Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Full-digital audio amplifier

Status
Not open for further replies.

jetmarc

Member level 3
Joined
Dec 17, 2001
Messages
54
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,235
audio amplifier pure digital

Hi. I am looking for example designs of full-digital audio amplifiers. I want to use a 250mW speaker with minimum external parts, especially without DAC. There are about 2k FPGA gates available to be dedicated to filtering and PWM. The source quality is mono 8khz 8bit.

Any suggestions?

Marc
 

Burger King

Newbie level 6
Joined
Mar 13, 2002
Messages
14
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
38
I don't know if this could help you. I've found a Xilinx appnote on the implementation of sigma delta converters in FPGA (as far as I know it's the only way to avoid adding an external DAC).



Link: www.xilinx.com/xapp/xapp154.pdf
 

micijanus

Junior Member level 1
Joined
Apr 10, 2002
Messages
16
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
55
http://www.apogeeddx.com is the place to go,
And i would like to see the results of your efforts!
DDX2100 ic (i am looking for spice model)
also look at SA07 ic (spice available)
 

jetmarc

Member level 3
Joined
Dec 17, 2001
Messages
54
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,235
Thanks to both of you for the links. I have ordered samples of the DDX chip.

In fact I have a FPGA available in my circuit but I am a bit worried about the logic area necessary to filter the data. Did any of you actually implement such an amplifier in VHDL? I don't want to dedicate more than 2k gates to the audio (including DMA to fetch data from SRAM).

jetmarc
 

micijanus

Junior Member level 1
Joined
Apr 10, 2002
Messages
16
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
55
Also look at the SA07 @ http://www.apexmicrotech.com/products/index.html
The more expensive 97$ 500KHz SA07 (DDX2100 4$)can take both analog & digital signals directly to the chip - no controller. They give good developement tools. And no values on their poposed PCB - and that is where i need help. The only point that i like more on the DDX is the Damped Ternary Advantage over Binary. But i do not know how to put a spice model together for DDX
THNKS

Uploaded file: SA07 Hi Fidelity AUDIO Amplifier.pdf
 

andy2000a

Advanced Member level 2
Joined
Jul 18, 2001
Messages
597
Helped
14
Reputation
28
Reaction score
8
Trophy points
1,298
Activity points
5,298
what is digital audio Amp ?? look like class-D amplifier
about audio Amp
class A --> good amp but efficiency =25%
class B --> have distrtion on signal =0
class AB --> bias on A<-> B use small bias
class C --> someone said Switch like Amp for RF
class D --> PWM amplifier ??? PWM is digital signal and use bridge + Low pass , it is digital audio Amp
, many toy chips use PWM driver speaker . but quality is poor
 

ynhe

Full Member level 3
Joined
May 28, 2001
Messages
184
Helped
6
Reputation
12
Reaction score
2
Trophy points
1,298
Location
China
Activity points
1,346
Hi
It is impossible to simulate pure digital amp using SPICE.
The pure digital amp like apogee include Interpolation,Noise Shaping etc.
How to simulate using spice?
You may simulate using MATLAB.

The pure digital amp is not class D amp.

ynhe
 

andy2000a

Advanced Member level 2
Joined
Jul 18, 2001
Messages
597
Helped
14
Reputation
28
Reaction score
8
Trophy points
1,298
Activity points
5,298
I know what you said ..
digital amp == AC07 codec ssytem
it is pure digital and AC97 use delta-sigma D/A

deltaSigma A/D --> Nation semi or AnalogDevice have many paper
deltaSigma -> use C or matlab or hspice behavior simulation
but modulator is switch Comparator , it can simulation by spice , you can find many paper about it , but we usually matleb simulation system , hspice only simulation circuit

delta sigma D/A --> use digital filter --> codec analog chip
codec is Low pass filter
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top