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Measuring the Pulse Response of Magnetic Devices. ---transients of transmission line circuits. 2008 奈米暨前瞻光電研討會 自旋電子專題 2008/5/24 彰化師大. Yuen-Wuu Suen ( 孫允武 ) Department of Physics, NCHU. Outline Transmission line basics Step response --- time-domain reflectometry (TDR) measurement - PowerPoint PPT Presentation
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1 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Measuring the Pulse Response of Magnetic Devices
Yuen-Wuu Suen (孫允武 )
Department of Physics, NCHU
---transients of transmission line circuits
2008 奈米暨前瞻光電研討會自旋電子專題2008/5/24彰化師大
2 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Outline
Transmission line basics
Step response --- time-domain reflectometry (TDR) measurement
Pulse response
Time-domain transmission (TDT) measurement
Examples
3 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Transmission line basics
V+
x
I+
V-I-
u=c/n
0ZI
V
I
V
Characteristic impedanceC
LZ 0 Usually, Z0=50.
)()()(
)()()(
xIxIxI
xVxVxV
Ground
Signal
4 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Transmission line basics
Voltage reflection coefficient
Current reflection coefficient
V+
I+
V-
I-
ZL
0
0
ZZ
ZZ
L
LV
0
0
ZZ
ZZ
L
LI
II
VV
I
V
Z0
5 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Step response --- time-domain reflectometry (TDR) measurement
Terminated with Z0
Z0
Z0
V0
x0 /2
Z0
V(0)
t0 t0 T
V()
T=/u
t0 T/2
V(/2)
I(0)
t0 t0 T/2
I(/2)
t0 T
I()
20V
0
0
2Z
V
0
6 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Z0
Z0
x0 /2
Z0
V(x)t=0+
T=/u
20V
0
0
2Z
V
0
I(x)
V(x)t=T- 20V
0
0
2Z
VI(x)
V(x)t=2T 2
0V
0
0
2Z
VI(x)
7 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Step response --- time-domain reflectometry (TDR) measurement
Open circuit
Z0
V0
x0 /2
Z0
V(0)
t0 t0 T
V()
T=/u
t0 T/2
V(/2)
I(0)
t0 t0 T/2
I(/2)
t0 T
I()
20V
0
0
2Z
V
11 IV
0V
2T
2T
3T/2
TDR
8 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Z0
x0 /2
Z0
V(x)t=0+
T=/u
20V
0
0
2Z
V I(x)
V(x)t=T- 20V
0
0
2Z
VI(x)
V(x)t=T+ 2
0V
0
0
2Z
VI(x)
1
1
I
V
V(x)t=3T/2 2
0V
0
0
2Z
VI(x)
V-(x)
I-(x)
9 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Step response --- time-domain reflectometry (TDR) measurement
Short circuit
Z0
V0
x0 /2
Z0
V(0)
t0 t0 T
V()
t0 T/2
V(/2)
I(0)
t0 t0 T/2
I(/2)
t0 T
I()
20V
0
0
2Z
V
2T
2T
3T/2
TDR
0
0
Z
V
11 IVT=/u
10 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Step response --- time-domain reflectometry (TDR) measurement
Capacitive load
Z0
V0
x0 /2
Z0
V(0)
t0 t0 T
V()
T=/u
t0 T/2
V(/2)
I(0)
t0 t0 T/2
I(/2)
t0 T
I()
20V
0
0
2Z
V
0V
2T
2T
3T/2
TDR
11 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Step response --- time-domain reflectometry (TDR) measurement
Inductive load
Z0
V0
x0 /2
Z0
V(0)
t0 t0 T
V()
T=/u
t0 T/2
V(/2)
I(0)
t0 t0 T/2
I(/2)
t0 T
I()
20V
0
0
2Z
V
2T
2T
3T/2
TDR
0
0
Z
V
12 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Step response --- time-domain reflectometry (TDR) measurement
Resistive load
Z0
V0
x0 /2
Z0
V(0)
t0 t0 T
V()
t0 T/2
V(/2)
I(0)
t0 t0 T/2
I(/2)
t0 T
I()
20V
0
0
2Z
V
2T
2T
3T/2
TDR
RL
0
0
ZR
ZR
L
LV
0
0
ZR
RZ
L
LI
V
ZR
R
L
L
0
2
0
2
ZR
V
L
13 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Capacitance and Inductance
Capacitance: any contact pad with changeable electric potential relative to ground.
d d
AC r 0
For SiO2, if d=100 nm, Cox=0.345 fF/um2.For a 100x100um2 pad, C=3.45 pF.At 10 GHz, Xc=1/2fC=4.6.
Inductance: any wire that changeable current being passed through.
I
]1)/2[ln(2
]75.0)/2[ln(2
rLLL
rLLL
ac
dc L and r in cm, and L>>r.
nH
nH
For L=0.5cm, r=0.025mm, Lac=5nH.At 10 GHz, XL=2fL=314.
14 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Pulse response
+V0
V0
tp
tp
-V0
Using linear superposition
15 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Short circuit
Z0
x0 /2
Z0
V(0)
t0 t0 T
V()
t0 T/2
V(/2)
I(0)
t0 t0 T/2
I(/2)
t0 T
I()
20V
0
0
2Z
V
2T
2T
3T/2
TDR
0
0
Z
V
T=/u
Pulse response
V0
16 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Short circuit
Z0
x0 /2
Z0
V(0)
t0 t0 T
V()
t0 T/2
V(/2)
I(0)
t0 t0 T/2
I(/2)
t0 T
I()
20V
0
0
2Z
V
2T
2T
3T/2
TDR
0
0
Z
V
T=/u
Pulse response
V0
17 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Time-domain transmission (TDT) measurement
Z0
Z0
V0
x0 2
Z0
V(0)
t0 t0 2T
V(2)
T=/u
t0 T
V()
I(0)
t0 t0 T
I+()
t0 2T
I(2)
20V
0
0
2Z
V
RL
RL// Z0
IL()
TDR
TDT
0
0
00
00
2//
//
ZR
Z
ZZR
ZZR
LL
LV
VZR
R
VV
L
L
VL
02
2
)1(
0Z
VL
02
2
/
ZR
V
RVI
L
LLL
IL
18 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Time-domain transmission (TDT) measurement
Z0
Z0Z0RLIL
V0
IDC
VDC
with DC biasing circuit
suitable for 4-wire sample
19 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Single-Shot Time-Resolved Measurements of Nanosecond-Scale Spin-Transfer Induced Switching: Stochastic Versus Deterministic AspectsT. Devolder et al, Phys. Rev. Lett. 100, 057206 (2008)
20 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Z0
Z0
x0 2
Z0
t0 2T
V(2)
T=/u
t0 2T
I(2)
RL
RL+Z0
TDT
Equivalent circuit
000
00
2ZR
R
ZZR
ZZR
L
L
L
LV
VZR
ZR
VV
L
L
V
0
0
2
)(2
)1()(
VZR
RV
ZR
VI
L
LL
LL
0
0
2
2
2
2)(
V
ZR
ZV
L 0
0(2)
2
2 V+(2)
V+(2)
21 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Time-Domain Measurements of Nanomagnet Dynamics Driven by Spin-Transfer Torques I. N. Krivorotov et al, Science 14 January 2005 307: 228-231
22 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Microwave-assisted magnetization switching of Ni80Fe20 in magnetic tunneljunctions T. Moriyama et al, APPLIED PHYSICS LETTERS 90, 152503 (2007)
23 Yuen-Wuu Suen (孫允武 )Department of Physics, NCHU
Spin-torque diode effect in magnetic tunnel junctionsA. A. Tulapurkar et al, Nature, Vol 438|17 November 2005|doi:10.1038/nature04207