DSP applications use a bandwidth limited ADC or can it be done without? After isn't that what the DSP itself should do?

- Jayson

Click to expand...

My interpretation of bandwidth limited ADC is an ADC that takes an analog signal that has already been filtered by an analog low-pass filter, or so called anti-aliasing filter. The reason this filter is needed is to prevent high frequency signals from aliasing into the lower frequency spectrum where the desired signal exists.

For example, suppose the sampling rate of the ADC is 60 MSPS. Then to prevent aliasing, the desired signal must have a bandwidth less than 30 MHz or else it will be distorted. Suppose the signal you provide to the band-limited ADC can never exceed 30 MHz, then the low-pass filter will not harm your signal (much - but the effect of the low pass filter can be compensated in the digital domain). However, suppose an unintended signal is introduced to your desired signal that exceeds 30 MHz, then this signal will distort your desired signal if a low-pass filter does not exist.

Look at this another way, suppose your desired signal is only 44 kHz and you used a 60 MSPS ADC, then you are essentially "over-sampling" the desired signal. You wouldn't need to digitally compensate for the anti-aliasing filter since it is practically flat at such low frequency. And if some unwanted signal, say at 1 MHz, was introduced, that'll get sampled in. In this case, you will need a digital low pass filter to remove the undesired signal.

Why is over-sampling important in some applications, you might ask? Well, because you can design a really simple low-pass filter, one that may not be spectrally flat up to the cut-off frequency, and you will still get a relatively flat spectrum up to 44kHz. This can save you some money and effort. This info is for those who are designing the anti-aliasing filter + ADCs. On the other hand, if you bought a DSP board with an ADC, then they have already designed a very sophisticated anti-aliasing filter that is close to ideal low-pass filtering up to half the sampling frequency (30 MHz).

So the answer to your question would be yes, all ADCs must be accompanied by an anti-aliasing filter to prevent aliasing. However, whether this anti-aliasing filter will affect your digital filter design, that is a design decision you must make.

MGPC

kit for DSP on FPGA

i hav a A TO D convertor AD6645 but i dont want to use fifo kit with ad6645 and i want to see my IF in matlab any sentiment plzzzzzzzz