1 A CMOS UWB Camera with 7x7 Simultaneous Active Pixels Ta-Shun Chu and Hossein Hashemi University of Southern California, Los Angeles, CA
2 Outline Introduction Multi-Beam Architectures for Antenna Array A CMOS UWB Camera UWB Camera Measurement Results Conclusion
Motivation 3 Optical Camera RF Camera Light Beam Optical Lens Light Sensor Electromagnetic Beams Antenna Array Microwave Lens Detector Array RF Camera can reconstruct images by using active or passive sensing. RF Camera allows for imaging through optically opaque objects.
Antenna Array Principle 4 τ Timed Array Large Instantaneous BW Constant Group delay Phased Array Small Instantaneous BW Constant Phase Shift RF in τ τ τ RF out Phase Group Delay Frequency Frequency Group Delay Phase Frequency Frequency Note: Broadband phased array is not equal to broadband timed array.
Scanning and Multi-Beam Antenna Arrays 5 Scanning Antenna Array Multi-Beam Staring Array Beam 1 Beam 2 Beam 3 Beam 4 Beam 5 RF in1 RF in2 RF in3 RF in4 RF in1 RF in2 RF in3 RF in4 τ τ τ τ Multi-Beam Matrix RF out RF out1 RF out2 RF out3 RF out4 RF out5 Multi-beam staring array reduces the image capture time significantly.
6 Outline Introduction Multi-Beam Architectures for Antenna Array A CMOS UWB Camera UWB Camera Measurement Results Conclusion
Microwave Lens Multi-Beam Structure 7 1D Array Beam 1 Beam 2 Beam 3 Outer Lens Inner Lens RF Cable Parallel Plate Focal Arc I/O 3 I/O 2 I/O 1
Microwave Lens Multi-Beam Structure 7 1D Array 2D Array Beam 1 Beam 2 Beam 3 Outer Lens Inner Lens RF Cable Parallel Plate Focal Arc I/O 3 I/O 2 I/O 1 z x y
Conventional Circuit Multi-Beam Matrix 8 1D Array Beam 1 Beam 2 Beam 3 2τ τ τ τ τ 2τ I/O 1 I/O 2 I/O 3
Conventional Circuit Multi-Beam Matrix 8 1D Array 2D Array Beam 1 Beam 2 Beam 3 2τ τ τ τ τ 2τ I/O 1 I/O 2 I/O 3 z x y
Blass Multi-Beam Matrix 9 1D Array Beam 1 Beam 2 Beam 3 #1 #2 I/O 1 τ τ 2τ 2τ 3τ 3τ I/O 2 2τ I/O 3
Blass Multi-Beam Matrix 9 1D Array 2D Array Beam 1 Beam 2 Beam 3 #1 #2 I/O 1 τ τ 2τ 2τ 3τ 3τ I/O 2 2τ I/O 3 z x y
The Proposed Multi-Beam Matrix 10 1D Array Beam 1 Beam 2 Beam 3 #1 #2 τ τ τ τ I/O 3 I/O 2 I/O 1
The Proposed Multi-Beam Matrix 10 1D Array 2D Array Beam 1 Beam 2 Beam 3 #1 #2 τ τ τ τ I/O 3 I/O 2 I/O 1 z x y
Comparison of Multi-Beam Arrays 11 2 inputs 3 outputs 4 inputs 5 outputs 2X2 inputs 3X3 outputs 4X4 inputs 5X5 outputs Conventional Multi-beam Matrix Blass Multi-beam Matrix The Proposed Multi-beam Matrix 8τ 7τ 2τ 56τ 70τ 27τ 40τ 35τ 10τ 504τ 630τ 243τ Complexity of 2D Array
12 Outline Introduction Multi-Beam Architectures for Antenna Array A CMOS UWB Camera UWB Camera Measurement Results Conclusion
Proposed UWB Camera 13 Antenna LNA
Proposed UWB Camera 13 Antenna LNA
Proposed UWB Camera 13 Antenna LNA Transconductance Amplifier
Proposed UWB Camera 13 Antenna LNA Unit Delay Cell ( τ ) Transconductance Amplifier Delay Line Termination
Proposed UWB Camera 13 Antenna LNA Unit Delay Cell ( τ ) Transconductance Amplifier Detector Driver (RF Buffer) Delay Line Termination
Proposed UWB Camera 13 Antenna LNA Unit Delay Cell ( τ ) Transconductance Amplifier Detector Driver (RF Buffer) Detector Array (7X7 Pixels) Delay Line Termination
Proposed UWB Camera 13 Electromagnetic Beams (7X7 Directions) Antenna LNA Unit Delay Cell ( τ ) Transconductance Amplifier Detector Driver (RF Buffer) Detector Array (7X7 Pixels) Delay Line Termination
Signal Flow for Pixel 44 14 X-direction Y-direction 4τ RF in11 Delay In 11 Out 44 = 4τ + 4τ = 8τ Delay In 12 Out 44 = 4τ + 4τ = 8τ Delay In 21 Out 44 = 4τ + 4τ = 8τ Delay In 22 Out 44 = 4τ + 4τ = 8τ 4τ Z RF in21 RF in12 X Y 4τ RF in22 4τ
Signal Flow for Pixel 52 15 X-direction Y-direction 5τ RF in11 Delay In 11 Out 52 = 5τ + 2τ = 7τ Delay In 12 Out 52 = 5τ + 6τ = 11τ Delay In 21 Out 52 = 3τ + 2τ = 5τ Delay In 22 Out 52 = 3τ + 6τ = 9τ 3τ Z RF in21 RF in12 X Y 2τ 6τ RF in22
UWB Camera Block Diagram 16 RF in11 RF in12 LNA VGA Bias Circuit Transconductance Amplifier Detector Driver (RF Buffer) Energy Detector Digital Controller RF in21 RF in22
Embedded Equalizer 17 Original-Embedded Equalizer Optimal-Embedded Equalizer Array Gain Array Gain Array Gain Array Gain Group Delay Gain Frequency Frequency Group Delay Gain Frequency Frequency Group Delay Gain Frequency Frequency Group Delay Gain Frequency Frequency Embedded equalizer maintains the same array gain for all directions.
UWB Front-end Design 18 Vdd Mf Lsp Pad 50Ω M1 Ls M2 Delay Line Pad Lg Vb1 Vin+ Vin- UWB LNA Vb2 Vb3 Vb4 3-Stage UWB VGA -3dB bandwidth Power gain S11 (1GHz-15GHz) Noise figure 1 db Compression Point (input power) Current Consumption 17GHz 19dB <-10dB <4.5dB -19dBm@1GHz, -22dBm@15GHz 60mA @1.5V
UWB Front-End Measurement Results 19 30 6 S21 (db) 25 20 15 10 5 NF (db) 5 4 3 2 0 1 3 5 7 9 11 13 15 17 Frequency (GHz) 1 1 3 5 7 9 11 13 15 17 Frequency (GHz) Group Delay (ps) 100 80 60 40 20 0 1 3 5 7 9 11 13 15 17 Frequency (GHz) S11(dB) 0-5 -10-15 -20 1 3 5 7 9 11 13 15 17 Frequency (GHz)
Amplifier and Driver Design 20 Vdd + _ Vout Lm Vdd Pad Vb5 Vb6 Transconductance Amplifier 30mS transconductance Gain with 3.4mA @ 1.5V Detector Driver (RF Buffer) 2dB Voltage Gain with 3.6mA @ 1.5V
Energy Detector Design 21 Input Output Squarer Lowpass filter Integrator 3-Bit ADC Vdd Vo1 Vc1 Vo2 + Vb8 Cp Vc2 Vo3 Vin _ Vc3 Vb7 Energy detector has low power and consumes small area.
Pulse Energy Detector Measurement Results Monocycle Pulser Monocycle Pulser 180 Hybrid Detector Driver Monocycle Pulser 180 Hybrid Detector Driver Squarer Squarer Integrator Integrator Digital Oscilloscope 50Ω Digital Oscilloscope 50Ω Digital Oscilloscope 50Ω 1nF Voltage (mv) Voltage (mv) Voltage (mv) 40 20 0-20 -40 0 1 2 3 4 5 4 2 0-2 -4-6 0 1 2 3 4 5 4 3 2 1 0 Time (nsec) Time (nsec) -1 0 1 2 3 4 5 Time (nsec) 22
23 Outline Introduction Multi-Beam Architectures for Antenna Array A CMOS UWB Camera UWB Camera Measurement Results Conclusion
Die Microphotograph 24 RFin11 RFin12 UWB Front-End Horizontal Delay Line Vertical Delay Line Unit Delay Cell RF Output Buffer UWB Gm Cell 4.1mm Pulse Energy Detector Digital Control Unit RFin21 4.1mm RFin22 Implemented in 0.13μm CMOS with 8 metal layers.
Single-Channel Measurements for Pixel 44 25 Voltage (mv) RFin21 6 4 2 0-2 -4-6 RFin11 RFin22 Time Domain Measurement Input Monocycle 0 200 400 600 800 1000 Time (psec) RFin12 Group Delay (psec) Power Gain (db) 30 25 20 15 10 5 0 250 200 150 100 50 0 Frequency Domain Measurement Array Power Gain 1 3 5 7 9 11 13 15 17 Frequency (GHz) 1 3 5 7 9 11 13 15 17 Frequency (GHz)
Single-Channel Measurements for Pixel 52 26 Voltage (mv) RFin21 6 4 2 0-2 -4-6 RFin11 RFin22 Time Domain Measurement Input Monocycle 0 200 400 600 800 1000 Time (psec) RFin12 Group Delay (psec) Power Gain (db) Frequency Domain Measurement 30 Array Power Gain 25 20 15 10 5 0 1 3 5 7 9 11 13 15 17 Frequency (GHz) 250 200 150 100 50 0 1 3 5 7 9 11 13 15 17 Frequency (GHz)
Single-Channel Measurements for Pixel 71 27 Voltage (mv) RFin21 6 4 2 0-2 -4-6 RFin11 RFin22 Time Domain Measurement Input Monocycle 0 200 400 600 800 1000 Time (psec) RFin12 Group Delay (psec) Power Gain (db) Frequency Domain Measurement 30 Array Power Gain 25 20 15 10 5 0 1 3 5 7 9 11 13 15 17 Frequency (GHz) 250 200 150 100 50 0 1 3 5 7 9 11 13 15 17 Frequency (GHz)
Noise Figure and Linearity Measurements 28 7 6 NF (db) 5 4 3 1 3 5 7 9 11 13 15 17 Frequency (GHz) -5-10 Pout (dbm) -15-20 -25-30 -35 1GHz 8GHz 15GHz -40-35 -30-25 -20-15 -10 Pin (dbm)
Synthesized Array Patterns 29 Pixel 41 Pixel 42 Pixel 43 Pixel 44 Pixel 51 Pixel 52 Pixel 53 z RF in11 RF in12 y y Pixel 61 Pixel 62 x x 41 42 43 44 51 52 53 61 62 71 Pixel 71 RF in21 RF in22
Wireless Measurement Setup 30 Receiving Antenna Array HP 11966G Conical Log Spiral Antenna 3cm UWB Camera Chip 3cm Pulsed Sinusoid Generator Front Side Back Side Z. Low, et. al, AWPL 05 Reported UWB Camera measurements correspond to active receiving mode with 4cm antenna spacing.
Wireless Measurement Result 31 Theoretical Measured 1 1 0.7 0.7 0.4 0.4 Maximum intensity is at the center pixel (pixel 44).
Wireless Measurement Result 32 Theoretical Measured 1 1 0.6 0.6 0.2 0.2 Maximum intensity is at the bottom the left corner pixel (pixel 71).
Measurement Performance Summary 33 UWB Front-End (LNA + VGA) -3dB bandwidth 17GHz Power gain 19dB S11 (1GHz 15GHz) < -10dB Noise-Figure (1GHz 15GHz) < 4.5dB 1 db Compression Point (input power) -19dBm@1GHz, -22dBm@15GHz Power dissipation 60mA @1.5V Complete 4-Channel 2D Multi-beam Array -3dB Bandwidth 15GHz Total array gain 24dB Noise-Figure (1GHz 14GHz) < 5.8dB (single channel worst case) 1 db Compression Point (input power) -24dBm@1GHz, -26dBm@15GHz UWB true time delay resolution 17.5ps UWB Camera spatial resolution 10 (antenna separation = 3cm) Total number of available beams 7X7=49 (Simultaneously) Power dissipation 630mA@1.5V Total number of on-chip spiral inductors 220 Technology 0.13µm CMOS Die Area 4.1mm x 4.1mm
Conclusions 34 Ultra wideband multi-beam arrays are strong candidates for high resolution radar and imaging applications. The proposed broadband multi-beam array architecture is introduced that is suitable for integrated circuits layout and reduces the chip area significantly. The first single-chip Ultra wideband Camera with 2X2 antennas and 7X7 simultaneous pixels is demonstrated in a 0.13μm CMOS technology.
Acknowledgement 35 This work was supported by Boeing Phantom Works, Seattle, WA National Science Foundation Our thanks to Fong Shi and Michael Foster, Boeing Phantom Works W-F. Yeh, S-W. Feng, Ray Chen, C.Y. Lee, and our group members, USC