frequency scaling and topology comparison of millimeter-wave vcos
DESCRIPTION
Frequency Scaling and Topology Comparison of Millimeter-wave VCOs. Keith Tang Steven Leung Nelson Tieu Peter Schvan* Sorin Voinigescu University of Toronto, *NORTEL. Outline. Motivation VCO Design Methodology Frequency Scaling Measurement Summary. Motivation. - PowerPoint PPT PresentationTRANSCRIPT
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University of Toronto 2006 1
Frequency Scaling and Topology Comparison of Millimeter-wave VCOs
Keith TangSteven Leung
Nelson TieuPeter Schvan*
Sorin Voinigescu
University of Toronto, *NORTEL
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University of Toronto 2006 2
Outline
Motivation
VCO Design Methodology
Frequency Scaling
Measurement
Summary
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University of Toronto 2006 3
Motivation
MOSFET DC, HF and noise characteristics are scalable across technology nodesVCO topologies are very simple with one or two transistor half-circuits
Algorithmic design and frequency scaling methodologies can be developed even at 77GHz
→ Design productivity increases!
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University of Toronto 2006 4
Colpitts VCO – Design1. Choose LTANK (smallest for
low phase noise)
2. Calculate Ceq from operating frequency
3. Bias transistors at optimum noise current density (0.15
mA/m)
4. Size transistors to provide enough negative resistance
5. Choose LS large (AC open)
6. Add RSS, CSS and LSS for bias and noise de-coupling
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University of Toronto 2006 5
Cross-coupled VCO – Design
1. Choose LTANK
2. Bias transistors at optimum noise current density (0.15 mA/m)
3. Size transistors to provide enough negative resistance
4. Calculate CVAR from operating frequency
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University of Toronto 2006 6
LTANK
C1
CVAR
Frequency Scaling
LTANK/k
C1/k
CVAR/k
LCfOSC
1
fOSCk
Same applies to cross-coupled VCO
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University of Toronto 2006 7
8 2 1.6
Nf does not scale with L and C at very high frequency because of parasitic gate and source resistances
fOSC drops by 20% in 180-nm VCO due to lack of parasitic extraction tools
VCO Test Structures
Colpitts VCO
90-nm
10 GHz
90-nm
77 GHz
180-nm
20 GHz
180-nm
40 GHz
90-nm
50 GHz
90-nm
80 GHz
LTANK [pH] 435 50 200 100 100 60
C1 [fF] 800 100 100 50 50 35
CVAR [fF] 800 100 100 50 50 35
Wf [um] 1 1 2 2 2 2
Nf 100 60 40 20 20 16
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University of Toronto 2006 8
VCO Test Structures (2)
Cross-coupled VCO
90-nm
10 GHz
90-nm
12 GHz
180-nm
17 GHz
LTANK [pH] 435 273 70
CVAR [fF] 260 260 70
Wf [um] 1 1 2
Nf 24 24 40
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University of Toronto 2006 9
Tuning range:
9.2 – 10.4 GHz (11.8%)
10-GHz Colpitts VCO
Record phase noise:
-117.5 dBc/Hz @ 1 MHz (100 avg.)
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University of Toronto 2006 10
Record tuning range:
73.8 – 80.0 GHz (8.3%)
77-GHz Colpitts VCO
Record phase noise:
-100.3 dBc/Hz @ 1 MHz (100 avg.)20log(8) ≈ 17dB higher than
10-GHz VCO’s phase noise!
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University of Toronto 2006 11
10-GHz Cross-coupled VCO
Phase noise:
-109.2 dBc/Hz @ 1 MHz (100 avg.)
Tuning range:
9.3 – 10.9 GHz (15.8%)
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University of Toronto 2006 12
77-GHz CMOSCross-coupled VCOs
First VCO with p-MOSFET at 77 GHz
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University of Toronto 2006 13
Die Photos77 GHz Colpitts VCO:
0.42mm
0.40mm0.16mm
0.22mm
77 GHz Cross-coupledVCO:
0.37mm
0.27mm0.08mm
0.22mm
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University of Toronto 2006 14
√ ․√ X
At very high frequency…
Topology Comparison
Topology Colpitts Cross-coupled
Power consumption
Tuning range
Output power
Phase noise
At low frequency:
√ √
√ ․
․ √
√ X
√ X
․ √
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University of Toronto 2006 15
Figure of Merit for VCO defined in ITRS 2003:
But, output power is important for mixer, PA…
VCO Figure of Merit
DISS
OSC
PfLf
fFoM
][
12
1
DISS
OUTOSC
PfL
P
f
fFoM
][
2
2
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University of Toronto 2006 16
FoMs Comparison
With FoM2, SiGe HBT VCOs show better performance than CMOS VCOs at mm-wave frequencies
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University of Toronto 2006 17
Summary
VCOs with record-breaking performances achieved by algorithmic design at 10 and 77 GHz
Frequency scaling of Colpitts VCOs from 10 to 77
GHz in 90-nm CMOS, 20 to 40 GHz in 180-nm CMOS demonstrated
First cross-coupled VCO with p-MOSFET at77 GHzColpitts topology exhibits better performances
than cross-coupled topology at mm-wave frequencies
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University of Toronto 2006 18
Acknowledgement
NORTEL and CMC for fabricationCMC for CAD toolsCFI and OIT for test equipmentDr. M. T. Yang for support
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University of Toronto 2006 19
Loss at Very High FrequencyConsidering the transistor’s resistance:
RG, RS increase with frequency and both lumped to RTANK
- Larger transistor size required at very high frequencies
It is critical to keep the VCO layout identical:- Transistor layout- Component orientation- Interconnect routing
such that layout parasitics also scale
fRRN
RR
fNC
SGf
SG
f
,1
,
1,1
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University of Toronto 2006 20
Ref Process fosc
[GHz]
Tuning[%]
Phase Noise[dBc/Hz]
Pout
[dBm]
Pdiss
[mW]
FoM1
[dB]FoM2
[dB]
* 90-nm CMOS:Colpitts
10 12.2 -117.5@1MHz 4.0 36 181.9 185.9
77 8.1 -100.3@1MHz -13.8 37.5 182.3 168.5
* NMOS cross-coupled 10 15.8 -109.2@1MHz -2.2 7.5 180.4 178.2
* CMOS cross-coupled 77 2.6 -84.3@10MHz -13.2 13.5 150.7 137.5
[1] 90-nm CMOS 60 0.17 -100@1MHz -23.2 1.9 192.8 169.6
*[6] SiGe HBT, fT = 170GHz 96 4.6 -101.6@1MHz 0.7 133 180.0 180.7
SiGe HBT, fT = 230GHz 105 4.4 -101.3@1MHz 2.7 133 180.3 183.0
[7] SiGe HBT, fT = 175GHz 77 8.7 -97@1MHz 18.5 1200 163.9 183.0
100 6.2 -90@1MHz 14.3 1200 159.2 173.5
[8] SiGe HBT, fT = 200GHz 75 6.1 -105@1MHz 3.5 72 183.9 187.4
[9] SiGe HBT, fT = 200GHz 98 3.3 -85@1MHz -6 60 167.0 161.0
[10] SiGe HBT, fT = 200GHz 85 2.7 -94@1MHz -8 25 178.6 170.6
[11] InP HBT, fT = 75GHz 108 2.6 -88@1MHz 0.92 204 165.6 166.5
[12] 130nm CMOS 90 2.4 -105@10MHz -16 15.5 172.2 156.2
[13] 130nm CMOS 114 2.1 -107.6@10MHz -22.5 8.4 179.5 157.0
* our work