Millimeter-Wave and Terahertz Systems-on-Chip for Radio, Radar and Imaging Applications RFIC Mini-Symposium, Tela Aviv University, July 3 2012 Prof. M.-C. Frank Chang University of California, Los Angeles Email: mfchang@ee.ucla.edu 1
Outline Mm-Wave and Terahertz Systems-on-Chip Ultra-high-speed (>10Gbps) Near-Field-Communication (NFC) Systems Broadband (57-64GHz) Self-Healing Radio-on-a-chip Mm-Wave to Terahertz (144-495GHz) Radar and Imaging Common Needs in Digital Controlled Artificial Dielectric (DiCAD) with Reconfigurable/Tunable Permittivity Historical Artificial Dielectric Synthesizing DiCAD in Deep-Scaled CMOS Reconfigurable/Scalable DiCAD Circuit Designs Linear phase shift and Impedance Matching Direct frequency modulation/de-modulation Broadband frequency synthesis High PAE power amplifier
Near Field Communication Systems
Near Field Coupled WaveConnector Near-field-Communication at multi-giga-bit/sec Ultra-high data rate (>10gbps) for short distance and secured communications Protocol-transparent, near-universal applications Ends the electrical and mechanical compromises
WaveConnector in Action Link demonstration Tiny, <1mm 2 chips Smaller than the chip caps! Mounted along PCB edges 60 GHz carrier, ASK modulated Error-free operation over 10Gb/s up to a few centimeters Click image to play video 1.2mm RX chip TX chip 1.2mm Closeup showing chips mounted face-up and wire-bonded to PCB 0.6mm 0.6mm
60GHz Self-Healing Radio-on-a-chip for IEEE 802.11ad and WIGIG
60GHz Radio-on-a-Chip (RoC) UCLA students designing Self-Healing Reconfigurable 4Gigabit/sec Radio-on-a-Chip (RoC) for IEEE 15.3c, WIGIG, WLAN 11ad system applications. The 65nm CMOS RoC contains 57-65GHz Transmitter, Receiver, Frequency Synthesizer, ADC/DAC, Digital Baseband.. About 25million Transistors
57-64GHz Radio-on-a-Chip Feature Size Value 4.0 x 4.0 mm Pads 145 On-Chip Cap 285 pf Power Domains 44 RF Control 255 RF Frequency BB Clock 57-65 GHz 2.0 GHz In Color!
60GHz Radio-on-a-Chip System Performance Metrics/Yield * Based on Test Results from Ten Assembled Die-on-Boards Metric Unit Phase I GNG Performer Status to Date Achieved Baseline Yield Post-Healing Yield Performer Defined Metrics Receiver (X) NF db <6 4.6(Healed)* 0%* 100%* Output Bandwidth GHz 1.2 >1.22- BL-OK* 100%* 100%* Rx OIM3 dbc -40 <-41.3 BL-OK* 100%* 100%* Transmitter P1dB dbm 10 >12.5 BL-OK* 100%* 100%* TX OIM3 dbc -40-43 (Healed)* 0%* 100%* Synthesizer Phase Noise dbc -90@ 1MHz -94@1MHz BL-OK* 100%* 100%* Channel Frequency GHz 58.32 + n 2.16 N=0 3 Hit all tones with sufficient VCO margin* 100%* 100%* I/Q mismatch dbc -40-44.6 (Healed)* 0%* 100%* ADC ENOB Bit > 5.5 >5.8 BL-OK* 100%* 100%* Program GNG Metrics Performance Yield (1 % 75 100* 0%* 100* Power Consumption Overhead % 10 3.69%* 785mW* 785+29mW* BL-OK*: Baseline Circuit Performance Met Specs Without Healing
60GHz 4Gbps Self-Healing Radio Biasing Self-Healing RF Control Clocking Baseline
Before and After: Image Healing Carrier Carrier Carrier Image Image Image -40 dbc Initial State Phase Healing Phase + Amplitude + DC
TX LO and Image (IQ) Healing System Key Components 3 4 1 2 1. Knobs: the phase offset, relative gains and DC offset between TX I&Q channel are controlled by the IQ unit. 2. The DAC controller provides test tones for 1 tone and two tone testing. 3. The envelope sensor at the TX output captures the tone information from the 60GHz output spectrum. 4. The parameter estimator evaluates and returns the relative amplitudes of LO leakage, and Image tone power.
Code Sweep of Phase Correction vs. Image Phase Sweep Result of code sweep clearly shows that there is a single local minimum corresponding to true zero phase offset between I and Q. IQ Phase offset of transmitter seems to be about 7-10 degrees. Image level is still not in spec because the amplitude mismatch still exists. This must also be healed.
Code Sweep of Amplitude Correction vs. Image Amplitude Sweep Once the phase is correctly set the amplitude must also be adjusted to obtain zero mismatch between I and Q. The I channel is held at 255 amplitude so there is about a 10 LSB amplitude mismatch. The image level is can now reach specification.
Code Sweep of DC Offset Control vs. LO Leak DC Offset Sweep Result of code sweep clearly shows that there is a single local minimum corresponding to zero DC offset between I and Q. Baseline already meets GNG requirements without applying a correction offset.
Linear Extrapolation with Cautious Control Image and LO Healing Algorithm We expect the mismatch will be less than 20 degrees for IQ angle, less than 50 LSBs for amplitude mismatch and less than 50 LSBs for LO leakage from DC and so we do linear extrapolation to first estimate the correct phase setting. After the linear estimation we can do a local 4% of range sweep around the estimated value with a basic search in a small solution space. First heal phase, then amplitude, then DC offset
100% Yield from Image Tone Healing
100% Yield from TX OIM3 Healing
100% Yield from Noise Figure Healing
Mm-Wave to Terahertz (144-495GHz) Imaging and Radar Systems
183GHz CMOS Active Imager Electrical Measurements Imaging Results Measurement Value Frequency 183 GHz NF 9.9 db Power 13.5mW Sensitivity -72 dbm Area 13100 um 2 NEP 1.5fw/Hz 0.5 Gain 1.3ms/W Frequency Response Time-Encoded Output Sample-Targets (metals and non-metals) A) Metallic Wrench B) Computer floppy disk C) Football D) Roll of tape *All items were concealed in cardboard boxes
Digital Regeneration Receiver Injecting fundamental power into an oscillator shortens the start-up time Adding a digital latch circuit allows the oscillator to restart each clock. When the oscillator starts it triggers the digital reset creating a pulse width proportional to input power
DRR Prototype Test Results
Tri-Color (350/200/50GHz) IRR Imager (Inter-modulated Regenerative Receiver) First reported architecture for RX to operate above F max Fastest reported silicon receiver (SiGe or CMOS) First multi-band sub-millimeter-wave receiver (3 bands) Chopper Sync RX 350 GHz Chopper Response CMOS Tri-band Receiver 24
495 GHz CMOS Super-Regenerative Receiver 495 GHz Regenerative Receiver based on 40nm TSMC CMOS technology with total power consumption of 5mW under 1V supply voltage 495 GHz Chopper Signal 495GHz Image Capture Terahertz System Demonstrations 1. Sensitivity measurement of antenna-less 245 GHz http://www.ee.ucla.edu/~atang/250_demo.mp4 2. 495 GHz antenna-less imager http://www.ee.ucla.edu/~atang/494_demo.mp4 3. Imaging Radar Demo http://www.ee.ucla.edu/~atang/radar_demo.mp4
Reflective Mode Active Imaging Target is placed at a stand-off distance from imaging system containing source and detector and reflection is measured. The system must accommodate 2X the free space path loss of a regular radio link.
Low Physical Reflection Diversity 350 GHz 28 dbm Bottle Acrylic Backdrop Metal Stand Metal Rail The above is illuminated with 28 dbm from a 350 GHz TWT source and detected with a 25fw/Hz 0.5 receiver. Even with high power and low NEP the system is ineffective because the reflection diversity is too low (metal, plastic & fluid all have similar reflection coefficients).
Incidence Angle is Critical 0º Incidence 350 GHz 2º Incidence 350 GHz Rotating the target even off-axis eliminates the useful information in the image capture because the energy is not reflected back to the receiver [1]. [1] Ken Cooper et.al. (NASA Jet Propulsion Lab) " Penetrating 3D Imaging at 4 and 25m Range Using a Sub-millimeter-Wave Radar IEEE MTT 2008 V56 #12.
144 GHz CMOS Sub-Ranging 3D Imaging Radar with <0.7cm Depth Resolution First mm-wave 3D imaging radar in silicon! Quasi-Optical Setup for 144 GHz Radar Presented at ISSCC 2012
144 GHz CMOS Sub-Carrier SAR 3D Imaging Radar Results Presented at ISSCC 2012 30
Required mm-wave Device/Circuit Innovations Topology (circuit Architecture) to secure sufficient signal headroom Inter-stage circuitry to optimize I/O impedance and enhance signal gain High permittivity artificial dielectric to shrink dimensions of passives and reduce transmission / resonator / substrate loss over conductive Si substrate Embedded sensors/actuators/controller for selfdiagnosis/healing to optimize system performance yield and counter system performance aging
Historical Artificial Dielectric W.E. Kock, Metallic delay lenses, Bell Syst. Tech. J, vol. 27, pp. 58-82, 1948
Historical Artificial Dielectric (II)
Induced Dipole Moment Boosts Permittivity in Capacitor b φ = E 2 Q+q b E 2 b E p -q q φ = b E 2 -Q-q b E 2 Unloaded cell Capacitance C 0 = Q Eb Permittivity boost-factor Loaded cell Capacitance κ = C 0 C 0 Q + q C 0 = Eb
Artificial Dielectric Array of identical conducting obstacles embedded in a dielectric medium Displaced charges on obstacles induce dipole field Permittivity boost-factor reduces resonant wavelength and resonator size E ε r Unit cell p x D z a P = Np = b p abc c y = ε E + P = κε E λmedium λad = κ
CMOS Artificial Dielectric l=λ/4 w s Transmission line guiding quasi-tem wave 0 C 0 = C 25 20 15 10 Cross-section view of E field vector E κ 5 p 0 t d 0.1 1 10 100 1000 d(µm)
Challenges in CMOS MM-Wave VCO High device flicker noise Large WL devices? p-mos? Low-Q lumped passives Skin effect Substrate loss Potential solutions Use distributed coplanar strip line resonator Enhance resonator s Q with on-chip artificial dielectric Outpu noise (A/ Hz) L Device Noises (IBM, 2003) n-mos p-mos SiGe HBTs ktfr ω P 0 ωm AlGaAs/GaAs HBT Frequency (Hz) Leeson s equation 0 ( ω ) = m 2 2 1 Q
VCO Die/Performance Resonator with embedded artificial dielectrics 100 0µm -94 dbc/hz @100kHz Offset Varactor area 150µm -107 dbc/hz @ 1MHz Offset
Performance Comparison Reference Process f 0 (GHz) V DD (V) P DC (mw) PN@1MHz (dbc/hz) FOM Die area (mm 2 ) This work 90nm CMOS 60 1 1.9-107 -200 0.015 J.Kim 1 MTT- S,2003 B.A. Floyd 2 RFIC,2004 InGaP/ GaAs HBT 60 3.5 158-93 -167 0.78 SiGe HBT 67 3 25-98 -181 - Y.Cho 3 RFIC,2005 R.Liu 4 ISSCC,2004 P.Huang 5 ISSCC,2005 0.18µm CMOS 0.25µm CMOS 0.13µm CMOS 53 2.1 27-97 -177 0.20 63 1.8 119-85 -160 0.32 57 1.2 8.4-70 -136 0.20
Digitally Controlled Artificial Dielectric (DiCAD) Switch network inserted midway along virtual ground of the artificial dielectric strip (NMOS, π-configuration) Result: Digital control of effective dielectric constant!
DiCAD as Analog Control Knob (a ) (b ) (c) (d) (e) (a) Two sections of 41.25um long DiCAD with 15 control switches each, under a differential TML with width of 22um and gap of 50um. The DiCAD bars are 5um wide with a pitch of 5.5um (space=0.5um); (b) for impedance match; (c) for impedance transformation; (d) for frequency selection; (e) for phase shift.
48GHz PLL Topology Type-II 3 rd order Integer-N PLL Programmable divide chain (512 to 992, in steps of 32) DiCAD-based mm-wave blocks
mm-wave Resonator Design Challenges Goal Minimise and Accurately for Parasitic Capacitance
DiCAD-Based Resonators DiCAD developed as a permittivityprogrammable transmission line Fundamental Trade-off Key Benefits: Easily modelled, characterised and simulated Reduces parasitic concerns Enables first-time right mm-wave design Enables fine digital frequency tuning CRatio
Additional Resonator Design Choice DiCAD employed in all mm-wave Blocks Ensures frequency alignment Resistor Array used as current source Reduces flicker noise
VCO Measurement Results (1) DiCAD controlled using 5-bit (32-state) thermometer code KVCO reduced below 1GHz/V across entire band 6 frequencies can be synthesized using 54MHz XO 43.2GHz, 44.928GHz, 46.656GHz, 48.384GHz, 50.112GHz and 51.84GHz
VCO Measurement Results (2) Distributed nature of DiCAD and use of thermometer codes results in a very linear digital tuning Varactor-size can be minimised
Die Micrograph (a) PLL Testchip (b) TRX Testchip
Comparison with State-of-the-Art [1] O. Richard et al., ISSCC 2010, pp. 252 253, Feb. 2010
DiCAD for Linear Phase Shifter Linear phase change from -50.6 o to -65.8 o Linear increase in ε eff from 18.8 to 32 at 61GHz 35% of physically available range switch resistance and capacitance limit performance Phase (S21) vs. freq. Phase, ε r,eff vs. digital state
Direct Frequency Vector Sum Modulator Take advantage of direct frequency architecture, and linear DiCAD Create and add two vectors in opposite quadrants to create sum vector that spans entire I-Q plane Quadrant Phase and Amplitude Shifters (QPAS) only need to work in a single quadrant.
DiCAD QPAS Design a dynamically matched amplifier with shunt/open DiCAD stubs and series L networks (similar to Hi-Lo P.S.) Control phase with DiCAD and amplitude with NMOS Switch Sequence State 1: 00 0001 State 2: 00 0011 State 3: 00 0111 State n: 11 1111
Measured Modulation States Measured QPAS shows coverage (S21) of entire quadrant QPAS is well-controlled, and evenly distributed Measured 256 2 total modulation points at 62.64GHz
DiCAD for Digital Constellations Measured (+) and ideal (o) constellation points. Static EVM < -31dB BPSK π/2 QPSK π/2 Star-8QAM π/2 16QAM
Summary Scalable SoC Designs based on Digital Controlled Artificial Dielectric (DiCAD) Synthesizing DiCAD in Deep-Scaled CMOS Reconfigurable/Scalable DiCAD Circuit Designs Linear phase shift and Impedance Matching Direct frequency modulation/de-modulation Broadband frequency synthesis High PAE power amplifier Extensive System Applications in mm-wave to Terahertz Spectra Ultra-high-speed (>10Gbps) Near-Field-Communication (NFC) Systems Broadband (57-64GHz) Self-Healing Radio-on-a-chip Mm-Wave to Terahertz (144-495GHz)Radar and Imaging