A CMOS UWB Camera with 7x7 Simultaneous Active Pixels

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

3

Motivation Optical Camera

RF Camera Light Sensor

Light Beam

Optical Lens

Microwave Electromagnetic Lens Beams Antenna Array

Detector Array

•RF Camera can reconstruct images by using active or passive sensing. •RF Camera allows for imaging through optically opaque objects.

4

Antenna Array Principle

RFout

Small Instantaneous BW

Constant Group delay

Constant Phase Shift

τ

Frequency

Frequency Group Delay

τ

Phase

τ

Large Instantaneous BW

Group Delay

RFin

Phased Array

Phase

τ

Timed Array

Frequency

Frequency

Note: Broadband phased array is not equal to broadband timed array.

5

Scanning and Multi-Beam Antenna Arrays Multi-Beam Staring Array

B 5

RFin2

4

RFin1

ea m

τ

τ

RFin4

Beam 3

τ

RFin3

1

2

RFin2

RFin1

am

am Be

Be

am Be

Scanning Antenna Array

RFin3

RFin4

τ Multi-Beam Matrix

RFout

RFout1 RFout2 RFout3 RFout4 RFout5

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

7

Microwave Lens Multi-Beam Structure 1D Array B e am 3

1

Beam 2

am Be

Outer Lens

RF Cable

Inner Lens

Parallel Plate Focal Arc

I/O 3

I/O 2

I/O 1

7

Microwave Lens Multi-Beam Structure 1D Array

2D Array B e am

3

1

Beam 2

am Be

Outer Lens

RF Cable

Inner Lens

Parallel Plate Focal Arc

I/O 3

I/O 2

I/O 1 z

x

y

8

Conventional Circuit Multi-Beam Matrix 1D Array

I/O 1

τ

3

1

τ

B e am

Beam 2

am Be

2τ

τ

I/O 2

τ

I/O 3

2τ

8

Conventional Circuit Multi-Beam Matrix 1D Array

I/O 1

τ

3

1

τ

B e am

Beam 2

am Be

2τ

τ

I/O 2

2D Array

τ

2τ

I/O 3

z

x

y

9

Blass Multi-Beam Matrix 1D Array B e am 3

1

Beam 2

am Be

#2

#1

I/O 1

τ τ

2τ 2τ 2τ

3τ I/O 2 3τ I/O 3

9

Blass Multi-Beam Matrix 1D Array

2D Array B e am

3

1

Beam 2

am Be

#2

#1

I/O 1

τ τ

2τ 2τ 2τ

3τ I/O 2 3τ I/O 3

z

x

y

10

The Proposed Multi-Beam Matrix 1D Array B e am

Beam 2

3

am Be 1

#1

#2

τ

τ

I/O 3

τ

I/O 2

τ

I/O 1

10

The Proposed Multi-Beam Matrix 1D Array

2D Array B e am

Beam 2

3

am Be 1

#1

#2

τ

τ

I/O 3

τ

I/O 2

τ

I/O 1

z

x

y

11

Comparison of Multi-Beam Arrays Conventional Multi-beam Matrix

Blass Multi-beam Matrix

The Proposed Multi-beam Matrix

2 inputs 3 outputs

8τ

7τ

2τ

4 inputs 5 outputs

56τ

70τ

27τ

2X2 inputs 3X3 outputs

40τ

35τ

10τ

4X4 inputs 5X5 outputs

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

13

Proposed UWB Camera

Antenna LNA

13

Proposed UWB Camera

Antenna LNA

13

Proposed UWB Camera

Antenna LNA

Transconductance Amplifier

13

Proposed UWB Camera

Antenna LNA Unit Delay Cell ( τ )

Transconductance Amplifier Delay Line Termination

13

Proposed UWB Camera

Antenna LNA Unit Delay Cell ( τ )

Transconductance Amplifier Detector Driver (RF Buffer)

Delay Line Termination

13

Proposed UWB Camera

Antenna LNA Unit Delay Cell ( τ )

Transconductance Amplifier Detector Driver (RF Buffer) Detector Array (7X7 Pixels)

Delay Line Termination

13

Proposed UWB Camera

Electromagnetic Beams (7X7 Directions) Antenna LNA Unit Delay Cell ( τ )

Transconductance Amplifier Detector Driver (RF Buffer) Detector Array (7X7 Pixels)

Delay Line Termination

14

Signal Flow for Pixel 44

X-direction

Y-direction

Delay In11 Æ Out44 = 4τ + 4τ = 8τ Delay In12 Æ Out44 = 4τ + 4τ = 8τ 4τ

RFin11

Delay In21 Æ Out44 = 4τ + 4τ = 8τ Delay In22 Æ Out44 = 4τ + 4τ = 8τ

4τ Z

RFin12

RFin21

X

4τ

RFin22 4τ

Y

15

Signal Flow for Pixel 52

X-direction

Y-direction

Delay In11 Æ Out52 = 5τ + 2τ = 7τ Delay In12 Æ Out52 = 5τ + 6τ = 11τ 5τ

RFin11

Delay In21 Æ Out52 = 3τ + 2τ = 5τ Delay In22 Æ Out52 = 3τ + 6τ = 9τ

3τ Z

RFin12

RFin21

X

2τ RFin22 6τ

Y

16

UWB Camera Block Diagram RFin12

RFin11 LNA

Bias Circuit

VGA Transconductance Amplifier

Detector Driver (RF Buffer) Energy Detector

Digital Controller

RFin21

RFin22

17

Embedded Equalizer Optimal-Embedded Equalizer

Original-Embedded Equalizer

Gain

Gain Frequency

Array Gain

Frequency

Frequency

Group Delay

Group Delay

Group Delay

Frequency

Group Delay

Gain

Gain Frequency

Frequency

Array Gain

Array Gain

Array Gain

Frequency

Frequency

Embedded equalizer maintains the same array gain for all directions.

18

UWB Front-end Design Vdd

Mf

Lsp

Pad

50Ω

M1 M2

Delay Line

Ls Vb2

Lg Vb1 Pad Vin+

Vb3

Vb4

Vin-

UWB LNA

3-Stage UWB VGA

-3dB bandwidth Power gain |S11| (1GHz-15GHz) Noise figure 1 dB Compression Point (input power) Current Consumption

17GHz 19dB