A Bias-Dependent Equivalent-Circuit Model of Evanescently Coupled Photodiode (ECPD) Advisers : J.-...
Transcript of A Bias-Dependent Equivalent-Circuit Model of Evanescently Coupled Photodiode (ECPD) Advisers : J.-...
A Bias-Dependent Equivalent-Circuit Model of Evanescently Coupled Photodiode (ECPD)
Advisers : J.- W. Shi, Y.- J. Chan
Student : Y.- S. Wu
National Central UniversityNational Central University
Micro-Optoelectronic LabsMicro-Optoelectronic Labs
TaiwanTaiwan
IV. Model Extraction
I. Motivation
III. Measurement System
II. The Structure of ECPD
V. The Fitting Results
VI. Conclusions
Outline
IV. Model Extraction
I. Motivation
III. Measurement System
II. The Structure of ECPD
V. The Fitting Results
VI. Conclusions
+
Transmitter for Fiber-Radio Communication System
+ mm-Wave Detector
Photodiode Matching Circuit Antenna
Transmitter Module
The loss of electrical signal can be reduced through wireless
communication system.
To simplify the base station by eliminating the costly post amplifiers
and cables.
+
Transmitter for Fiber-Radio Communication System
+ Mm-Wave Detector
Photodiode Matching Circuit Antenna
Transmitter Module
The loss of electrical signal can be reduced through wireless
communication system.
To simplify the base station by eliminating the costly post amplifiers
and cables.The model extraction of PD serves as a key approach to design the transmitter module
IV. Model Extraction
I. Motivation
III. Measurement System
II. The Structure of ECPD
V. The Fitting Results
VI. Conclusions
Epi-Layer structure
ECPD
Geometric structure
ECPD: Three major target can be achieved simultaneously
Epi-layer structure: Partially p-doped photo-absorption layerGeometric structure: Evanescently coupled waveguide
The ECPD We Used in Our Model Extraction!!
0 10 20 30 40 50-20
-15
-10
-5
0
5
10
-1V -3V -5V
Frequency (GHz)
Rel
ativ
e R
espo
nse
(dB
) Photocurrent: 2mA
Active area: 200m2
Electrical Bandwidth (with Different Reverse Bias )
The measured frequency responses of device A under three different dc bias voltages.
1 10-25
-20
-15
-10
-5
0
5
10
100m2
150m
200m2
DC photocurrent (mA)
40 G
Hz
Outp
ut R
F P
ow
er
(dB
m)
f= 40GHzBias voltage: -5V
(23mA, 6.5dBm)
RF power versus dc photocurrent of ECPD for different reverse at 40GHz.
High Power Performance
IV. Model Extraction
I. Motivation
III. Measurement System
II. The Structure of ECPD
V. The Fitting Results
VI. Conclusions
Heterodyne-Beating Measurement Setup (Large Signal Measurement)
Bias Tee
Mechanical Pump
(fasten the sample)
Power supply & current meter
Polarization controller
EDFA (for high power generation )
Coupler
Polarization controller
Tunable laser
Tunable laser
OM
Power meter
Spectrum (for high frequency 40GHz)
Holder
Piezoelectrical stage
sample
Fiber
electric cord (DC)
electric cord (AC)-
By increasing the wavelength difference, the bandwidth response is available through recording the amplitude of RF tone signal.
Can measure the BW response and power generation
LNA Measurement Setup (Small Signal Measurement)
Port 1
Port 2
EDFA
Power supply
Tunable Laser
Polarization Controller
Polarization Controller
1. Calibrate the packaged Modulator and save as s2p file
2. Don’t change the bias voltage & polarization of the Modulator
3. De-embedded the Modulator
Lightning Network Analyzers
Step 1
Step 2
Modulator
Not only measure amplitude response but also phase response
Anritsu 37300C VNA + MN4765A (commercial PD)
IV. Model Extraction
I. Motivation
III. Measurement System
II. The Structure of ECPD
V. The Fitting Results
VI. Conclusions
Rs
Z=50 ΩCpCsc
Rt
CtCdxCj
L
RC delay time region (fRC)
Space charge screen effect reg
ion (fsc)
The Equivalent Circuit Model
Transit time region (ft)
G=0.013 S
Z=50 Ω
The frequency response can be determined by three major factors
Gang Wang, and Tsuneo Tokumitsu, IEEE Trans. Microwave Theory Tech., 15 (2003) 1227.
Rs
Z=50 ΩCpCsc
Rt
CtCdxCj
L
The Equivalent Circuit Model
G=0.013 S
Z=50 Ω
S22
The components in right hand of the equivalent circuit can be verified by fitting the S22 parameter.
Electrical signal
Electrical signal
Rs
Z=50 ΩCpCsc
Rt
CtCdxCj
L
The Equivalent Circuit Model
G=0.013 S
Z=50 Ω
S22
S21
All the components in the equivalent circuit can be verified by fitting the S21 parameter.
Space charge screen effect region (fsc)
Transit time region (ft)
Optical signal Electrical signal
Rc Contact Resistance
Rj Junction Resistance
Cj Junction Capacitance
Cdx BCB Capacitance
Cp Pad Capacitance
Lg Inductance of Contact Metal
Ls Inductance of Pad
The Definition of Parameters in This Equivalent Circuit
The Step of Model Extraction!!
Part 1 : Determine right hand of equivalent circuit
Measure the S22 parameters of ECPD
Frequency (50MHz to 40GHz)M
easu
red
S22
The Step of Model Extraction!!
Part 1 : Determine right hand of equivalent circuit
Measure the S22 parameters of ECPD
Measure the S22 parameters of
coplanar electrical pad
Frequency (50MHz to 40GHz)
PA
D M
easu
red
S22
The Step of Model Extraction!!
Part 1 : Determine right hand of equivalent circuit
Measure the S22 parameters of ECPD
Measure the S22 parameters of copl
anar electrical pad (L, Cdx, Cp)
Cdx Cp
L
The Step of Model Extraction!!
Part 1 : Determine right hand of equivalent circuit
Measure the S22 parameters of ECPD
Measure the S22 parameters of cop
lanar electrical pad (L, Cdx, Cp)
Perform the I-V measurement
-3 -2 -1 0 1 2
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Cu
rren
t (m
A)
Bias Voltage (V)
I-V Curve
Differential Resistance : 150ohm
The Step of Model Extraction!!
Part 1 : Determine right hand of equivalent circuit
Measure the S22 parameters of ECPD
Measure the S22 parameters of cop
lanar electrical pad (L, Cdx, Cp)
Perform the I-V measurement (Rs)
Rs
The Step of Model Extraction!!
Part 1 : Determine right hand of equivalent circuit
Measure the S22 parameters of ECPD
Measure the S22 parameters of cop
lanar electrical pad (L, Cdx, Cp)
Perform the I-V measurement (Rs)
Perform the C-V measurement (total capacitance)
-3 -2 -1 0-100
-50
0
50
100
150
200
250
Cap
acit
ance
(fF
)Bias Vlotage (V)
C-V Curve
Average Capacitance : 79 fF
The Step of Model Extraction!!
Part 1 : Determine right hand of equivalent circuit
Measure the S22 parameters of ECPD
Measure the S22 parameters of cop
lanar electrical pad (L, Cdx, Cp)
Perform the I-V measurement (Rs)
Perform the C-V measurement (total capacitance)
Cj
The Step of Model Extraction!!
Part 2 : Determine left hand of equivalent circuit
Measure the S21 parameters of ECPD under different
photocurrent and bias voltage 0 10 20 30 40 50
-20
-15
-10
-5
0
5F
req
uen
cy R
esp
on
se (
dB
)
Frequency (GHz)
-1V -3V -5V
Active Area : 150 m2
Photocurrent : 4 mA
0 10 20 30 40 50-20
-15
-10
-5
0
5
F
req
uen
cy R
esp
on
se (
dB
)
Frequency (GHz)
0.2mA 2mA 4mA
Active Area : 150 m2
Bias Voltage : -1 V
The Step of Model Extraction!!
Part 2 : Determine left hand of equivalent circuit
Measure the S21 parameters of ECPD under different
photocurrent and bias voltage
Fit the S21 parameters under high bias voltage and low photocur
rent (Rt, Ct)
Rt
Ct
The Step of Model Extraction!!
Part 2 : Determine left hand of equivalent circuit
Measure the S21 parameters of ECPD under different
photocurrent and bias voltage
Fit the S21 parameters under high bias voltage and low photocur
rent (Rt, Ct)
Fit the S21 parameters under low bias voltage and high photocurrent (Csc)
Csc
IV. Model Extraction
I. Motivation
III. Measurement System
II. The Structure of ECPD
V. The Fitting Results
VI. Conclusions
The Fitting Result of S22 Parameter
The demonstrated model can fit well with the measurement result that obtained under -3V bias voltage with 150 μm2 active area.
0 10 20 30 40 50 60 70-20
-15
-10
-5
0
5
S (-1V) S (-3V) S (-5V)
Fre
qu
ency
Res
po
nse
(d
B)
Frequency (GHz)
M (-1V) M (-3V) M (-5V)
Active Area : 150 m2
Photocurrent : 4 mA
The Fitting Result of S21 Parameter
The space charge screen effect will reduce as the bias voltage increases !!
0 10 20 30 40 50 60 70-20
-15
-10
-5
0
5
S (0.2mA) S ( 2mA) S ( 4mA)
Fre
qu
ency
Res
po
nse
(d
B)
Frequency (GHz)
M (0.2mA) M ( 2mA) M ( 4mA)
Active Area : 150 m2
Bias Voltage : -1 V
The Fitting Result of S21 Parameter
The space charge screen effect is very obvious under low bias voltage and high current generation.
-5 -4 -3 -2 -1-50
0
50
100
150
200
250
Csc (4mA) Csc (2mA) Csc (0.2mA)
Active Area : 150 m2
CS
C (
fF)
Bais Voltage (V)
The Bias & Photocurrent-Dependent Csc Parameter
The device speed performance won’t degrade under high bias voltage as the photocurrent increases due to the elimination of space-charge capacitance.
IV. Model Extraction
I. Motivation
III. Measurement System
II. The Structure of ECPD
V. The Fitting Results
VI. Conclusions
Conclusions
By concerning the relationship between
the influence of bias voltage and
photocurrent in the equivalent circuit-model
of high power PD, such model is more
convenient for systems and circuits
integration especially under high RF power
applications.
0 10 20 30 40 50-20
-15
-10
-5
0
5
Fre
qu
ency
res
po
nse
(d
B)
Frequency (GHz)
Simulated 01mA Simulated 20mA Measured 01mA Simulated 20mA
Active Area : 320 m2
Bias Voltage : -5 V
About 35GHz
freq (40.00MHz to 50.00GHz)
Sim
ula
ted
20
mA
S
(2,2
)S
imu
late
d 1
mA
S
(2,2
)
Frequency (0.0000 Hz to 50.00GHz)
Measu
red
1m
A S
(2,2
)M
easu
red
20
mA
S
(2,2
)
Bias Voltage -5V
J. W. Shi and Y. S. Wu, IEEE Photon. Technol. Lett., 17 (2005) 1929.High-Speed, High-Responsivity, and High-Power Performance of Near-Ballistic
Uni-Traveling-Carrier Photodiode at 1.55m Wavelength
The Model Extraction of BUTC Under High Photocurrent