Large-Scale Terahertz Active Arrays in Silicon Using Highly-Versatile Electromagnetic Structures

Transcription

1 Large-Scale Terahertz Active Arrays in Silicon Using Highly-Versatile Electromagnetic Structures (Invited Paper) Cheng Wang, Zhi Hu, Guo Zhang, Jack Holloway and Ruonan Han Dept. of Electrical Engineering and Computer Science Microsystem Technology Laboratories Massachusetts Institute of Technology

2 The Dawn of a New Terahertz Era Applications (Demos) Today Enabling Technology 2

3 The Dawn of a New Terahertz Era Applications (Demos) Today The Next THz Era Enabling Technology Cost & Size System Complexity 3

4 The Dawn of a New Terahertz Era Applications (Demos) Today The Next THz Era Enabling Technology Cost & Size System Complexity 4

5 Recent Progress and New Challenges P out (dbm) [IMS 2013] [ISSCC 2013] Our Work [ISSCC 2014] [ESSIRC 2013] [ISSCC 2012] Our Work [ISSCC 2015] [T-MTT 2014] [ISSCC 2014] f out (THz) DC to THz Radiation Efficiency (%) E E-4-4 [ISSCC 2008] [IMS 2013] [ESSIRC 2012] [ISSCC 2013] [ISSCC 2011] [ISSCC 2014] [ISSCC 2012] [VLSI 2011] [R. Han, etc., IEDM 2016] Our Work [ISSCC 2015] Our Work 1E Year 5

6 Recent Progress and New Challenges P out (dbm) [IMS 2013] [ISSCC 2013] Our Work [ISSCC 2014] [ESSIRC 2013] [ISSCC 2012] Our Work [ISSCC 2015] [T-MTT 2014] [ISSCC 2014] f out (THz) DC to THz Radiation Efficiency (%) E E-4-4 [ISSCC 2008] [IMS 2013] [ESSIRC 2012] [ISSCC 2013] [ISSCC 2011] [ISSCC 2014] [ISSCC 2012] [VLSI 2011] [R. Han, etc., IEDM 2016] Our Work [ISSCC 2015] Our Work 1E Year What are the true advantages of using silicon IC for THz hardware (besides low cost, baseband integration )? 6

7 Large-Scale Terahertz Active Array Integration Capability of Silicon Chips Homogeneous Array Power combining Beam collimation Beam steering Heterogeneous Array Broadband sensing Parallel signal processing Waveform generation 7

8 Outline Background Homogeneous Array: 1-THz Radiation Source Multi-Functional Mesh Structure Chip Prototype in SiGe and Measurement Results Heterogeneous Array: 220-to-320GHz Frequency-Comb Spectrometer High-Parallelism Architecture and THz Molecular Probing Module Chip Prototype in CMOS and Measurement Results Gas-Sensing Demonstration Conclusion 8

9 Outline Background Homogeneous Array: 1-THz Radiation Source Multi-Functional Mesh Structure Chip Prototype in SiGe and Measurement Results Heterogeneous Array: 220-to-320GHz Frequency-Comb Spectrometer High-Parallelism Architecture and THz Molecular Probing Module Chip Prototype in CMOS and Measurement Results Gas-Sensing Demonstration Conclusion 9

10 Normalized Power (db) Normalized Power (db) Normalized Power (db) Beam Collimation in a Radiator Array θ D=λ/4 D=λ/2 D=λ D Angle (degree) Angle (degree) Angle (degree) Array of N coherent radiation sources enables: Power combining from a large number of solid-state devices Beam collimation through wave interference The far-field radiation intensity increases by N 2 Optimum Element Pitch: λ/2 10

11 # of Coherent Radiators High-Density, Large-Scale Active Array on Chip Beam Width (degree) 2 mm 1 Antenna (JSSC 2002) 2.2 mm 4 Antennas (ISSCC 2013) Frequency (THz) Note: Calculations Based on a 10mm 2 Active Area Optical Antenna Array If the λ/2 pitch is achieved: >10/mm 2 radiators at 300 GHz can be built D opt is ~300μm (with ε r,eff 3) High effective isotropically radiated power (EIRP) may be maintained in the mid-thz range Long transmission distance 11

12 # of Coherent Radiators Power (dbm) PN (dbc/hz) VCOs+Buffers 1.3mm High-Density, Large-Scale Active Array on Chip 2.2 mm Our Work 1 mm Radiators 2 mm 1 Antenna (JSSC 2002) Beam Width (degree) 4 Antennas (ISSCC 2013) 16 Antennas (ISSCC 2015) Frequency (THz) Note: Calculations Based on a 10mm 2 Active Area Optical Antenna Array Other PLL Blocks 1.6mm Phase Noise After Locking 100KHz 10MHz K 100K 1M 10M 100M Frequency (Hz) -90 Frequency Locked Free Running Frequency (GHz) 320-GHz Array w/ PLL in SiGe BiCMOS 4x4 elements in 1-mm 2 area [R. Han, ISSCC 2015] 3.3mW total radiated power (EIRP: 24mW) 12

13 # of Coherent Radiators High-Density, Large-Scale Active Array on Chip Beam Width (degree) 2 mm 1 Antenna (JSSC 2002) 2.2 mm 4 Antennas (ISSCC 2013) Our Work 1 mm 16 Antennas (ISSCC 2015)?? Frequency (THz) Note: Calculations Based on a 10mm 2 Active Area Optical Antenna Array ~100/mm 2 radiator density should be possible Only 3 of beamwidth using 10-mm 2 chip area (~1000 coherent radiators) Large challenges Signal generation at 1 THz Available radiator area: μm 2 Highly scalable array architecture 13

14 Implementation Challenges 500 Cutoff Frequency of Silicon Devices High-Order Harmonic Radiation Measured fmax (GHz) (Interconnect Included) SiGe 100 CMOS Technology Node (nm) 1. Fundamental (f 0 ) Oscillator 2. Frequency Quadrupler λ f0 /4=λ 4f0 f 0 x 4 3. Antenna at 4f 0 λ 4f0 /2 4. Filters for Unwanted Harmonics f 0 2f 0 3f 0 4f 0 f 0 =250GHz, f out =4f 0 =1THz Available Area λ 4f0 /2 [R. Shmid, et al., IEEE Trans. Electron Devices 2015] Low device speed requires high-order harmonic generation Optimal device conditions at all harmonic frequencies should be met The available area is too small for all these necessary functions 14

15 Enabling Technology: Versatile EM Designs 1. Fundamental (f 0 ) Oscillator 3. Antenna at 4f 0 λ 4f0 /2 λ f0 /4=λ 4f0 Multi- Functional Structure 2. Frequency Quadrupler f 0 x 4 λ 4f0 /2 4. Filters for Unwanted Harmonics f 0 2f 0 3f 0 4f 0 A multi-functional electromagnetic structure around the transistors to simultaneously perform all the above tasks Orthogonality of various EM wave modes Multi-order standing-wave interference in the near field 15

16 # of Coherent Radiators High-Density, Large-Scale Active Array on Chip 2.2 mm 1 mm Our Work 1 mm 1 mm 2 mm 1 Antenna (JSSC 2002) 4 Antennas (ISSCC 2013) 16 Antennas (ISSCC 2015) 91 Antennas (RFIC 2017) Optical Antenna Array Beam Width (degree) Frequency (THz) Note: Calculations Based on a 10mm 2 Active Area 1-THz Array in 130-nm IHP SiGe BiCMOS 91 coherent radiator in 1-mm 2 area 0.1-mW total radiated power (EIRP: 20mW) [Z. Hu and R. Han, IEEE RFIC, Jun (Best Student Paper Award-2 nd Place)] 16

17 Fundamental Oscillation at f 0 =250GHz λ f0 /8 AC Short C Cap D C Q 250GHz λ f0 /8 B A B Cap D C B A B C f 0 λ f0 /4 At f 0, each square slot line behaves as a pair of λ/4 standing-wave resonators Optimal Fundamental Oscillation 17

18 Multi-Order Standing Wave Interference C Cap D C C Cap D C C Cap D C C Cap D C B A B B A B B A B B A B Cap Cap Cap f 0 D C B λ/4 A B C D D 2f 0 λ/2 B A B D C C D B 3f 0 3λ/4 B C D D C B A B C 4f 0 λ 250-GHz Oscillation Radiation Suppression and Energy Recycling of Harmonics 1-THz Radiation Unwanted harmonics (@ f 0, 2f 0, 3f 0 ) are canceled by near-field interference No Separate Filter is Needed 18

19 High-Density Radiation at 1 THz C Cap D C Slot Dipole Antenna B A B Cap D C B A B C D 4f 0 =1THz The 1-THz standing waves in all horizontal slots are in phase Effective backside radiation (η rad,sim =63%) On average, each oscillator (4x7 in total) drives 2 slot dipole antennas 91 Coherent Antennas (D λ/2) 19

20 Measurement Results: Frequency and Spectrum Power Supplies GND V B V CC Spectrum Analyzer (Tektronix RSA3303A) WR-3.4 Antenna IF Amplifier Chain WR-3.4 Mixer Measured f OSC,fund (GHz) f 0 = 16f LO + f offset V B (V) LO=15.8GHz Signal Generator (Keysight E8257D) Oscillation frequency is determined by a sub-harmonic SBD mixer Weak radiation leakage at f 0 Measured fundamental frequency: to GHz 4f 0 output: 1.01 to THz 20

21 Measurement Results: Radiated Power The radiated power is measured by a calibrated WR-1.0 zero-biased diode detector Measured total radiated power: 80 μw Measured beam directivity: 24 dbi (θ -3dB =11 ) Measured EIRP: 20 mw Normalized Received Power (db) Normalized Received Power (db) 0 Simulation Measurement H-Plane Phi (degree) 0 Simulation Measurement E-Plane Theta (degree) 21

22 Measurement Results: Radiated Power Function Generator GND V B (30Hz) Power Supply V CC Trigger Signal TK Processing Unit Heater PC TK Powermeter The measured radiated power is further verified by a photo-acoustic (TK) power meter with large aperture 22

23 Comparison with the State-of-the-Arts in Silicon [RFIC 2017] The achieved radiated power is 10x higher than prior siliconbased radiation sources in the mid-thz range 100x higher EIRP than prior arts Even larger scale with higher power should be possible 23

24 Outline Background Homogeneous Array: 1-THz Radiation Source Multi-Functional Mesh Structure Chip Prototype in SiGe and Measurement Results Heterogeneous Array: 220-to-320GHz Frequency-Comb Spectrometer High-Parallelism Architecture and THz Molecular Probing Module Chip Prototype in CMOS and Measurement Results Gas-Sensing Demonstration Conclusion 24

25 Wave-Matter Interactions for Material Sensing 25

26 THz Spectrometer for Gas Sensing [Source: HITRAN.org] Molecule Frequency (GHz) Toxic? Flammable? Carbon Monoxide (CO) Y Y Sulfur Dioxide (SO 2 ) Hydrogen Cyanide (HCN) Y Hydrogen Sulfide (H 2 S) Y Nitric Oxide (NO) Y Nitrogen Dioxide (NO 2 ) Y Nitric Acid (HNO 3 ) Y Ammonia (NH3) Y Carbonyl Sulfide (OCS) Y Y Ethylene Oxide (C 2 H 4 O) Y Acrolein (C 3 H 4 O) Y Methyl Mercaptan (CH 3 SH) Y Methyl Isocyanate (CH 3 NCO) Y Methyl Chloride (CH 3 Cl) Y Y Methanol (CH 3 OH) Y Y Acetone (CH 3 COCH 3 ) Y Y Acrylonitrile (C 2 H 3 CN) Y Y Transmittance (%) J= J O 12 C 32 S Absorption Intensity: Frequency (THz) Quantum Number 2J + 1 hbe hbj(j+1)/kt γ = kt 100% 85% 70% Frequency Offset From GHz (MHz) Wide Detection Range High Sensitivity High Selectivity 26

27 Dual-THz-Comb Spectrometer Conventional single-tone sensing scheme Bandwidth-efficiency tradeoff Long scanning time (~3 hours for 100-GHz bandwidth) Transmitter 220 f (GHz) f (GHz) 320 Receiver IF Our scheme using bilateral THz frequency combs Each circuit block maintains peak performance in a narrow band Simultaneous scanning using 20 comb lines (>20x increased speed) THz Comb A IF A,-n ~IF A,n f (GHz) f (GHz) 320 Spectrum of Comb A Spectrum of Comb B f IF THz Comb B 27 IF B,-n ~IF B,n-1

28 220-to-320GHz Comb-Based CMOS Spectrometer CMOS chip [C. Wang and R. Han, IEEE ISSCC, Feb. 2017] Hemispheric silicon lens 10 molecular-probing THz transceivers Key technology: multi-function, energy-efficient electromagnetic structures Seamless coverage of the 220 to 320 GHz band with khz resolution 28

29 Operation of the Transceiver Unit Core [C. Wang and R. Han, IEEE JSSC, Dec. 2017] Optimum device conditions created via a multi-functional EM structure Slot 1: resonator at f0 and antenna at 2f0 Slot 2: power recycle path at f0 and leakage blocker at 2f0 Simultaneous transmit/receive function 29

30 Time Per Sample Average Time Per Sample 20x CH1 CH2 CH3 CH4 CH17 CH18 CH19 CH20 High-Parallelism Broadband Architecture G max Transistor with DTL Feedback f min f max f min f max Original Transistor (W/L=12µ/60n) Single-Tone Spectrometer Dual-Comb Spectrometer η=43%, with DTL feedback η (%) η=18%, w/o feedback The relaxed tunability requirement allows the introduction of device positive feedback and higher device gain 43% simulated doubler conversion efficiency The total spectral scanning time is reduced by more than 20x, leading to high energy efficiency 30

31 2mm CMOS Chip Prototype Testing Board 3 mm WR-3 Even- Harmonic Mixer Setup for Radiation Spectrum and Pattern Testing TSMC 65nm bulk CMOS process (f max =250GHz) Chip area: 2 3mm 2 10 transceivers (doubler+receiver+antenna), 9 mixers, 40 amplifiers, operating at 0.1~0.3 THz DC power: 1.7 W 31

32 Experimental Results Span=10kHz RBW=10Hz Measured Down-converted IF Spectra of all Comb Lines Spectrum of a Comb Line at 265GHz Average Phase Noise: 1MHz Antenna Pattern of One Line (265GHz) 32

33 Experimental Results Effective Isotopically-Radiated Power Noise Figure of Each Channel (SSB, Antenna Loss Included) This work Total radiated power of the 10 comb lines: 5.2 mw Highest in silicon Minimum detectable signal: 0.1 fw (-130 τ=1 ms ISSCC TST This work This P work ISSCC TST BW ISSCC ISSCC TST RFIC P BW JSSC ISSCC 2015 ISSCC P RFIC RFIC 2015 BW ISSCC JSSC ISSCC CSICS RFIC TST MTT RFIC 2012 ISSCC JSSC CSICS ISSCC TST MTT RFIC ISSCC CSICS 2016 TST MTT 2012 ISSCC Radiated On-wafer measured with an On-wafer measured with an Radiated assumed assumed 50% radiation 50% radiation efficiency efficiency Radiated On-wafer measured with an assumed 50% radiation efficiency 33

34 Amplitude Spectroscopy Demonstration Output Spectral line L=70 cm, Pressure =3 Pa Acetonitrile (CH 3 CN) Time Time f m Freq WM input f ref +Δf/6 sin(2πf m t) Comb A Gas Chamber GPIB Comb B f ref f IF /6 Signal Source f m Signal Source IF i GPIB f m 2f m f IF Laptop Lock-in amplifier Detector BPF LNA Low pressure is applied to eliminate the spectral broadening due to the inter-molecular collisions Wavelength modulation is used to reduce the impacts of the standing wave inside the gas chamber 34

35 Phase Shift (Degree) Spectroscopy Results CH 3 CN O C S 1st-Order Derivative of Transmission (a.u.) Frequency (GHz) Sensitivity: 11 ppm for OCS, 14 ppm for CH 3 CN, 3 ppm for HCN ppt with standard gas pre-concentration Any polar molecule heavier than HCN can be detected Spectral linewidth is ~1MHz, leading to absolute specificity OCS SNR Pressure CH 3 CN BW=78Hz

36 Conclusions Using CMOS/BiCMOS device technologies not only enables THz frontend + analog/digital baseband integration, but may also directly enhance the THz-circuit performance Homogeneous arrays: high-density coherent wave interference Large total radiated power Ultra-narrow beam generation Heterogeneous arrays: high-parallelism EM spectral sensing Broadband coverage Optimal energy efficiency Key technology: versatile THz circuits with multi-functional structures A unified design framework: device, circuit, electromagnetism and architecture, all rolled into one 36

37 Acknowledgement Other Group Members: M. Kim, M. Ibrahim, M. I. Khan, X. Yi, J. Mawdesley, J. Maclver, Z. Wang Collaborators: B. Perkins (MIT Lincoln Lab), S. Coy (MIT), Q. Hu (MIT), M. Kaynak (IHP) Sponsors: 37

38 Large-Scale Terahertz Active Arrays in Silicon Using Highly-Versatile Electromagnetic Structures Cheng Wang, Zhi Hu, Guo Zhang, Jack Holloway and Ruonan Han Dept. of Electrical Engineering and Computer Science Microsystem Technology Laboratories Massachusetts Institute of Technology