Measurement and Modeling of CMOS Devices in Short Millimeter...

Measurement and Modeling of CMOS Devices

in Short Millimeter Wave Minoru Fujishima

Our position • We are circuit designers. Our final target is not

device modeling, but chip demonstration. Provided device model, if any, is acceptable for us.

• Our approach may not be academic nor deeply considered from physical insight, but pragmatic for our target.

• Today’s presentation is our requisite device modeling in short-millimeter-wave region.

• From the next slide, our position for designing millimeter-wave CMOS circuit will be explained.

2012/9/21 MOS-AK 2

Chip Development Process

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Measurement

Device

Circuit System

Goal of modeling experts

Our goal

General Analog/RF Designers

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Measurement

Circuit System

Device

Designers assume it is device engineers’ duty

Starting point of circuit designer

For Millimeter-Wave Designers

Measurement

Device

Circuit System

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We have to complete every layers.

Customization for millimeter-wave region

(DC model is provided from foundry.)

Millimeter-Wave Design

Measurement

Device

Circuit System

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Bond-Based Design

Use Device Tiles MOSFET Transmission Line Pad etc.

Interface for tiles Transmission Line

No Parasitic Wire Connect No LPE is required

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Measurement

Device

Circuit System

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Accurate Probing

THRU

TL4 TL6

By utilizing scotch tape marker, probing positions are well controlled.

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Measurement

Device

Circuit System

2011/12/9 10 IEEE SSCS DL seminar

will be explained later


Measurement

Device

Circuit System

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Wideband 140GHz CMOS Amp.

M1M2 M3

126µ

112µ

21µ

41µ

63µ 17µ

126µ

56µ

17µ 23µ

56µ

42µ

72fFL/W of MOSFET = 65nm / 22.6µmTransmission line unit : m

M4

40µ

27µ

26µ

M5

23µ

60µ

27µ

M6

17µ

26µ

27µ

M7

60µ

410µ

174µ

Input Output

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Measurement Results

-20-10

01020

Frequency [GHz]

Gain

[dB]

Grou

p Dela

y [ps

]

01020304050

9.7

9.8

9.9

10.0

130 134 142Frequency [GHz]

Gain

[dB]

12GHz

0.1dB

138 146

100 120 140 160 180

Freq. [GHz]

0.1dB-BW [GHz]

3dB-BW [GHz]

Peak Gain [dB]

GD @3dB-BW [ps]

PDC [mW]

Technology [nm]

136.1 12 27.6 9.9 46.2±13.1 57.1 65

Specification Summary

Frequency Characteristics

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Measurement

Device

Circuit System

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135GHzCMOS Wireless TRx Chips Set

15

TX RX

LNA DET Limiting Amp.

Buf

.

RFi

n

BB

out

TRx total power consumption：10Gbps/98.4mW(9.8pJ/bit）

PA-free Tx

Fabricated with 40nm CMOS process

Demonstration of 10cm transmission VLSI Symposium 2012

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Measurement

Device

Circuit System

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Accuracy of PDK model in D band

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110G 130G 150G 170G

110G 130G 150G 170G

S11 S12

S21 S22

Sub-Circuit Extension

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Provided MOSFET model from PDK

Parasitic component to be extracted

Accuracy of sub-circuit extention

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110G 130G 150G 170G

110G 130G 150G 170G

S11 S12

S21 S22

Circuit and Layout Diagram of LNA

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Cascode Amplifier 65nm-CMOS technology Tiles for MOSFETs, transmission lines and pads are used

Measured and Simulated Results

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Gain at 120GHz Simulated : -4.3 dB Measured : -4.9 dB Difference : 0.6dB

S11 S12

S21 S22

110G 130G 150G 170G

110G 130G 150G 170G

Issues in S11 and S22

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Our model

provided MOSFET model

port1 port2

Sub-circuit extension

Cl Cr

Cm

Ll Lr

Sub-circuit topology is firstly decided. Parasitic elements are extracted to fit a measured result including the provided model.

Reflections of the scattering parameters of this model (S11, S22). This model cannot trace all frequencies due to fixed topology.

S11 S22

Measurement Our model

Measurement

Problems of Conventional Way • Applicable frequency range is limited. • All S11, S12, S21, S22 are difficult to fit

simultaneously. • Voltage dependency of parasitic elements

is not considered. • All the physical model in short

millimeter wave is not considered.

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For example: Non-quasi-static (NQS) effect

Vgs

Id

Solution: Matrix-based Model

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Provided I-V model with parasitic C’s

Frequency-dependent admittance matrix

ac simulation

From PDK

S parameters obtained from VNA.

Frequency-dependent admittance matrix

S to Y transformation

From measurement

differentiated Admittance-wrapper model (Y-wrapper model)

No equivalent circuit is assumed

Provided Model and Measured Data

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port1 port2

MOSFET device

ground ground

ground ground provided model of MOSFET in admittance region

port1 port2

Ylogic

Extracted elements in admittance region

Ywrap

distinguish

logicmeaswrap YYY −=

Measured admittance of a device Ymeas

Equivalent Circuit

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port1 port2

y in (v

gs) v1

i1

v2

i2

v1 v2

y rev

erse

(vgs

)

y for

war

d (v g

s)

y out

(vgs

)

Ywrap Vgs Vds

Ylogic

212221121211 ,,, yyyyyyyyyy outforwardreversein +=−=−=+=

After Y-wrapper matrix is extracted, equivalent circuit is determined.

Equivalent circuit with four branches.

Non-Quasi-Static (NQS) Effect

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port1 port2

y in (v

gs) v1

i1

v2

i2

v1 v2

y rev

erse

(vgs

)

y for

war

d (v g

s)

y out

(vgs

)

Ywrap Vgs Vds

Ylogic

y12 and y21 are modeled (wrapped) independently. Even if high-frequency (non-quasi-static: NQS) gm is not considered in the provided model, this wrapper can cover special effects in short millimeter wave.

Voltage Dependence of Parasitics

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0

5

10

15

Im {y

11} [

mS

]

-5

-4

-3

-2

-1

0

Im {y

12} [

mS

]

-16

-12

-8

-4

00 0.5 1

Im {y

21} [

mS

]

Vgs [V]

0

4

8

12

16

0 0.5 1

Im {y

22} [

mS

]

Vgs [V]

20GHz

60GHz

100GHz

20GHz

60GHz

100GHz

20GHz

60GHz

100GHz Measurement Measurement

Measurement Measurement

100GHz

60GHz

20GHz

Bench Mark with Common-Source Amp.

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A pair of matching networks, which are made of transmission lines, are connected to a MOSFET whose gate bias and vdd are fed via the matching networks.

in out

W/L = 32μm/44nm

71.1μm 31.2μm

100.

6μm

101.5μm 55.8μm

73.7μm

75fF

bias vdd

Y-wrapper model of MOSFET

Transmission lines

Capacitor

in out

bias vdd

ground

ground ground

ground

ground

MOSFET Capacitor

One-stage common-source amplifier to verify the Y-wrapper model.

Measurement and Y-wrapper Model

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-40

-30

-20

-10

0

10

-40

-30

-20

-10

0

10



S-p

aram

eter

[dB

] S

-par

amet

er [d

B]

bias = 0.0V vdd = 1.1V




S11

S21

S12

S22

Conclusion • Millimeter-wave designers generally have to

provide device model by themselves.

• Provided PDK can be improved for short-millimeter-wave circuit design. But general sub-circuit extension is not sufficient for short-millimeter wave.

• Matrix-based Y-wrapper can include NQS effect, and is demonstrated for short-millimeter-wave model.

2012/9/21 MOS-AK 31

Measurement and Modeling of CMOS Devices in Short Millimeter...

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