Xilinx Virtex-5 RocketIO GTP

238 www.xilinx.com Virtex-5 RocketIO GTP Transceiver User Guide
UG196 (v1.3) May 25, 2007
Chapter 13: Design of Transitions
R
The magnitude of this excess capacitance (C) or inductance (L) can also be extracted from
the TDR waveform by integrating the normalized area of the transition’s TDR response.
The respective equations for capacitance and inductance are:
Equation 13-1
Equation 13-2
Figure 13-3 shows the integration of the normalized TDR area.
Figure 13-1: TDR Signature of Shunt Capacitance
Figure 13-2: TDR Signature of Series Inductance
Figure 13-3: Integration of Normalized TDR Area
Td
2Td
C50Ω
UG196_c13_01_051406
50Ω
UG196_c13_02_051406
2
Z
0
------–
V
tdr
t() V
step
–
V
step
-------------------------------------
d
t1
t2
∫
=
2Z
0
V
tdr
t() V
step
–
V
step
-------------------------------------
d
t1
t2
∫
=
t
2
Shaded area goes into the
integral for Equation 13-2
UG196_c13_03_051406
t
1