Slide 115th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

L-2L De-embedding Method

with Double-T-type PAD Model

for Millimeter-wave Amplifier Design

Seitaro Kawai, Korkut Kaan Tokgoz, Kenichi Okada,

and Akira Matsuzawa

Tokyo Institute of Technology, Japan

Slide 215th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Outline

Background, Motivation

L-2L De-embedding

Conventional PAD models

Proposed 3 parameters PAD model

- Transmission Line

- 1-stage Amplifier

Conclusion

Slide 315th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Motivation

60GHz Gbps wireless communication

IEEE 802.11ad specification

57.24GHz – 65.88 GHz

2.16GHz/ch x 4ch

10.56Gbps/ch in 64QAM

64QAM x 4 channles x 8MIMO 300Gbps

57 58 59 60 61 62 63 64 65 66

240MHz

120MHz

1 2 3 4

1.76 GHz

2.16 GHz

Freq

(GHz)

Slide 415th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

60GHz CMOS Transceiver

PA

Q MIXER

I MIXER

LO BUF.

LO BUF.

Q.OSC.

Logic

PLL

LNA

I MIXER& RF amp

LO BUF.

LO BUF.

Q.OSC.

RX

BB

ou

tT

Xo

ut

RX

in

TX BB in4.2mm

Area

TX 1.03mm2

RX 1.25mm2

PLL 0.90mm2

Logic 0.67mm2

CMOS 65nm, 1Al+11Cu

TX: 186mW

RX: 155mW

PLL: 64mW

Q MIXER& RF amp

Data rate : 28Gbps

[1] K. Okada, et al., ISSCC2014

Slide 515th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Circuit Components in mmW

IN OUT

TL(Branch)Tr.MOM Cap.

TL(Bend)

TL for bias(R=5kΩ)

TL

Slide 615th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

TL Structure

15um

2.5umM9

6.25um1um

7.25um

M1M2 SHIELD

M8

3.875um

3.3

4u

m

2.5um 6.25um 2.5um 7.25um

15um1um

2.5

um

ー M1-M8，ー M9

1um

Slide 715th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

De-embedding

DUT

PAD

Parasitics

Measurement results include PAD, TL.

These components should be removed.

De-embedding is the first step.

Affect to modeling of all components.

Slide 815th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

L-2L Method

TL+PAD = TLPAD TL TRPAD

length = L length = 2L

T2L+PAD = TLPAD T2L TRPAD

(T2L = TL2)

TL+PAD T2L+PAD-1 TL+PAD = TLPAD TRPAD

Canceled Canceled

TL+PAD TL+PADT2L+PAD-1

X X =

[2] J. Song, et al., EPEP2014

Slide 915th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Problems

𝒁𝐬𝒁𝐬𝟐

𝒀𝐬

𝒁𝐬 𝒁𝐬𝟐

𝒀𝐬

TLPADTRPAD

TLPAD TRPAD is symmetric because TL is symmetric.

T11=T22, T12=T21

Only 2 parameters can be obtained.

TLPAD , TRPAD are not symmetric.

3 parameter model should be needed.

Ideal model

Slide 1015th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Problems

30

35

40

45

50

55

60

65

70

75

80

0 10 20 30 40 50 60 70 80 90 100 110

π-equivalent

T-equivalent

Frequency [GHz]

Imp

ed

an

ce[Ω

]

𝒁𝟎 =𝑹 + 𝒋𝝎𝑳

𝑮 + 𝒋𝝎𝑪≈

𝑳

𝑪

(𝝎𝑳 ≫ 𝑹,𝝎𝑪 ≫ 𝑮)

𝒁𝐬′

𝒀𝐬′

𝒁𝐬′

𝒀𝐬′

DUT

T-type

𝒁𝐬′′

𝒀𝐬′′

𝒁𝐬′′

𝒀𝐬′′

DUT

π-type

Slide 1115th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Problems

𝑭𝐓𝐋′ =

𝐜𝐨𝐬𝐡𝜸ℓ𝒁𝟎

(𝒀𝐒𝒁𝐒𝟐 + 𝟏)𝟐𝐬𝐢𝐧𝐡𝜸ℓ

(𝒀𝐒𝒁𝐒𝟐 + 𝟏)𝟐

𝒁𝟎𝐬𝐢𝐧𝐡𝜸ℓ 𝐜𝐨𝐬𝐡𝜸ℓ

𝒁𝐬𝒁𝐬𝟐

𝒀𝐬

𝒁𝐬 𝒁𝐬𝟐

𝒀𝐬is

𝒁𝐬′

𝒀𝐬′

𝒁𝐬′

𝒀𝐬′de-embedded by

When

Slide 1215th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

𝒁𝐬′′

𝒀𝐬′′

𝒁𝐬′′

𝒀𝐬′′

Problems

𝒁𝐬𝒁𝐬𝟐

𝒀𝐬

𝒁𝐬 𝒁𝐬𝟐

𝒀𝐬is

de-embedded by

When

𝑭𝐓𝐋′′ =

𝐜𝐨𝐬𝐡𝜸ℓ 𝒁𝟎(𝒀𝐒𝒁𝐒 + 𝟏)𝟐𝐬𝐢𝐧𝐡𝜸ℓ𝟏

𝒁𝟎(𝒀𝐒𝒁𝐒 + 𝟏)𝟐𝐬𝐢𝐧𝐡𝜸ℓ 𝐜𝐨𝐬𝐡𝜸ℓ

Slide 1315th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Capacitance of PAD affects to impedance.

Capacitance is because of top-metal to ground.

It should be constant in high frequency.

Problems

20

22

24

26

28

30

32

34

36

0 10 20 30 40 50 60 70 80 90 100 110

π-type

T-type

Frequency [GHz]

Cap

acit

an

ce [

pH

]

Slide 1415th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Proposed PAD Model

𝒁𝐬𝒁𝐬𝟐

𝒀𝐬

𝒁𝐬 𝒁𝐬𝟐

𝒀𝐬

It is impossible to get 3 parameter from L-2L.

Assumption:𝒁𝐒𝟐 = 𝒌 × 𝒁𝐒(𝟎 ≤ 𝒌 ≤ 𝟏)

Set “k” to be the PAD capacitance constant.

(In this time, k=0.4)

20

22

24

26

28

30

32

34

36

0 10 20 30 40 50 60 70 80 90 100 110

π-type

T-type

Double-T-type

Slide 1515th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

De-embedding Results of TL

Slide 1615th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Simulation Comparison

0

2

4

6

8

10

40 50 60 70 80

Frequency[GHz]

S21[d

B]

S11 S22

Slide 1715th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

L-2L de-embedding based on

3-parameter PAD model is proposed.

According to the characteristic impedance of TL, the TL is de-embedded correctly.

Simulation and measurement results are matched well.

→An accurate model in mm-W is realized.

Conclusion

Slide 1815th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, 2015 San Diego, CA

Thank you for your attention!