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Millimeter-Wave and Terahertz Antennas: from PCB to Silicon

Sanming Hu, Hongfu Meng, Wenbin Dou

State Key Laboratory of Millimeter Waves, Southeast University, Nanjing, China

17th Oct., APCAP2017, Xi’an, China

毫米波国家重点实验室State Key Lab. of Millimeter Waves

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Copyright

©The use of this work is restricted solely for academicpurposes. The author of this work owns the copyright and noreproduction in any form is permitted without writtenpermission by the author.

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Abstract

Millimeter-wave (mmWave) and terahertz (THz) technologies enable a largenumber of exciting applications, such as space exploration, high-speedcommunication, self-driving, non-ionizing imaging. In these and other mmWaveand THz systems, antennas play key roles since they significantly affect and evendirectly determine the system performance and cost.

This talk presents five different antennas from PCB to Silicon, i.e., (1) 94GHzreflectarray in printed circuit board (PCB), (2) 135GHz silicon antenna fabricated byin-house BCB-Silicon process for mmWave 3DIC, (3) a horn antenna compatiblewith through-silicon via process for our proposed mmWave 3D SiP, (4) a substrate-integrated waveguide antenna in commercial SiGe BiCMOS process, it achieve fullintegration and frequency reconfigurablity from 397 to 428GHz, and (5) a 315GHzantenna to be inherently integrated with graphene detector in the same high-resistivity silicon substrate.

The above research partially reviews our effort in mmWave and THz antennas, andprovides a reference for mmWave/THz antennas and systems.

Keywords: Silicon antennas, PCB antenna, on-chip antennas, through-silicon via

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Sanming Hu received his Ph.D. degree in 2009 from SoutheastUniversity (SEU), Nanjing, China, where he is a Professor.

From 2006 to 2009, he visited Nanyang TechnologicalUniversity, Singapore, for his doctoral research. From 2009 to2015, he was a Senior Research Engineer, a Scientist I, and aScientist II at the Institute of Microelectronics, A*STAR,Singapore, an Alexander von Humboldt Research Fellow atUniversity of Ulm, Germany, and then an Assistant Professor atHeriot-Watt University, Edinburgh, UK.

Dr. Hu is a Senior Member of IEEE and CIE. He served as a GuestEditor of SCI Journals. As the first author, he received the BestPaper Award of the IEEE Transaction on Components,Packaging, and Manufacturing Technology (2012). He was arecipient of the Recruitment Program of Global Experts – YoungProfessionals, China (2015).

Biography of 1st Author

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Outline

Millimeter Waves and Terahertz

mmWave/THz Antennas

① 94GHz Reflectarray Antennas

② 135GHz Antenna for 3D IC

③ 135GHz Horn for 3D SiP

④ 315GHz Dipole for Graphene Detector

⑤ 400GHz SIW Antenna for SoC

Summary

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Millimeter Waves and Terahertz

Millimeter-Wave (mmWave or MMW)A wavelength-based term Wavelength = 1 ~ 10mm Frequency = 30 ~ 300GHz

Terahertz (THz, sub-mmWave, far-infrared) A frequency-based term

What is the Freq. Range of THz?Photonics: 0.1THz (100GHz) – 10THzElectronics: 0.3THz (300GHz) – 3THzCommon: 0.3THz (300GHz) – 10THz

… Supper High Frequency Millimeter-Wave Terahertz (THz) Infrared Visible Light …

Electronics Photonics

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Google’s 60GHz Project Soli

mmWave and THz Applications

5G Communication

Automotive Radar

Space Application

And More……

© P. D. Maagt, etc

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94GHz Reflectarray Antenna

Outer Loop

Inner CircleR0

R1

R2

Ground

ReflectElement

Substrate

Element Sizes: 1.5mm×1.5mm

Phase Shift: -1600~+2000

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94GHz Reflectarray Antenna

Reflect Aperture Sizes: 75mm×75mm

Offset Angle: 26.5°Main Beam Direction: θ0 = 0°

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94GHz Monopulse Reflectarray

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94GHz Monopulse Reflectarray

E-Plane H-Plane

Diffe

rent

ial

Sum

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mmWave 3D Integrated Circuits

Source: S. Hu etc, IEEE Trans. CPMT

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135GHz Antenna for 3D IC

SourceS. Hu etc, IEEE Trans. CPMT (Best Paper Award))

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S Parameters and Gain

10-dB RL bandwidth: 116 - 141 GHz (sim.); ~110 – 147 GHz (meas.) Wide impedance bandwidth is achieved using two resonances BCB filling significantly benefit the silicon process, reduce the

cavitity size by 76.8%, and remain the antenna gain

120 125 130 135 140 1450

1

2

3

4

5

6

7

8

Gain

(dBi

)

Frequency (GHz)

BCB (tanδ =0) + polymer (tanδ =0) + PEC BCB (tanδ =0) + polymer (tanδ =0) + Cu BCB (tanδ =0.01) + polymer (tanδ =0) + Cu BCB (tanδ =0.01) + polymer (tanδ =0.01) + Cu

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Measurement

120 125 130 135 140 1450

1

2

3

4

5

6

7

8

Effic

ienc

y (%

)

Gai

n (d

Bi)

Frequency (GHz)

Measured Gain Simulated Gain

80

85

90

95

100

Simulated Efficiency

Simulated high efficiency around 86% Measured high gain (5.4 dBi @135 GHz)

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Printed Circuit Board

Organic Substrate

Organic Substrate

PCB

Organic Substrate

Wav

egui

deRa

diat

or

3D Explored View

Front-Side View

Horn antenna formed by normal solder balls

Horizontal radiation to benefit applications such as chip-to-chip communication

Horn antenna fed by a normal solder ball as a current probe

Antenna for mmWave 3D SiP

Source: S. Hu etc, EuCAP

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Radiation Pattern

It works as a typical SIW horn antenna

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Antenna Gain Improvement

Bigger ball, higher gain, available ball/ball height: 0.04~ 0.76 mm Proposed antenna has ~2.1dB higher gain than the best case of a horn filled

by FR4 (tanδ=0.018 at 10 GHz). Proposed antenna has ~14dB higher gain than the best case of a horn filled by

Silicon (ρ=100 Ω∙cm)

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THz Graphene Detector

L. Vicarelli, etc. Nature Materials, Oct. 2012A. Zak, etc. Nano Letters, 5834-5838. 2014

Expected and Reported Antenna for THz Imager

Expected Reported

Impedance(ohms)

Several thousand (to perfectly match GFET. Exact value depends on GFET) 50 or 188

Gain (dBi) Higher is better -10 ~ 0

Bandwidth Narrow (to reduce input noise) Wide

A better antenna will significantly benefit a THz imager

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315GHz Proposed Antenna Structure

Silicon(k=11.9)

Air (k=1) Antenna

Reported antennas mainly use this top-side radiation,

it is very weak due to high k of Silicon

Flip the silicon chip on FR4 PCB, now we can

use the strong radition

Flip the chip

Printed Circuit Board (PCB)

Bended dipole is proposed to get

high impedance & differential feeding

GFET

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Antenna Layout0.6 mm

0.6

mm

S G

D

D

40 mm

PCB_Top PCB_Bottom

Detector Chip

AntennaGraphene

FET

Full MetalD

G S

D

Frequency: 315 GHz Impedance: 5000 ohms

Chip substrate: High-resistivity (10k) silicon Chip size: 600um x 600um x 525um PCB substrate: for supporting & biasing

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3D Radiation Pattern

High-resistivity (10k) Silicon works as a superstrate

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2D Radiation Pattern

High gain (9.47dBi vs -10~0 dBi for reported designs)

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Antenna Input Impedance

High impedance (5k ohms) to match GFET THz detector

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Reflection Coefficient

Narrow bandwidth (3.5 GHz) to reduce input noise

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400GHz Reconfigurable SIW Antenna

TM2

TM1

M5

Close-up of Q1 and Q2 connection3D view of SIW antennaMetal layers

M4

M3

M2M1

V_Q2(M1 layer)

V_Q1(M1

layer)

Vias from TM2 layer

to M1 layer

Sidewall (vias from TM2 layer

to M1 layer)

Sidewall (vias from TM2 layer to M3

layer)

Ground (M1 layer)

TM2 layer

Sidewall (vias from

M3 layer to M1 layer)

Radiation slot (TM2

layer)

Ridge (M3

layer)

Q2

Q1Radiation slot

(TM2 layer) Q1=0.12um x 0.84 umQ2=0.12um x 0.84 um

Two transistors (Q1 and Q2) are employed as switches to control the physical length of the slot and therefore the operation frequency

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Radiation Pattern

Simulated antenna gain: -0.55dBi vs -7dBi (patch, JSSC2010) Close structure: alleviate the undesired surface-wave and

electromagnetic interference to nearby active circuits

030

60

90

120

150180

210

240

270

300

330

-21-18-15-12-9-6-30

-21-18-15-12-9-6-30

Theta (degree)Ga

in (

dBi

)

126o

XoZ Plane YoZ Plane

- 0.55 dBi

88o

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S Parameters of SIW Antenna

360 370 380 390 400 410 420 430 440-25

-20

-15

-10

-5

0

|S

11| (d

B), G

ain (d

Bi)

Frequency (GHz)

Q1 OFF, Q2 OFF: |S11| Q1 OFF, Q2 OFF: Gain Q1 ON, Q2 OFF: |S11| Q1 ON, Q2 OFF: Gain Q1 OFF, Q2 ON: |S11| Q1 OFF, Q2 ON: Gain

Antenna gain: ~ -0.5dBi Impedance bandwidth:

397-408GHz, 406-418GHz, and 417-428GHz

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THz Silicon Chip with SIW Antenna

400GHz Transmitter & Receiver Chipset

Source: S. Hu etc, IEEE JSSC, pp.2654-2664

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Summary

mmWave/THzAntennas

for 3D IC

for SoCfor 2D

GrapheneDetector

for 3D SiP

Thanks for Your Attention

for System on PCB