Specifications

48
Page 95
安捷倫科技高頻元件量測研討會
Feb.23, 2006
Differential Return Loss & Reflection Coefficient
Conclusions
-Connectors create large impedance discontinuity
-Daughter card differential impedance is 110 Ω
-Backplane differential impedance is 102 Ω
0 dB--
-50 dB--
20 GHz full scale
Frequency Domain SDD11
1 nsec/div
t = 0
Time Domain TDD11
100 Ω−
80 Ω−
120 Ω−
Page 96
安捷倫科技高頻元件量測研討會
Feb.23, 2006
Single-ended and Differential TDR
t = 0
Single-ended TDR
(NOT odd mode impedance)
50 Ω
1 nsec/div
inside connector
60 Ω
Via fields on either
side of connector
Backplane trace
1 nsec/div
Differential TDR
100 Ω
120 Ω
Coupling brings differential
impedance down