[SI-LIST] Re: Driver slew rates
- From: steve weir <weirsi@xxxxxxxxxx>
- To: ravikumar potluri <potluri.ravikumar@xxxxxxxxx>
- Date: Sat, 23 Nov 2013 09:00:44 -0800
The channel length is electrically about 1.5X as long as the transition
time. That's easily 10X longer than where you can treat the line as
lumped.
The termination set-up of the receiver as it is performing in the
simulation is not matched to the line. Check your model and set-up.
Steve
On 11/23/2013 8:47 AM, ravikumar potluri wrote:
> I am sorry but the time scale in nanoseconds with 8ns cycle time. Yes,
> I think I understand you correctly. The high transition rates indeed
> is the cause for these reflections?. I have already terminated the
> traces internally at the receiver. I think I need an external
> termination too If I am not mistaken.
>
>
> On Sat, Nov 23, 2013 at 5:41 PM, steve weir <weirsi@xxxxxxxxxx
> <mailto:weirsi@xxxxxxxxxx>> wrote:
>
> The time scale is not visible in your traces, but the top trace is
> the result of an unterminated transmission line that is
> electrically long compared to the transition times. The signal
> energy is not being absorbed within the round trip so memories of
> transitions past haunt the present. Change the configuration of
> the receiver input buffer to terminate the signal.
>
> Steve.
>
> On 11/23/2013 8:26 AM, ravikumar potluri wrote:
>> Thank you all very much. Please find the attached figure. I
>> downloaded the IBIS model from TI and spartan websites. Also I
>> used different drive strengths but no improvement.
>>
>> Regards,
>> Ravi
>>
>>
>> On Sat, Nov 23, 2013 at 5:20 PM, bala <balaseven@xxxxxxxxx
>> <mailto:balaseven@xxxxxxxxx>> wrote:
>>
>> Ravi,
>> Pls check driver's input impedance and use low strength model
>> if your tline
>> is short.check your package model too.
>> Regard
>> bala
>> On 23 Nov 2013 21:34, "steve weir" <weirsi@xxxxxxxxxx
>> <mailto:weirsi@xxxxxxxxxx>> wrote:
>> > No.
>> >
>> > Check your models and your simulation set-up.
>> >
>> > Steve.
>> > On 11/23/2013 7:48 AM, ravikumar potluri wrote:
>> > > Hello friends,
>> > > If the slew rate of driver is much higher than the slew
>> rate of receiver
>> > > does this cause reflections on the transmission line?
>> > >
>> > >
>> > > I am simulating ADS62P49, 250 MSPS ADC chip (Driver) with
>> Spartan 3A-DSP
>> > > (Reciever). I see lot of ringing at the output even when
>> the chips are
>> > > connected directly with termination in between and with
>> no transmission
>> > > line.
>> > >
>> > > Could someone explain this?
>> > >
>> > > Thanks and Regards,
>> > > Ravi
>> > >
>> > >
>> > >
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>
>
> --
> Steve Weir
> IPBLOX, LLC
> 1580 Grand Point Way
> MS 34689
> Reno, NV 89523-9998
> www.ipblox.com <http://www.ipblox.com>
>
> (775) 299-4236 Business
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>
> All contents Copyright (c)2013 IPBLOX, LLC. All Rights Reserved.
> This e-mail may contain confidential material.
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> and notify the sender.
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>
--
Steve Weir
IPBLOX, LLC
1580 Grand Point Way
MS 34689
Reno, NV 89523-9998
www.ipblox.com
(775) 299-4236 Business
(866) 675-4630 Toll-free
(707) 780-1951 Fax
All contents Copyright (c)2013 IPBLOX, LLC. All Rights Reserved.
This e-mail may contain confidential material.
If you are not the intended recipient, please destroy all records
and notify the sender.
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