IPB

Welcome Guest ( Log In | Register )

DAC IV stages
Yahzi
post Feb 20 2013, 18:38
Post #1





Group: Members
Posts: 209
Joined: 21-November 12
Member No.: 104669



How important are DAC IV stages in the design of a DAC? I've heard they can cause audible differences. Is this true? I'm not a DAC designer, but I assume there are those who understand the technical merits. Is it a big deal?
Go to the top of the page
+Quote Post
 
Start new topic
Replies
John_Siau
post Feb 20 2013, 22:02
Post #2





Group: Members
Posts: 84
Joined: 28-July 09
From: Syracuse, NY USA
Member No.: 71848



Designing an I-V converter with a 130 dB SNR is not trivial. Impedances need to be very low, and this puts significant demands on the opamp. The opamp must have very low EIN and must be able to deliver high current drive while maintaining low distortion. There are about 2 opamps that will work in this application. Resistors must be metal film (to keep distortion low).

One complication is that high-frequency switching noise is always present on the current outputs of sigma-delta converters. This high-frequency noise must be bypassed with rather large NPO or COG capacitors before entering the I-V converter.

There are many opportunities to cut costs, and there are many opportunities to make mistakes when designing an I-V conversion stage. The I-V conversion stage may be more important than the choice of conversion IC.


--------------------
John Siau
Vice President
Benchmark Media Systems, Inc.
Go to the top of the page
+Quote Post
Arnold B. Kruege...
post Feb 21 2013, 16:11
Post #3





Group: Members
Posts: 4457
Joined: 29-October 08
From: USA, 48236
Member No.: 61311



QUOTE (John_Siau @ Feb 20 2013, 16:02) *
Designing an I-V converter with a 130 dB SNR is not trivial. Impedances need to be very low, and this puts significant demands on the opamp. The opamp must have very low EIN and must be able to deliver high current drive while maintaining low distortion. There are about 2 opamps that will work in this application. Resistors must be metal film (to keep distortion low).

One complication is that high-frequency switching noise is always present on the current outputs of sigma-delta converters. This high-frequency noise must be bypassed with rather large NPO or COG capacitors before entering the I-V converter.

There are many opportunities to cut costs, and there are many opportunities to make mistakes when designing an I-V conversion stage. The I-V conversion stage may be more important than the choice of conversion IC.


Does one have to design anything? Aren't the application notes reliable? Can't I lift the design of the evaluation board?
Go to the top of the page
+Quote Post

Posts in this topic
- Yahzi   DAC IV stages   Feb 20 2013, 18:38
- - John_Siau   The I-V (current to voltage) conversion stage of a...   Feb 20 2013, 20:48
|- - Soap   QUOTE (John_Siau @ Feb 20 2013, 14:48) Fo...   Feb 21 2013, 03:37
|- - John_Siau   QUOTE (Soap @ Feb 20 2013, 21:37) QUOTE (...   Feb 21 2013, 15:20
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 21 2013, 09:20) QU...   Feb 21 2013, 16:09
- - Yahzi   Thanks for the reply John. I'm getting a few p...   Feb 20 2013, 21:47
- - John_Siau   Designing an I-V converter with a 130 dB SNR is no...   Feb 20 2013, 22:02
|- - Yahzi   But it is largely irrelevant if it is competently ...   Feb 20 2013, 22:28
||- - benski   QUOTE (Yahzi @ Feb 20 2013, 16:28) But it...   Feb 20 2013, 22:44
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 20 2013, 16:02) De...   Feb 21 2013, 16:11
|- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 21 2013, 10...   Feb 21 2013, 16:47
- - John_Siau   Take a look at published specifications for D/A co...   Feb 20 2013, 22:52
|- - saratoga   QUOTE (John_Siau @ Feb 20 2013, 16:52) Ta...   Feb 20 2013, 23:51
||- - John_Siau   QUOTE (saratoga @ Feb 20 2013, 17:51) 80d...   Feb 21 2013, 14:57
||- - saratoga   QUOTE (John_Siau @ Feb 21 2013, 08:57) QU...   Feb 21 2013, 20:00
||- - John_Siau   QUOTE (saratoga @ Feb 21 2013, 14:00) All...   Feb 21 2013, 23:03
||- - saratoga   QUOTE (John_Siau @ Feb 21 2013, 17:03) QU...   Feb 21 2013, 23:23
|||- - John_Siau   QUOTE (saratoga @ Feb 21 2013, 17:23) QUO...   Feb 22 2013, 15:15
||||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 22 2013, 09:15) QU...   Feb 22 2013, 16:33
|||||- - saratoga   QUOTE (scuttle @ Feb 22 2013, 09:49) From...   Feb 22 2013, 17:58
|||||- - scuttle   QUOTE (saratoga @ Feb 22 2013, 16:58) QUO...   Feb 22 2013, 19:01
|||||- - saratoga   QUOTE (scuttle @ Feb 22 2013, 13:01) No. ...   Feb 22 2013, 19:39
||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 13:39) Wel...   Feb 22 2013, 20:13
||||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 14:13) Bo...   Feb 22 2013, 20:36
||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 14:36) Lik...   Feb 22 2013, 20:46
||||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 14:46) QU...   Feb 22 2013, 20:53
||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 14:53) Roc...   Feb 22 2013, 21:13
||||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 15:13) QU...   Feb 22 2013, 21:38
|||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 15:38) The...   Feb 22 2013, 22:21
|||||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 16:21) Bu...   Feb 22 2013, 22:24
|||||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 16:24) QUO...   Feb 22 2013, 22:38
|||||||- - greynol   QUOTE (John_Siau @ Feb 22 2013, 13:38) So...   Feb 22 2013, 22:48
||||||||- - John_Siau   QUOTE (greynol @ Feb 22 2013, 16:48) Is t...   Feb 22 2013, 22:57
||||||||- - greynol   QUOTE (John_Siau @ Feb 22 2013, 13:57) Ye...   Feb 22 2013, 23:05
|||||||- - saratoga   QUOTE (Arnold B. Krueger @ Feb 22 2013, 17...   Feb 23 2013, 04:02
|||||||- - Arnold B. Krueger   QUOTE (saratoga @ Feb 22 2013, 22:02) Loo...   Feb 23 2013, 17:11
|||||||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 23 2013, 11...   Feb 27 2013, 15:10
|||||||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 27 2013, 09:10) In...   Feb 27 2013, 16:30
||||||||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 27 2013, 10...   Mar 4 2013, 17:28
||||||||- - Soap   QUOTE (John_Siau @ Mar 4 2013, 11:28) QUO...   Mar 5 2013, 01:11
|||||||- - Nessuno   QUOTE (John_Siau @ Feb 27 2013, 15:10) Wh...   Feb 28 2013, 13:57
||||||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 22 2013, 15:13) An...   Feb 22 2013, 22:56
||||||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 22 2013, 16...   Feb 22 2013, 23:06
|||||- - greynol   QUOTE (scuttle @ Feb 22 2013, 10:01) That...   Feb 22 2013, 19:42
|||||- - Arnold B. Krueger   QUOTE (greynol @ Feb 22 2013, 13:42) QUOT...   Feb 22 2013, 20:36
|||||- - greynol   QUOTE (Arnold B. Krueger @ Feb 22 2013, 11...   Feb 22 2013, 20:43
||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 09:15) Wr...   Feb 22 2013, 17:48
|||- - scuttle   QUOTE (saratoga @ Feb 21 2013, 22:23) QUO...   Feb 22 2013, 15:49
||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 21 2013, 17:03) QU...   Feb 22 2013, 16:10
||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 22 2013, 10...   Feb 22 2013, 19:41
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 20 2013, 16:52) Ta...   Feb 21 2013, 16:00
||- - John_Siau   QUOTE (John_Siau @ Feb 20 2013, 16:52) Ta...   Feb 21 2013, 18:44
|||- - [JAZ]   QUOTE (John_Siau @ Feb 21 2013, 18:44) sy...   Feb 21 2013, 20:36
|||- - John_Siau   QUOTE ([JAZ] @ Feb 21 2013, 14:36...   Feb 21 2013, 22:49
|||- - [JAZ]   That the usual listening volume of most electronic...   Feb 21 2013, 23:45
|||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 21 2013, 16:49) QU...   Feb 22 2013, 16:27
|||- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 22 2013, 10...   Feb 22 2013, 18:17
|||- - John_Siau   The following quote from NwAvGuy's Sansa Clip+...   Feb 22 2013, 18:32
|||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 12:17) In...   Feb 22 2013, 18:40
||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 12:40) I...   Feb 22 2013, 19:10
||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 13:10) QU...   Feb 22 2013, 19:45
||||- - John_Siau   QUOTE (saratoga @ Feb 22 2013, 13:45) I d...   Feb 22 2013, 20:38
||||- - saratoga   QUOTE (John_Siau @ Feb 22 2013, 14:38) QU...   Feb 22 2013, 20:42
|||- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 22 2013, 12:17) Bu...   Feb 22 2013, 20:58
|||- - saratoga   QUOTE (Arnold B. Krueger @ Feb 22 2013, 14...   Feb 22 2013, 21:07
|||- - Arnold B. Krueger   QUOTE (saratoga @ Feb 22 2013, 15:07) QUO...   Feb 22 2013, 23:01
||- - Ethan Winer   QUOTE (Arnold B. Krueger @ Feb 21 2013, 10...   Feb 21 2013, 20:43
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 20 2013, 16:52) D/...   Feb 21 2013, 16:04
|- - John_Siau   QUOTE (Arnold B. Krueger @ Feb 21 2013, 10...   Feb 21 2013, 16:28
|- - Arnold B. Krueger   QUOTE (John_Siau @ Feb 21 2013, 10:28) QU...   Feb 21 2013, 18:28
- - Yahzi   So your view is that it is a potential issue but i...   Feb 20 2013, 23:09
- - saratoga   I think SNR is probably not the best way to think ...   Feb 22 2013, 00:05
- - greynol   Since when has NwAvGuy been the ultimate arbiter o...   Feb 22 2013, 18:53
|- - scuttle   QUOTE (greynol @ Feb 22 2013, 17:53) Sinc...   Feb 22 2013, 19:08
|- - greynol   QUOTE (scuttle @ Feb 22 2013, 10:08) You...   Feb 22 2013, 19:18
- - greynol   So rockbox uses the analog volume control, which i...   Feb 22 2013, 20:27
- - greynol   1) 6 dB is not 20 dB 2) Downward scaling in order...   Feb 22 2013, 21:30
- - Mach-X   Rather ironic that everybody is rather correct. Th...   Mar 5 2013, 11:47


Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 19th December 2014 - 17:03