[SI-LIST] Re: Minimum length for SERDES
- From: cris_filip2002@xxxxxxxx
- To: "cris_filip2002@xxxxxxxx" <cris_filip2002@xxxxxxxx>, 邱獻民 <gn01216674@xxxxxxxxx>
- Date: Fri, 20 Mar 2015 00:32:21 -0600
DDR3L is not a SerDes IF and the length constraint is related to timing
requirements.
> On Mar 20, 2015, at 12:25 AM, cris_filip2002@xxxxxxxx wrote:
>
> What do you mean by IC spec? IC data sheet? If so what ICs are you referring
> too?
>> On Mar 20, 2015, at 12:15 AM, 邱獻民 <gn01216674@xxxxxxxxx> wrote:
>>
>> In some IC spec, total length of USB3 has the minimum limitation about 3"
>> (max:8"), and also DDR3L DQ/DQS has the minimum limitation about 1050 mils.
>> Does anybody know why?
>> Thanks!
>>
>> Murphy
>>
>> 2015-03-20 13:25 GMT+08:00 <cris_filip2002@xxxxxxxx>:
>>> I haven't seen yet such a requirement in any spec. However if this affects
>>> the IL, RL, ILD, ICR, ICN, COM or eye opening constraints, then you should
>>> consider it.
>>>
>>> Cristian
>>>
>>>> On Mar 19, 2015, at 10:40 AM, Felton, Mickey <mickey.felton@xxxxxxx> wrote:
>>>>
>>>> Should also consider the max voltage output, and the max input voltage
>>>> possible. Too little Insertion loss can lead to clipping.
>>>>
>>>> -----Original Message-----
>>>> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
>>>> On Behalf Of Conrad Herse
>>>> Sent: Thursday, March 19, 2015 11:26 AM
>>>> To: 'balaseven@xxxxxxxxx'; si-list@xxxxxxxxxxxxx
>>>> Subject: [SI-LIST] Re: Minimum length for SERDES
>>>>
>>>> In my experience I've found that, all other things being equal, shorter
>>>> channels will exhibit more return loss than longer channels. So, as Chris
>>>> points out, if you have lots of discontinuities in your channel you could
>>>> have more trouble meeting return loss requirements with your shorter
>>>> channels than with your longer channels.
>>>>
>>>> Conrad
>>>>
>>>>> On 3/19/2015 9:47 AM, Cotton, Chris wrote:
>>>>> Of course, there could be a minimum requirement because the designer only
>>>>> chose to validate signal integrity starting at some given length. But I
>>>>> suspect that what you are really asking is if there is ever a need for a
>>>>> minimum trace length requirement? I believe the answer is yes. For
>>>>> minimum lengths, loss (i.e., insertion loss) will be low. If the driver
>>>>> and/or receiver are mismatched to the channel impedance or if there are
>>>>> significant discontinuities in the channel then reflections may take many
>>>>> roundtrips to dampen and this may wreak havoc on your eye.
>>>>>
>>>>> Chris
>>>>>
>>>>> -----Original Message-----
>>>>> From: si-list-bounce@xxxxxxxxxxxxx
>>>>> [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of bala
>>>>> Sent: Thursday, March 19, 2015 10:36 AM
>>>>> To: si-list@xxxxxxxxxxxxx
>>>>> Subject: [SI-LIST] Minimum length for SERDES
>>>>>
>>>>> Hi all,
>>>>> Is there any minimum trace length requirement for high speed SERDES?if
>>>>> yes, why?
>>>>>
>>>>> Regards
>>>>> bala
>>>>>
>>>>>
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