Figure 11-1: Tdr Signature Of Shunt Capacitance - Xilinx Virtex-4 RocketIO User Manual

Chapter 11: Design of Transitions
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:
Figure 11-3
reflection, in this case excess capacitance is computed.
246
Td
2Td

Figure 11-1: TDR Signature of Shunt Capacitance

Figure 11-2: TDR Signature of Series Inductance
t2
V
2
∫
C ----------------------------------- - dt
= – ----- -
Z
0
t1
t2
V
∫ tdr
L 2Z ----------------------------------- dt
=
0
t1
shows the integration of the normalized TDR area. Since this is a negative
t
1
Shaded area goes into the
integral for Equation 11-1
Figure 11-3: Integration of Normalized TDR Area
www.xilinx.com
C
t ( ) V
–
tdr step
V
step
t ( ) V
–
step
V
step
t
2
UG072_c3_13_050206
Virtex-4 RocketIO MGT User Guide
UG076 (v4.1) November 2, 2008
R
50Ω
UG072_c3_19_102605
50Ω
UG072_c3_27_102605
Equation 11-1
Equation 11-2