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7/29/2019 Bctm 06 Sean Slides wergwer ewrgwe ewgwe wergweg
1/19
Sean Nicolson, BCTM 2006
Design and Scaling of SiGe BiCMOS
VCOs Above 100GHz
S. T. Nicolson1, K.H.K Yau1, K.A. Tang1, P. Chevalier2, A. Chantre2
B. Sautreuil2, and S. P. Voinigescu1
1) Edward S. Rogers Sr. Dept. of Elec. & Comp. Eng., Univ. of Toronto2) STMicroelectronics
7/29/2019 Bctm 06 Sean Slides wergwer ewrgwe ewgwe wergweg
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Sean Nicolson, BCTM 2006
Outline
Motivation for W-band SiGe integrated circuits VCO design methodology for low phase noise in W-band
Layout considerations
Measurement results Conclusions and future work
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Sean Nicolson, BCTM 2006
Motivation for W-band SiGe ICs Typical applications: 77GHz auto radar, 94GHz weather radar, imaging
Central to these applications is the low phase noise VCO
Process development: NFmin, Rn & Ysopt difficult to measure in W-band Use VCO as a process monitorfor the noise performance of SiGe technologies
Explore VCO scaling/yield in SiGe
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Sean Nicolson, BCTM 2006
VCO Topology
No cascode
lower phase noise, lower supply voltage
Colpitts topology maximize foscrelative to other topologies
Augment Cbe with Cext Reduces phase noise
Add negative Miller capacitors Increases foscby cancelling Cm
Differential tuning reduces supply induced noise
24mA
CM
VCC
LB
Cext
Cvar
Q1
VTUNE+
VTUNE-LEE
REE CEE
LC
VBB
2.5 V
VTUNE
RB
rpcpbib
E
CB
Cext
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Sean Nicolson, BCTM 2006
W-Band VCO Design Methodology
Use smallest realizable LB with adequate Q
Given fosc, maximize tuning range using large Cext
Negative resistance
Phase noise formula
Phase noise trade-off when HBT pushed to limit
Minimize HBT noise bias at NFmin current density
Maximize Vtankand Cext bias at peak fT current density
22
var
2
2
tank
2
1
1
12
p
p
C
CC
CC
V
IS
ext
ex t
n
out
m
p
p CCCC
CCCC
ext
ex teq
var
var
eqB
oscCL
fp2
1
var2 CVIC
VIRRTCFext
TCBneg
Max. Rnegoccurs at
peak fT/fMAXbias
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Sean Nicolson, BCTM 2006
VCO Fabrication
Fabricated in three technology splits:
All VCO layouts and bias currents are identical no redesign
Directly compare VCOs fabricated in different processes
Use the VCO to optimize HBT profile Noise parameters from phase noise
fMAX from VCO output power
BiC9
fT = 150GHz
fMAX = 160GHz
emitter
45mm0.17mm
BipX
fT = 230GHz
fMAX = 300GHz
emitter
45mm0.13mm
BipX1
fT = 270GHz
fMAX = 260GHz
emitter
45mm0.13mm
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7/19 Sean Nicolson, BCTM 2006
VCO Layout
VCO core area: 100mm 100mm
Spiral inductors where necessary to reduce area Plenty of supply decoupling (MiM and metal-metal)
70mm
100mm
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Technology Overview fT/fMAX Scaling Peak fT/fMAX current density increases at each technology node
0.17mm SiGe JpeakfT = 7mA/mm2 where fT = 150GHz
0.13mm SiGe JpeakfT = 14mA/mm2 where fT = 230GHz (or 250GHz)
Contrast with CMOS
JpfT = 0.3mA/mm, JpfMAX = 0.2mA/mm, JNFmin = 0.15mA/mm for 180-65nm nodes
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Measurement Results
VCO performance comparison in 3 SiGe technologies
Phase noise performance
Temperature testing
Wafer mapping
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Sean Nicolson, BCTM 2006
Performance Comparison Across Technology
LC-oscillator frequency insensitive to technology fT/fMAX
MOS varactors give less phase noise than HBT (CBC
) varactors
Higher fMAX more output power, higher frequency
BipX1 results in lowest phase noise
BiCMOS9
MOS var.
BiCMOS9
HBT var.
BipX
HBT var.
BipX1
HBT var.
Tech. fT/fMAX(GHz)
150/160 150/160 230/300 250/260
Differential Pout
(dBm)
+0.7 -1.3 +2.7 +2.5
SSB PN @
1MHz (dBc/Hz)
-101.6 -80 -98 -101.3
Osc. Freq. (GHz) 96 100 106 104
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Sean Nicolson, BCTM 2006
Phase Noise Performance
Oscillation frequency of 104GHz
Phase noise of 101.3dBc/Hz @ 1MHz offset
90nm CMOS
fT=200GHzfmax=275GHz
fT=175
fmax=275
130nmCMOS
fT=175
fmax=275fT=205
fmax=290
fT=206
fmax=197
fT=150
fmax=160
fT=270
fmax=260
fT=155
fmax=155
fT=230
fmax=300
-110
-105
-100
-95
-90
-85
-80
65 70 75 80 85 90 95 100 105 110
Oscillation frequency (GHz)
Phasenoiseat1MHzoff
s
(dBc/Hz)
Averaged Spectral PlotPhase Noise in W-Band
SiGe VCOs
**References provided in abstract**
FMCW modulation
7/29/2019 Bctm 06 Sean Slides wergwer ewrgwe ewgwe wergweg
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Sean Nicolson, BCTM 2006
Biasing W-Band VCOs for Low Noise
NFmin current density scales with technology and fosc Emitter width J
NFmin
(scales with JpeakfT
)
Frequency JNFmin (gets closer to JpeakfT)
Noise correlation further increases JNFmin [K. Yau, SiRF, 2006]
The B and C shot noise
currents are correlated
1exp2* nCnCnB jqIii
cp bibC
RB
E
B
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Sean Nicolson, BCTM 2006
phase
noise
JNFMIN increases
with frequency
output
power
CM
VCC
LB
Cext
Cvar
Q1
VTUNE+
VTUNE-LEE
REE CEE
LC
VBB
2.5 V
Phase Noise Performance Across Bias What is the minimum phase noise current density in W-band VCOs?
Measure output power and phase noise w.r.t current density (vary VBB
)
Looks like phase noise is minimum at peak fT current density
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Sean Nicolson, BCTM 2006
-6
-4
-2
0
2
92 96 100 104 108
Center frequency (GHz)
Outputpower(dBm)
25C
70C
25C
50C
125C
70C
25C
BiC9
MOS var.BiC9
HBT var. BipX
W-Band Manufacturability Challenges Manufacturability specifications for automotive radar are stringent
Outdoors wide temperature variations
Must last for cars lifetime
Low cost per part requires high yield
Is SiGe on the way to meeting such challenges?
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Sean Nicolson, BCTM 2006
Wafer Mapping BiCMOS9
Wafer 1 2 3 4
Center freq. (GHz) 94.7 94.9 94.9 95.0
Tuning range (GHz) 4.6 4.6 4.6 4.6
Output power (dBm) 0.2 0.7 0.6 0.8
DC power (mW) 133.8 133.2 137.3 132.6
Wafer 1 2 3 4
Center freq. (GHz) 99.6 100.5 100.1 100.5
Tuning range (GHz) 3.4 3.6 3.6 3.7
Output power (dBm) -1.1 -1 -1.4 -0.9
DC power (mW) 133.0 133.0 136.2 132.8
Tested 120 VCOs on 4 wafers
Summary of BiC9 VCOs with MOS varactors (60 dice averaged)
Summary of BiC9 VCOs with HBT varactors (60 dice averaged)
4 VCOs had significantly below average performance (outliers)
2 of the 4 outlier VCOs failed to oscillate entirely
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Sean Nicolson, BCTM 2006
Wafer Mapping BipX
VCO not present
Die not tested
< -98 dBc/Hz
-95 -98 dBc/Hz
-92 -95 dBc/Hz
> -92 dBc/Hz
Oscillation Frequency Phase Noise at 1MHz offset
VCO not presentDie not tested
104.5-105.0 GHz
104.0-104.5 GHz
103.5-104.0 GHz
103.0-103.5 GHz
Wafer flat
Location of
VCO in reticule
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Sean Nicolson, BCTM 2006
Figures of Merit Comparison of our work to other state of the art W-Band VCOs
References [1] Huang P. et al, ISSCC 2006 [2] Kobayashi K. W. et al, JSSC 1999
[3] Tang K. W. et al. CSICS 2006 [4] Huang P. et al, ISSCC 2006
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Sean Nicolson, BCTM 2006
Conclusions
Demonstrated a design methodology for low phase noise in W-Band
VCOs Biasing at JpeakfT minimizes phase noise in W-band VCOs
Performed a direct comparison of identical VCOs fabricated in different
technologies
LC-oscillator frequency is insensitive to technology scaling
Higher fT technology yielded VCO with lower phase noise
Higher fMAX technology yielded VCO with improved output power
Future work is required to fully support these conclusions
Noise figure measurements in the W-Band (correlate to Y-parameter method)
Verify JNFmin in the W-Band and support biasing near JpeakfT for min. phase noise
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Sean Nicolson, BCTM 2006
Technology Overview fT/fMAX Scaling Improvement in peak fT/fMAX has two contributions
Layout stripe contact, decreased emitter width 0.17mm to 0.13m
Vertical profile and processing doping, materials, epitaxy, etc.
How much of the speed improvement is due to each contribution?
Measure the 0.13mm HBT layouts fabricated in the 0.17mm process