Rapid and Energy-Efficient Molecular Sensing Using Dual mm

17.6: Rapid and Energy-Efficient Molecular Sensing Using Dual mm-Wave Combs in 65nm CMOS: A 220-to-

320GHz Spectrometer with 5.2mW Radiated Power and 14.6-to-19.5dB Noise Figure© 2017 IEEE International Solid-State Circuits Conference 1 of 38

Rapid and Energy-Efficient Molecular Sensing

Using Dual mm-Wave Combs in 65nm CMOS:

Cheng Wang and Ruonan Han

Massachusetts Institute of Technology

Cambridge, MA, USA

A 220-to-320GHz Spectrometer with 5.2mW Radiated Power and 14.6-to-19.5dB Noise Figure



Outline

• Background

• Dual-Frequency-Comb Spectroscopy

• Architecture and Circuit Design

• Measurement Results

• Conclusions



mm-Wave/THz Rotational Spectroscopy

• Rotation of polar molecules leads to absorption spectrum‒ Maximum absorption in mmW/lower-THz range

‒ Sub-MHz Doppler-limited linewidth high selectivity

Gas SampleTx Rx

IF signal

detection

IF

Rotational spectrum

0 0.3 0.6 0.9 1.2

40

60

80

100

Tra

ns

mit

tan

ce

(%

)

16O

12C

32S

Frequency (THz)

J=1

J=40

Detection of rotational

spectral lines using EM wave

Peak absorption intensity at

mmW/sub-THz band

J - quantum number



Portable Molecular Sensor: Applications

[tabletopwhale.com]

• Human breath analyzer for

biomedical diagnosis

• Environment monitoring

for toxic gas leakage‒ Sensor network

‒ UAV platform

[www.dji.com]75% N2

13% O2

6% H2O 5% CO2

1% volatile organic compounds

3500 chemical species

Concentration: ppm-to-ppt level

Bio-makers for diseases or

metabolic disorders

(e.g. acetone glucose

Type 1 diabetes)

1% VOC

Hu

ma

n e

xh

ale

d g

ases



Challenges of Chip-Scale Spectrometer

MoleculeFrequency

(GHz)Toxic?

Flammable

?

Carbon Monoxide (CO) 230.538001 Y Y

Sulfur Dioxide (SO2) 251.199668

Hydrogen Cyanide (HCN) 265.886441 Y

Hydrogen Sulfide (H2S) 300.511959 Y

Nitric Oxide (NO) 250.436966 Y

Nitrogen Dioxide (NO2) 292.987169 Y

Nitric Acid (HNO3) 256.657731 Y

Ammonia (NH3) 208.145904 Y

Carbonyl Sulfide (OCS) 231.060989 Y Y

Ethylene Oxide (C2H4O) 263.292515 Y

Acrolein (C3H4O) 267.279359 Y

Methyl Mercaptan

(CH3SH)227.564672 Y

Methyl Isocyanate

(CH3NCO)269.788609 Y

Methyl Chloride (CH3Cl) 239.187523 Y Y

Methanol (CH3OH) 250.507156 Y Y

Acetone (CH3COCH3) 259.6184 Y Y

Acrylonitrile (C2H3CN) 265.935603 Y Y

[Source: HITRAN.org]

• High selectivity– Wideband(100GHz), high resolution(10kHz) spectrometer

• High sensitivity, fast scanning– High radiated power (below saturation), low noise detection

• High energy efficiency

[C. F. Neese, IEEE Sensors Journal, 2012]

periodic

Spectrum: 210-270GHz



Outline

• Background




• Conclusions



Dual-Frequency-Comb Spectroscopy

Conventional single-tone spectroscopy

Dual-frequency-comb spectroscopy

• Simultaneous scanning using 20 comb lines

(8 minutes for 100GHz bandwidth, τint=1ms)

• Single frequency sweep (e.g. ~3 hours for 100GHz bandwidth, τint=1ms)

IF

f0 Gas Sample

320f (GHz)220 320f (GHz)220

f0 f0-IF

f0 TX RX

fref - fIF/6

IF1,2, ,n

fD: 10GHz

fref

Gas Sample

IF1,2, ,n

Comb A Comb BfD

Spectrum of Comb A Spectrum of Comb B

320f (GHz)220

fD

320f (GHz)220

fIF

TX+RX TX+RX



Energy Efficiency Improvement

• Dual frequency combs (DFC) scheme breaks the conventional

efficiency-bandwidth tradeoff using parallelism

• Linear scalability between bandwidth and energy consumption

Radiated power of silicon-

based sources above 200GHz

Total energy consumption for

full-band scanning

This work

TST

2016

On-wafer measured with an

assumed 50% radiation efficiency Radiated

RFIC

2016

RFIC

2015

ISSCC

2015

ISSCC

20161

PBW

JSSC

2013

TST

2015MTT

2012

CSICS

2012 ISSCC

2016

ISSCC

2015

3 4 8 16 24 40

Bandwidth (%)

102

104

106

Co

ns

um

ed

en

erg

y (a

.u.)

DFC spectrometer

Conventional

single-tone

spectrometer

100×

10×

3E BW

2E BW

E BW



Outline

• Background




• Conclusions



Architecture of A 220-to-320GHz Comb

• Tunable transceiver: 10 active molecular probes (AMP)‒ Seamless coverage of 100GHz bandwidth

‒ Simultaneous transmit and receive ~2x higher efficiency

fref : 45~46.67GHz fD/2: 5GHz

Tripler

BufferDown-Mixer

Up-Mixer

IF-1 IF-2 IF-3 IF-4 IF-5

IF0 IF1 IF2 IF3 IF4

2f0

f0=3fref Up-Conv.

Chain

Down-Conv.

Chain

2f0+fD 2f0+2fD 2f0+3fD 2f0+4fD

2f0-fD

2f0-2fD 2f0-3fD 2f0-4fD 2f0-5fD

Active Molecular

Probe (AMP)



Distributed Comb-Spectral Radiation

Hemispheric

silicon lens

CMOS chip

• On-chip backside radiation through 10 radiators‒ Improved antenna efficiency by narrowband operation

• High-resistivity hemispheric silicon lens is used‒ Lower sensitivity to the radiator offset from the center

(compared to hyper-hemispheric lens)

‒ No additional beam collimation



Active Molecular Probe (AMP)

• Multi-functional module simultaneously performs ‒ Highly-efficient frequency doubling

‒ Low-noise heterodyne sub-harmonic down mixing

‒ Efficient antenna for input/output radiation waves

Input +

@ f0

VG

VD & Mixer Output @ fIF

Input -

@ f0

fIF

f0

TX: 2f0

RX: 2f0+fIF

X2

+

-

Balun

Buffer

Core of AMP

Core

Slot balun

Output -Input

Output +

f 0



AMP TX Mode: Frequency Doubling

f 0

Input +

@ f0

VG

RF

Choke

@ 2f0

VD & Mixer Output @ fIF

Input -

@ f0

TX: 2f0

RX: 2f0+fIF

• Conditions for high conversion efficiency‒ Maximum device power gain at fundamental frequency (f0)

‒ Minimum loss at 2f0 (e.g. harmonic feedback to the lossy gates)

‒ Instantaneous signal radiation at 2f0



Maximum Device Power Gain Gmax

• Upper limit of matched power gain Gmax depends on

the unilateral gain U

Gms/GmaUnilateral gain U

Gmax, ~4U

fmax

U = 4

Gmax = 3.5U

Simulation using 65nm bulk

CMOS process

[R. Spence, Linear Active Networks 1968]

[O. Momeni, ISSCC 2013]



Conventional YZ Embedding for Gmax

[R. Spence, Linear Active Networks 1968]

• Issues of YZ embedding with lumped elements‒ Loss from DC feed to bypass source current

‒ Loss from parasitic resistor associated with the source

‒ Impractical large inductor for Y element due to distributed

effect in high frequency

Y element for

shunt feedback

Z element for

series feedback

IN

OUT

DC

feed

Rsb

Csb

N+ N+

P type substrate

GateSource DrainBulk

Z element

Rsb

Y elementDC

feed

IN OUT

Csb

P+

Equivalent circuit Transistor structure



Dual-transmission-line (DTL) Feedback

Gmax, K=1

Original power gain

5 dB gain

boost

fmax

where

• Adopt distributed feedback elements

• Ground the source of transistor

• Achieve Gmax accurately

Equations for feedback

parameter calculation:

Simulation using 65nm CMOS processTL1 (Z1,θ1)

Slot2 (Z2,θ2)

IN

OUT



DTL Feedback Based on Slot Line @f0

Quasi-TEM Wave (Differential Mode)

Supported

E-field distribution @ f0

K=0.9, w/o

feedback

K 1, with DTL

feedbck

K

TM Wave(Common Mode)

Rejected

Simulated stability factor, K

Feedback through Slot 2

Electrical field Current



Loss Minimization and Radiation @2f0

Quasi-TEM Wave (Differential Mode)

Supported

TM Wave(Common Mode)

Rejected

E-field distribution @ 2f0Folded-slot antenna

Harmonic signal isolation




Simulation Results for Doubler at 275GHz

• 65nm bulk CMOS

• NMOS W/L=24μm/60nm

• Output power: 1.6mW

• Doubler efficiency: 43%

• Antenna efficiency: 45%

Doubler efficiency η (%) Antenna directivity

η=18%, w/o

feedback

η=43%, with DTL

feedback

η (%)



AMP RX Mode: Heterodyne Mixing

• Mixer LO signal is the same as the doubler input signal @f0

• Further noise reduction: zero drain bias current

varistor mode mixing with reduced channel noise

Simulated SSB noise figure




Slot Balun with Orthogonal Mode Filtering

• Amplitude and phase imbalance

in conventional baluns causes‒ Lower doubler efficiency

‒ Higher LO signal radiation at f0

• Proposed slot balun‒ Orthogonal mode filtering

‒ Symmetric output coupling

Active Molecular Probe (AMP)

Slot: λ/4 Resonator

Output -Input

Output +

Differential mode

(support)

Common mode

(reject)

In

Out

In

fIF

f0

RX: 2f0+fIF

X2

+

-

Balun

Buffer Core

Electrical field

Open Open



Slot Balun with Orthogonal Mode Filtering

Simulated S-parameterSimulated amp. and phase error

• Nearly perfect single-ended signal to differential

signal conversion without errors

• Minimum insertion loss: 0.9 dB

• -10dB return loss bandwidth: 30%



Up/Down-Conversion Mixer

• SSB mixers configured for up/down conversion chains

fref :

45~46.67GHz

f0

Up-conversion

Chain

Down-conversion

Chain

fD/2: 5GHz

f0+5GHz f0+10GHz f0+15GHz f0+20GHz

f0-5GHz f0-10GHz f0-15GHz f0-20GHz f0-25GHz

VGG VGG

Lange Coupler

f0 , 180

f0 , 0

f0 , 270

f0 , 90

VB

RF: f0+5GHz

VDD

VA

VC

VD

Static Frequency

Divider

LO: f0

fD: 10GHz

VA VB VC VD

5GHz IF IQ signals

0

90

270

180

fD: 10GHz

fD/2: 5GHz

DQ

Q CLK

DQ

QCLK



Up/Down-Conversion Mixer

• IF phase configuration up or down sideband selection

• Low conversion loss: 2.3 dB

• Rejection of image, LO and inter-modulation signals: >30dB

f0

31dB

30.8dBf0

Phase(VA,VB,VC,VD)=(0°,180°,90°,270°)

Down sideband conv.

Phase(VA,VB,VC,VD)=(0°,180°,270°,90°)

Up sideband conv.



Outline

• Background




• Conclusions



Chip Micrograph and Packaging

Chip on PCB with Silicon Lens

• TSMC 65nm bulk CMOS process

• Chip area: 2mm×3mm

• DC power consumption: 1.7W

Chip bonded on PCB

with hemispheric

silicon lens

3 mm

2 m

m



Measurement Setup of TX Mode

Signal Source (13.7-20GHz)

Spectrum Analyzer

VDI WR-3.4 EHM

Diplexer

WR-3.4 Horn Antenna

Spectrum/Antenna Pattern Measurement

φ

θ

Sensor HeadmW

WR-3.4-10 Taper

Erikson PM4 Power Meter

Power Measurement

WR-10 Waveguide

PCB

IF

LO

LNA

Loss0.7dB

Distance, d = 10cm

fref

IF=280MHz

Signal Source (fDigital=10GHz)

Signal Source (fref=45-46.67GHz)

fdigital

• For power measurement, only one AMP is turned on

at each time

Power measurement

using VDI Erickson

PM-4 power meter



Measurement Results of TX Mode

Antenna pattern of a comb

line at 265GHz

Equivalent isotropic

radiated power (EIRP)

• Total radiated power of 10 comb lines: 5.2mW



Measurement Results of TX Mode

Phase noise of 10 comb

lines

• Average measured phase noise for 10 comb lines at

1MHz offset: -102dBc/Hz

Span=10kHz

RBW=10Hz

Spectrum of a comb line

at 265GHz



Measurement Setup of RX Mode

Signal Source

Horn Antenna

φ

θ

PCB

Distance = 15 cm

Signal Source

(fDigital=10GHz)

Signal Source

(fref=45-46.67GHz)

Spectrum

Analyzer

LNA IF=280MHz

IFiFrequency

Extender

Output: 220-320GHz

NF = IF noise floor (dBm/Hz) – (-174 (dBm/Hz)) – CG (dB)

Single-sideband noise figure (antenna loss incorporated)

Single-sideband conversion gain

CG =IF output power

Power received by RX antenna aperture

= IF output power (dBm) – (TX power (dBm) +TX antenna gain (dB)

– Path loss (dB) + RX antenna directivity (dB))



Measurement Results of RX Mode

• Measured SSB noise figure: 14.6~19.5dB

Single-sideband conversion gainSingle-sideband noise figure



1. 1 MHz frequency offset.

2. The Pradiated is estimated from the PA output power of 2.9 mW, and the antenna loss of 6 dB.

3. The NF of low noise amplifier in the receiver, excluding on-chip antenna loss.

4. The reported power in [3] is EIRP, not the total radiated power.

5. The overall NF (18.4~23.5 dB) =NFISO(13.9~19 dB, Isotropic Noise Figure)- (Antenna Loss (~4 dB) + Antenna

Gain (-1~2 dBi)) .

Ref.Frequency

(GHz)BW

(GHz)Pradiated

(mW)Phase Noise1

(dBc/Hz)Noise Figure

(dB)

This work

Topology

Comb(Tx/Rx)

220~320 100 5.2 -102 14.6~19.5

Tx+Rx 245 14 4.0 -85 18

Rx 210~305 95 N/A N/A18.4~23.55

(NFISO=13.9~19)

Tx 317 N/A 3.3 -79 N/A

208~255 47Tx 0.14 -80 N/A

210 14 0.72 -81 11~123Tx+Rx

PDC (W)

1.7

1.5+0.6(Tx+Rx)

0.24+0.086(Tx+Rx)

1.4

N/A

0.61

Technology(fmax)

65nm CMOS(250GHz)

0.13μm SiGe(500GHz)

65nm CMOS(N/A)

0.13μm SiGe(280GHz)

32nm CMOS(320GHz)

65nm CMOS(N/A)

TST2016

ISSCC2016

JSSC2015

VLSI2016

JSSC2014

Performance Comparison Table



Spectroscopy Demonstration Setup

Spectroscopy setup at

MIT Terahertz Integrated

Electronics Lab

• Wavelength modulation (WM) is applied for reduced

impacts due to standing-wave formation‒ ∆f=240kHz, fm=50kHz, fIF=950MHz

Comb A Comb BGas Chamber

fIF

fm 2fm

LNABPFDetector

IFi

L=70 cm, Pressure =3 Pa

WM input

fref+Δf/6·sin(2πfmt)

Signal SourceSignal Source

Lock-in amplifier

fref – fIF/6

GPIB

GPIB

fm

Laptop

fm

Output

Spectral

line

Freq

Am

pli

tud

e

Time

Time



Spectrum of Acetonitrile (CH3CN)

Spectral line w/o WM

Spectral line with WM

Measured spectrum of CH3CN

• Measurement matches the JPL

molecular database

• Spectral linewidth of 380kHz is

obtained‒ Absolute specificity (Q=7×105)

[JPL Molecular Spectroscopy, spec.jpl.nasa.gov.]



Spectrometer Miniaturization

1st order derivative, SNR=54dB

2nd order derivative, SNR=44dB

3cm-long gas cell

• 54dB SNR has been achieved

with reduced gas cell size‒ Compact 3cm-long gas cell

‒ Sample: carbonyl sulfide (OCS),

1.21×10-21 cm integrated line

intensity (JPL) at 279.685GHz

‒ Integration time: 100ms

Comb A

Comb B



Outline

• Background




• Conclusions



Conclusions

• Architecture level: Dual-frequency-comb spectroscopy with

>2N× (N=10) faster frequency scanning and lower total

energy consumption

− Simultaneous bilateral transmit/receive

• Circuit level: multi-functional active molecule probe (AMP),

performing frequency doubler, sub-harmonic mixer and on-

chip antenna simultaneously

− Proposed dual-transmission-line (DTL) feedback accurately

achieves Gmax

• Prototype: 220-to-320GHz comb spectrometer with state-of-

the-art 5.2mW radiated power and 14.6-to-19.5dB NF

− Spectroscopy demonstration with 3-cm gas cell and a SNR

of 54dB



Acknowledgement

• MIT Center for Integrated Circuits & Systems

• TSMC University Shuttle Program

• Dr. Richard Temkin (MIT Physics), Prof. Tomás Palacios (MIT

EECS), Prof. Ehsan Afshari (University of Michigan) and Prof.

Anantha Chandrakasan (MIT EECS) for the support of testing

instruments

• Dr. Stephen Coy, Prof. Keith Nelson, Prof. Robert Field (MIT

Chemistry), Tingting Shi (MIT and Fudan University) and Prof.

John S. Muenter (University of Rochester) for technical

discussions and assistance

Documents

Rapid and Energy-Efficient Molecular Sensing Using Dual mm