Some question about using FPGA

[Eva Lau]

Hi!
I'm a student and doing a project to construct an Oversampling
Delta-Sigma DAC. I planned to build the system using Cadence, Verilog
HDL and FPGA which are totally new to me, I don't know whether the FPGA
can be programmed to build functions like oversampling and
interpolation, or should I make that part by other electronic components
and connect to the FPGA containing the delta-sigma modulator only?
Hope someone can answer my question. Thanks in advance!

Best Regards,
Eva

 

[Peter Alfke]

Eva, if you can define a purely digital function, then it can be
implemented in an FPGA. The constraints are speed, cost, and power
consumption. But any digital design can fundamentally be implemented in
an FPGA ( and even changed on-the-fly).
Peter Alfke, Xilinx Applications

Eva Lau wrote:

Hi!
I'm a student and doing a project to construct an Oversampling
Delta-Sigma DAC. I planned to build the system using Cadence, Verilog
HDL and FPGA which are totally new to me, I don't know whether the FPGA
can be programmed to build functions like oversampling and
interpolation, or should I make that part by other electronic components
and connect to the FPGA containing the delta-sigma modulator only?
Hope someone can answer my question. Thanks in advance!

Best Regards,
Eva

 

[Xilinx FAE from Insight]

Hi Eva,
You can use AN221E04 from Anandigm.
AN221E04 is a FPAA (Field Programmable Analog Arrays).
Visit www.anadigm.com to know more.

For delta-sigma modulator in digital domain,you may use
a Xilinx FPGA--- Virtex-II family device.

You get a nice programmable system.A convergence of Analog and Digital
programmabilty.
Regards,
SANKET.




Eva Lau <eva_lau@yahoo.com> wrote in message news:<3F6AE6D4.2020500@yahoo.com>...

Hi!
I'm a student and doing a project to construct an Oversampling
Delta-Sigma DAC. I planned to build the system using Cadence, Verilog
HDL and FPGA which are totally new to me, I don't know whether the FPGA
can be programmed to build functions like oversampling and
interpolation, or should I make that part by other electronic components
and connect to the FPGA containing the delta-sigma modulator only?
Hope someone can answer my question. Thanks in advance!

Best Regards,
Eva

 

[Ray Andraka]

Yes, a delta sigma DAC can be done completely in an FPGA. All you need is
an RC filter on the pin. The shortwave radio demo I presented at MAPLD
(block diagram on the top page of my website) uses a pair of delta-sigma
dacs to produce quite good quality sound at a 25KHz sample rate (160 MHz
chip rate). Xilinx has an app-note for one possible design. A delta sigma
ADC, on the other hand requires some analog components to handle the compare
(although that may be able to be done with an LVDS input pair).

Eva Lau wrote:

Hi!
I'm a student and doing a project to construct an Oversampling
Delta-Sigma DAC. I planned to build the system using Cadence, Verilog
HDL and FPGA which are totally new to me, I don't know whether the FPGA
can be programmed to build functions like oversampling and
interpolation, or should I make that part by other electronic components
and connect to the FPGA containing the delta-sigma modulator only?
Hope someone can answer my question. Thanks in advance!

Best Regards,
Eva

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email ray@andraka.com
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

 

[Jim Granville]

Ray Andraka wrote:

Yes, a delta sigma DAC can be done completely in an FPGA. All you need is
an RC filter on the pin. The shortwave radio demo I presented at MAPLD
(block diagram on the top page of my website) uses a pair of delta-sigma
dacs to produce quite good quality sound at a 25KHz sample rate (160 MHz
chip rate). Xilinx has an app-note for one possible design. A delta sigma
ADC, on the other hand requires some analog components to handle the compare
(although that may be able to be done with an LVDS input pair).

Depends on the precision you are chasing.

A straight FPGA pin -> RC will have 50% of the power/ground noise at
idle.
( ie lousy PSRR, and crosstalk) but would be OK for mono shortwave radio
audio.
For higher presisons 12/16/24 bit regions, external TinyLogic Buffer or
analog switches should be used, to 'clean/low noise' +ve/Gnd lines.

Keeps the FPGA for digital stuff, and separate, but very simple parts
for
the analog stuff.

Highest presisions should also use a true integrator, for the charge
balancing.

-jg

Eva Lau wrote:

Hi!
I'm a student and doing a project to construct an Oversampling
Delta-Sigma DAC. I planned to build the system using Cadence, Verilog
HDL and FPGA which are totally new to me, I don't know whether the FPGA
can be programmed to build functions like oversampling and
interpolation, or should I make that part by other electronic components
and connect to the FPGA containing the delta-sigma modulator only?
Hope someone can answer my question. Thanks in advance!

Best Regards,
Eva