[SI-LIST] Re: DDR2 in hyperlynx - voltage swing level too high
- From: Allan Wang <allanvv@xxxxxxxxx>
- To: "Beal, Weston" <Weston_Beal@xxxxxxxxxx>
- Date: Mon, 7 Feb 2011 20:15:19 -0500
Doh, I see now.
Thanks. The max speed I'll be using is 200MHz which should make this
easier. It seems to behave just fine without the discrete resistor
too.
Allan
On Mon, Feb 7, 2011 at 7:18 PM, Beal, Weston <Weston_Beal@xxxxxxxxxx> wrote:
> Allan,
>
> The voltage values 0.65 and 1.15 are the switching thresholds in the
> receiver. The actual voltage needs to go beyond these logic thresholds
> for the circuit to work correctly. The simulation results look fine at
> this speed, but will not behave so nicely at the correct speed.
>
> I wonder if you really need the discrete resistor since the receiver
> (DRAM) has on-die termination.
>
> Regards,
> Weston
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Allan Wang
> Sent: Monday, February 07, 2011 3:20 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] DDR2 in hyperlynx - voltage swing level too high
>
> Sorry if this is a bit basic for this mailing list. I'm trying to
> simulate DDR2 terminations according to Altera's external memory
> interface handbook. I can't figure out why my voltage swing is so
> large:
>
> http://i.imgur.com/kCRSE.png
>
> I believe the swing should be 0.65 - 1.15V.
>
> Allan
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