© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
A 77-79GHz Doppler Radar A 77-79GHz Doppler Radar Transceiver in SiliconTransceiver in Silicon
Sean T. Nicolson1, Pascal Chevalier2, Alain Chantre2,Bernard Sautreuil2, & Sorin P. Voinigescu1
1) Edward S. Rogers, Sr. Dept. of Electrical & Comp. Eng., University of Toronto, Toronto, ON M5S 3G4, Canada
2) STMicroelectronics, 850 rue Jean Monnet, F-38926 Crolles, France
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
OutlineOutline
• Motivation and applications of Doppler radar
• Transceiver architecture and implementation challenges
• Circuit design and layout (top level & circuits blocks)
• Fabrication technology and measurement results
• Detection of the Doppler shift
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Doppler Radar ReviewDoppler Radar Review• Track range and velocity of a target without amplitude info
Target range:
Target velocity:
transceiver
hostile channel
transmitted carrier (fC)
fC ± f
round trip delay ()
Doppler shift
moving target (v)
reflected signal
cr2
1
Cf
fcv
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Automotive Radar ApplicationsAutomotive Radar Applications• Automotive applications of Doppler radar
• Transceiver requirements:– Long range, high PTX (not CMOS)– On-chip DSP (need CMOS)– low cost, single chip (many per car)– Low area, low power (phased arrays)
• SiGe BiCMOS, direct conversion
150-200mv < 1km/h
< 1 part/billion sensitivity
c = 3×108
v = 1 km/h fC = 77GHz
f = 70Hz
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Implementation of the TransceiverImplementation of the Transceiver
• Single die for receiver and transmitter• Tuned clock tree used to distribute VCO signal• Frequency division at 77GHz using a static divider• All circuit blocks use < 2.5V supply (except divider uses 3.3V)
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Implementation of the TransceiverImplementation of the Transceiver
• Single die for receiver and transmitter• Tuned clock tree used to distribute VCO signal• Frequency division at 77GHz using a static divider• All circuit blocks use < 2.5V supply (except divider uses 3.3V)
LNA supply
VCO supply
Digital supply
Complete power and bias isolation
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Low-noise AmplifierLow-noise Amplifier• 3-stage design, add R1 to de-Q the final stage.
• Noise & Z matching inc. CPAD [Nicolson et al., CSICS 2006]
• All circuit blocks discussed in [Nicolson et al., IMS 2007]
250m
1pF decoupling caps
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Clock Buffer DesignClock Buffer Design• Cascode topology is chosen for the clock buffer
– high reverse isolation (i.e. low S12)– Broadband, low gain (degeneration and resistive loading)
• Parameterized design of fixed size buffer to variable size load– Q1, Q2, LC, and LE are fixed– R1/R2 chosen for biasing, R1//R2 chosen to set Q– LINT and C1 chosen to match to particular HBT size
matching interface
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Layout for Isolation & Bias DistributionLayout for Isolation & Bias Distribution• Layout methodology systematically addresses:
– Isolation of circuit blocks– High-C, low-R, low-L power, ground & bias planes– N-well and p-sub contacts for isolation in the substrate
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Top Level LayoutTop Level Layout
1.3mm
0.9mm
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Fabrication TechnologyFabrication Technology• Two technologies with identical BEOL
– wE = 0.13m with 170/200 GHz fT/fMAX
– wE = 0.13m with 230/290 GHz fT/fMAX
Technology info in:[P. Chevalier et al., BCTM 2005]
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Transmitter Output PowerTransmitter Output Power• Transmitter POUT vs. LO and T (230/300GHz fT/fMAX process)
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Optimal Biasing for SiGe HBT PAsOptimal Biasing for SiGe HBT PAs• SiGe HBT power amplifier PAE, PSAT, and P1dB vs. bias
– All reach a maximum at the same current density
1.5V
1.8V
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Receiver Conversion GainReceiver Conversion Gain• Peak conversion gain of 40dB, -3dB bandwidth is 10GHz
83GHz LO
81GHz LO
78GHz LO
Co
nv
ers
ion
Gai
n [
dB
]
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Receiver Conversion GainReceiver Conversion Gain• IP1dB of -35dBm and OP1dB of +3dBm at 25°C, 2.5V supply
• IP1dB of -30dBm and OP1dB of 0dBm at 100°C, 2.5V supply
83GHz LO
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
LNA Input MatchLNA Input Match• S11 better than -15dB from 81GHz to 94GHz
• S11 does not degrade significantly with current density
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Receiver Noise Figure @ 1GHz IFReceiver Noise Figure @ 1GHz IF• JOPT is constant versus temperature bias with const. IC
• 3.85dB NF at 25°C in receiver with 300GHz fMAX HBT
81.6GHz LO
3.85 dB
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Receiver Noise Figure versus IFReceiver Noise Figure versus IF• Maximum NF of 4.7dB at 2.5GHz IF, 81.6GHz LO
4.7 dB
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Doppler Radar Experimental SetupDoppler Radar Experimental Setup
> 40cm 110GHz coax
110GHz probe & cap
110GHz probe & cap
15cm 110GHzcoax
horn antennae(20dB gain each)
Bias
BNC cables
30Hz DC block
3kHzLo-Pass
Scope
IAACL = 40dB
Target0.25m2
6m range
4dB RX loss
12dB TX loss107dB channel loss
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Doppler Radar Experimental SetupDoppler Radar Experimental Setup
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Doppler Radar Experimental SetupDoppler Radar Experimental Setup
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Doppler Radar Experimental SetupDoppler Radar Experimental Setup
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Doppler Radar Experimental SetupDoppler Radar Experimental Setup
> 40cm of 110GHz coaxial cable
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Example Doppler SignalExample Doppler Signal• 55Hz Doppler signal (target moving at 0.75km/h)
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Doppler Radar VideoDoppler Radar Video• Human target walking forward & backward at varying speed
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
Comparison To Other WorkComparison To Other Work• This work: bottom row
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
ConclusionsConclusions• First single-chip silicon 82GHz direct conversion transceiver
– Fundamental VCO – Verified to operate at 100°C using 2.5V supply (3.3V for divider)
Improved VCO will obtain improved performance over temperature
– Static frequency divider at 82GHz– Successfully detected a 55Hz Doppler shift at 6m range– 3.9 – 4.7dB noise figure with 82GHz LO and 0.5 – 4GHz IF
record for W-Band CMOS/SiGe receivers
© Sean Nicolson, BCTM 2006© Sean Nicolson, BCTM 2006© Sean Nicolson, 2007
AcknowledgementsAcknowledgements• K. Yau for help with measurements• STMicroelectronics for fabrication of circuits & test structures• J. Pristupa, and E. Distefano for CAD & network support• CITO & NSERC for funding