[SI-LIST] Re: How to Verify C_comp
- From: "Gregory R Edlund" <gedlund@xxxxxxxxxx>
- To: Timothy.Coyle@xxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Fri, 18 Oct 2002 08:40:03 -0500
Tim,
Can you get inside the HSPICE model and remove the 100 Ohm resistor? If
so, then you can shoot each input pin with a TDR-like step and measured the
area of the reflection. This lab technique published by HP also works in
simulation. I would recommend trying it with a simple capacitor first.
"Measuring Parasitic Capacitance and Inductance Using TDR," David J.
Dascher, Hewlett-Packard Journal, April 1996,
www.hp.com/hpj/apr96/ap96a11.htm.
The "I/O Buffer Accuracy Handbook" has some pointers on this technique,
too. Look at section 3.2.3.
http://www.eda.org/pub/ibis/accuracy/handbook.pdf
Here's a SPICE deck with a simple capacitor:
* TDR capacitance measurement
vin vin 0 pulse 0.0 2.0 1.0ns 0.05ns 0.05ns 10.0ns 20.0ns
rin vin n1 50
tline1 n1 0 n2 0 z0=50 td=1ns
cdut n2 0 2pF
tline2 n2 0 n3 0 z0=50 td=1ns
rt n3 0 50
.tran 0.005ns 5ns
.option csdf
.print tran v(vin) v(n1) v(n2) v(n3)
* Cdut = (2/(Zo*Vinc))*(intvdt)
.meas tran intvdt integ v(n2,n1) from=2.5ns to=4.0ns
.end
Greg Edlund
Senior Engineer
Signal Integrity
IBM Engineering Solution Services
3605 Hwy. 52 N, Dept. HDC
Rochester, MN 55901
gedlund@xxxxxxxxxx
Msg: #9 in digest
Subject: [SI-LIST] How to Verify C_comp
From: "Timothy Coyle" <Timothy.Coyle@xxxxxxx>
Date: Thu, 17 Oct 2002 10:31:26 -0400
Hello,
I have extracted C_comp values for my input and output of my device in
HSPICE. I want to correlate the IBIS file with the C_comp value to the
original HSPICE model
file. What test(s) should I use to test the driver and receiver C_comp
values? This is an LVDS device, so a 100 Ohm termination is required across
the inputs/outputs
for the device to work properly.
Regards,
Tim
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