BIRD95 Analysis Method

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BIRD95 Analysis Method

• Objective match FD response of IBIS to
  transistor buffer
• IBIS and Transistor models analyzed using
  S-parameters
• IBIS model constructed using IBIS Center,
  templates
• C_comp at typical calculated at 0.51 pF
• HSPICE 2005.03, CosmosScope 2004.12 used for
  analysis
• .LIN with 3 P-elements (Ports), each with Zo50 O
• Ports 1, 2 represent pulldown and pullup Z,
  respectively
• Port 3 has a DC bias of 1.8 V, and represents
  supply Z
• Models float 100e6 O resistors connect to
  ideal 0

PU
Port 2
Port 3
IO
Port 1
By Michael Mirmak
PD
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Results - Transistor

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Results 100 PD C_comp

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Results 50/50 PU/PD C_comp

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Model Version 1

• We take data on Port 1, Port 2 and Port 3
• We need Zpdn but do not measure it directly
• Use Z-parameter conversion to obtain RjX series
  RC

PU
WIP!
ZPU
Port2
ZPDN
Port3
IO
ZPD
Port1
PD
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Next Steps

• Build model of transistor impedances
• All three ports are critical!
• Add elements to IBIS model to match transistor
• Ensure split C_comp ratio is set, understood for
  match
• Compare vs. transistor and all-PD C_comp
• Add I-T table behavior
• This will account for crowbar currents
• Use AMS languages to match behavior
• See Arpads VHDL-AMS model results