A High-sensitivity 135 GHz Millimeter-wave Imager by Compact Split-ring-resonator in 65-nm CMOS Nan Li 1 , Hao Yu 1* , Chang Yang 1, Yang Shang 1 1 School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 1
Transcript
A High-sensitivity 135 GHz Millimeter-wave Imager by Compact Split-ring-resonator in
65-nm CMOS
Nan Li1, Hao Yu1*, Chang Yang1, Yang Shang1 1School of Electrical and Electronic Engineering,
Nanyang Technological University, Singapore
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Outline
1. Background and Motivation
2. 135GHz Millimeter-wave Imager by DTL-SRR
3. Imager Measurement and Imaging
4. Conclusion and Acknowledgement
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Presenter
Presentation Notes
Let us start with the Background and
Terahertz Radiation and Imaging Applications
General Specifications for medical imaging 1. Resolution • Penetration depth: 3~5 mm (Sensitive to thin
tissue) • Spatial resolution: ~ 200 μm • Depth resolution in the skin: ~ 40 μm (3D
Imaging) 2. Species-specific spectral absorption of THz energy • Sensitive to H-bond vibration 3. Non-ionizing → not harmful to body
[“Terahertz imaging comes into view”, Physics world, 2001] [“A promising diagnostic method: Terahertz pulsed imaging and spectroscopy”, World J Radiol 2011 March 28; 3(3): 55-65]
(0.1~10THz)
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Presenter
Presentation Notes
Terahertz radiation fills the gap between Electronics and Photonics Generally, its frequency range is from 0.1 to 10THz. THz radiation is showing great advantage in the application of imaging system. For instance, THz radiation is very sensitive to the thin tissue. it has better spatial resolution than the conversional imaging methods like MRI and X-ray And potentially, it can be used for 3D imaging with depth resolution of 40um. THz can help identify some chemicals or tissue with unique THz energy absorption property. More importantly, Thz radiation is non-ionizing, which is not harmful to the human body.
Comparison with Other Technologies Ultrasound X-rays
(radiology) MRI THz
Wave type longitudinal mechanical waves
EM waves (Ionizing radiation)
Strong Magnetic Field
(Non-ionizing radiation)
EM waves (Non-ionizing
radiation)
Frequency 106~108 Hz
1016 Hz to 1019 Hz 107~108 Hz 1011~1013 Hz
Transmission requirements
elastic medium No medium No medium No medium
Molecular interactions
no no no yes
Image resolution 0.5~1mm @ 7.5MHz 15nm 1mm 200um
Sensitivity in thin tissue
Low Low Low High
Penetration depth High (200~300mm)
High (Through whole
body)
High (Through whole
body)
Relative Low (3~5 mm)
Cost Low Low High TBD 4
• Civilian Security – Airport /Cargo Screening – Mail and Package
Inspection • Defense Security
– Explosives detection – Biological agent based
weapon detection • System Requirement
– Portability and small size-“Wand-like Detector”
– Long standoff distance – High resolution
Terahertz Imaging Applications
Tera View
physicsworld.com
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Presenter
Presentation Notes
THz radiation and imaging also has great potential in the security application It can be applied in Civilian security for the Airport /Cargo Screening and Mail and Package Inspection It also can be applied in the explosive and biological agent based weapon detection in the battle field. Such kind of applications requires the imaging system to have high portability, high resolution and long stand-off distance. However, prevailing laser based THz imaging systems suffers from the bulky problem and high cost.
Terahertz (THz) waves (frequency: 0.1 to 10 THz; 3 to 300 cm–1; wavelength: 30 μm to 3 mm), which exist between radio waves (electronics) and light waves (optics), are perfectly non-invasive, and can penetrate opaque materials Thanks to the advanced scaling of CMOS technology, the speed of CMOS transistors grows rapidly. As we can see from…. By year 2020, ft, fmax III-V compound THz waves pass through non-conducting materials such as clothes, paper, wood and brick. THz waves also occupy a unique window of the electromagnetic spectrum where a large number of molecules emit and absorb radiation. The signals produced when a molecule jumps among rotational modes form a unique and highly distinctive chemical fingerprint. More specifically, if we can explore compact, easy-to-manufacture THz spectrometers that can detect these fingerprints, we will be able to use them to identify the constituents in a patient's breath or detect a potentially dangerous substance. THz imaging systems, therefore, will be key enabling components in applications such as security surveillance, non-destructive testing, biology, radio astronomy, and medical imaging. On the sensing and communications, the absence of licensed frequency spectrum in the THz frequency range makes it possible to explore new unprecedented ideas on super-precise sensing at micrometer-level and multi-10-gigabit instant wireless access at the centimeter-level spacing between transmitter and receiver.
Why Not CMOS THz?
• Loss is high; output power is low; sensitivity is low; gain is low
• Single CMOS transistor has no advantage
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Presenter
Presentation Notes
One major concern on the THz imaging system is the path loss. As we can see from the path loss plotted in 1Km distance with 40dBi antenna gain, huge path loss is introduced in the THz frequency range. For instance, 1m path loss at 300GHz could be as high as 90dB. To overcome this huge loss in imaging system, We need high gain CMOS transistors and high-Q factor in passive structures. These parameters are not only limited by the active devices, but also the Q factor in passive In my work, I keen to improve the performance of THz imaging system with the application of metamaterial based approaches(THz phased array).
CMOS THz Electronics: In-Phase Addition
δΦ= 0 δΦ= 0
δΦ= 0
δΦ= 0 δΦ= 0
High added efficiency, high output power, high sensitivity
And metamaterial base passive structures in each pixel can realize high sensitivity
permeability
permittivity
RH T-line
LH T-line
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Group Velocity Propagation Velocity
Group Velocity Propagation Velocity
Metamaterial, the Transformer
Presenter
Presentation Notes
The relevance of meta-material here can be clarified by the figure below. For normal T-line, it has positive u and e; For a left-hand T-line, it has negative u and e. If we build CRLH T-line, we can build a zero-phase T-line to support interconnection at THz. When coupling either SRR or CSRR as load to a host T-line. A sharp stop-band is formed in such a medium at the resonant frequency such that the EM-wave can be perfectly reflected back into the host T-line to form a stable standing-wave with high Q. Metamaterial is not a traditionally defined material. By giving different structure and property to these unit cells, the whole array would show some property that does not exist in nature. A more clear definition could be given in this fig. The x axis is permittivity and the y axis is permeability. Most natural materials lies on the horizontal line where relative permittivity >=1 and relative permeability roughly =1. But with metamaterial, by giving different design for unit cells, theoretically we can construct a material located in any region on this fig.. This gives many interesting applications. When metamaterial appears in the 3rd quadrant, where both permittivity and permeability are negative. It is called left-handed material, one property of the left-handed material is that it’s phase velocity is negative. In other words, although the energy propagates forward in this material, the phase actually propagates backward. One application of left-handed material to composite with right-handed material to provide zero phase delay. When metamaterial appears in the 4th quadrant, where permittivity is positive and permeability is negative. It is called magnetic plasma, where evanescent wave formed. So the EM wave entering this region will be strongly reflected. One typical structure showing this property is SRR On the other hand, evanescent wave will also be formed by electric plasma, which appears in the 2nd quadrant with positive permittivity and negative permeability.
Metamaterial for In-Phase Signal Detection
• Resonant super-
regenerative detection
• Metamaterial based resonator to be deployed – High Q factor – Narrower
Bandwidth – Higher Sensitivity
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Presenter
Presentation Notes
In single pixal
Fundamentals of Super-regenerative Receiver
• Rayleigh-Hean thermal noise model:
S is the sensitivity, K is the Boltzmann constant, T is the ambient temperature, B is the bandwidth and NF is the noise figure.
• High-Q oscillator with narrow detection band for high sensitivity
VOUT
PinP1 P2
Positive FeedbackLNA
-Gm
Quench Signal
RMS Detector
Pin
VOUT
Quench Controlled Oscillator
High Q ResonatorLow Q Resonator
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Presenter
Presentation Notes
The core of super-regenerative receiver is a ocillator with quench controlled gain block and positive feedback Where the quench control signal is set, If there is no external signal injection, the oscillation amplitude builds up from thermal noise And it takes the longest time reach the maximum oscillation amplitude. If an external signal higher than the thermal noise level is injected, the oscillation amplitude builds up from the level of external signal, It takes shorter time to reach the maximum oscillation amplitude. As such, the averaged output power increases with the external injected power. The sensitivity of super-regenerative receiver equals the minimum power it can be detected, it is given in this equation. Where F is the NF, Pe is the bit error rate and omega s is the bandwidth. Since the bandwidth is mainly determined by the Q factor of resonator, The sensitivity is receiver can be improved by high Q resonator.
[9]
Antenna-less CMOS Imager at 245 GHz
Previous Work
• LC-Tank resonator is commonly used in current designs – Low Q factor – Wider Bandwidth – Lower Sensitivity
• Metamaterial Based Resonator to be deployed – High Q factor – Narrower Bandwidth – Higher Sensitivity
[2]
[1]
Multi-stage Super-regenerative Receiver at 144GHz
Time encoded Super-regenerative Receiver at 183GHz
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Presenter
Presentation Notes
Previous work based on CMOS super-RR are developed all based on the LC-Tank resonator with low Q–factor Thus the receiver has wider bandwidth and lower sensitivity In our work, High Q CSRR and SRR resonator is deployed to reduce the bandwidth of receiver and further improved the sensitivity
Metamaterial: Transmission Line loaded Complimentary Split Ring
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Presenter
Presentation Notes
EM-wave can be perfectly reflected back into the host T-line to form a stable standing-wave When coupling either SRR or CSRR as load to a host T-line, a plasmonic medium with single negative ε or μ could be formed, called electric or magnetic plasmonic medium.
Comparison between DTL-SRR and LC-Tank
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Presenter
Presentation Notes
Multi-stack structure is deployed here with larger mutual capacitance and larger mutual inductance, which can store more EM energy with less EM-energy leakage. This makes the DTL-SRR achieve higher area efficiency as well.
135GHz Super-Regenerative Receiver with TL-SRR based Oscillation Amplification
SRR Resonator
Quenched Negative Resistance
Low Pass Filter
Envelop Detector
LNA stage with transformer based matching network
RF Pads for on-wafer testing and wire-bonding to antenna
Capacitive Coupling
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Presenter
Presentation Notes
Another Super-Regenerative Receiver with SRR based Oscillator is designed at 145GHz Different from the previous design at 96GHz, transformer based input matching network is used. This is designed for the purpose of antenna integration with wire bonding The size of SRR resonator is only 35umx 35um, and whole receiver is implemented in GF 65nm CMOS process with the chip size of 460x570um
Measurement Setup
35um
GF 65nm CMOS
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Signal Generator
ChunkCarrier Board
Chip Under Test
Power and Control Interface
Vout
Quench-control
Cascade Microtech GSG Probe
Test Board
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Presenter
Presentation Notes
This is designed for the purpose of antenna integration with wire bonding area: 0.00845mm2 The size of SRR resonator is only 35umx 35um, and whole receiver is implemented in GF 65nm CMOS process with the chip size of 460x570um
Core Area (mm2) 0.021 0.013 0.75 0.0085 [1] A. Tang, et al., "A 144GHz 2.5mW Multi-Stage Regenerative Receiver for mm-Wave Imaging in 65nm CMOS," IEEE RFIC Symp., pp. 1-4, June 2011. [2] A. Tang and M. C. F. Chang, "183GHz 13.5mW/Pixel CMOS Regenerative Receiver for mm-Wave Imaging Applications", ISSCC Dig. Tech. Papers, pp. 296-298, Feb. 2011. [3] F. Caster, et al., “A 93-to-113GHz BiCMOS 9-Element Imaging Array Receiver Utilizing Spatial-Overlapping Pixels with Wideband Phase and Amplitude Control”, ISSCC Dig. Tech. Papers, pp. 144-145, Feb. 2013.
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Presentation Notes
The metamaterial and CON based receivers are compared to the state of the art recent published CMOS Super-regenerative Receiver in THz. We can see that the sensitivity of SRR and CSRR based receiver is higher than the previous work, and CSRR with CON can even have almost 9dB better sensitivity. Moreover, the NEP of our propose receiver are all much smaller than previous designs. However, temporarily this is only the simulation results, I will do the measurement as soon as the chip is returned. With TL-SRR reasonator
Transmission Imaging System at 135GHz
Y-A
xis
Mov
ing
135 GHz Antenna Array
on PCB
20 cm 20 cm
D-band Horn Antenna
Object Under Test
VDI-AMC-S176Frequency Quadrupler
R&S SMF100A Microwave Signal
GeneratorStage moving
controllerPC with testing
program
Proposed Regenerative
Receiver By SRR
Voltage Meter
USB Interface
Serial Interface
X/Y Moving Stage
2x4 Antenna Array
CMOS mm-Wave Imager
DTL-SRR-based SRX
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Mm-Wave Image Results Detected at 135 GHz Dry Moisturized
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Skin Samples
Moisturized Normal Pill Samples
Bag with knife, perfume and Coin
Knife Handle Perfume bottle
Knife 20 cents Coin
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Conclusion
• A high sensitivity 135GHz millimeter-wave (mm-wave) imager has been demonstrated on-chip in 65nm CMOS by differential transmission-line loaded with split-ring-resonator (DTL-SRR),
• Compared to the conventional super-regenerative mm-wave imager with LC-tank resonator at the similar frequency, the proposed metamaterial mm-wave imager has 2.8-4.3dB improved sensitivity and 60% reduced area.
• The integrated mm-Wave CMOS imager has various demonstrated diagnosis applications with great potential for the design of the future large arrayed transmission-type mm-wave imaging system.
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Acknowledgements
• This work is funded by MOE Tier-1 RG 26/10 and NRF2010NRF-POC001-001 grants.
