Millimeter wave imaging array

• US 20030122079A1
• Filed: 09/26/2002
• Published: 07/03/2003
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Matloubian, Mehran, Brewer, Peter D., Pobanz, Carl W.
• Granted Patent: US 6,828,556 B2
• Time in Patent Office: Days
• US Class Current: 250/336.1
• CPC Class Codes: H01L 27/14649 Infrared imagers

Abstract

A focal plane array for millimeter wave imaging comprising a three dimensional stack of antenna elements and radiometer microwave monolithic integrated circuits (MMICs) embedded in polymer dielectric layers built on top of a silicon substrate. Each radiometer MMIC and antenna element comprise a radiometer pixel. The silicon substrate contains integrated circuits to collect and process the signals from each radiometer pixel and generate a full-frame video signal. The array can be fabricated on a single silicon wafer or can be constructed from structures fabricated on multiple silicon wafers.

Claims

1. An apparatus for millimeter wave imaging comprising:

a substrate comprising a first plurality of integrated circuits;

one or more receptacle layers positioned on top of the substrate, each receptacle layer of the one or more receptacle layers comprising;

a second plurality of integrated circuits encapsulated in a polymer film,

a plurality of vertical interconnects; and

an antenna carrying layer comprising;

an antenna dielectric layer and

a plurality of antenna elements positioned on top of the antenna dielectric layer.

2. The apparatus according to claim 1 further comprising:

one or more first encapsulation layers, each encapsulation layer located above each receptacle layer of said one or more receptacle layers and at least one encapsulation layer of the one or more encapsulation layers comprising;

a dielectric layer and

a plurality of horizontal interconnects deposited on top of the dielectric layer, the plurality of horizontal interconnects connecting the vertical interconnects, the first plurality of integrated circuits, and the second plurality of integrated circuits.

3. The apparatus according to claim 1 further comprising:

a metal layer deposited beneath the antenna dielectric layer; and

a ground plane dielectric layer located beneath the metal layer.

4. The apparatus according to claim 1 wherein said plurality of antenna elements are arranged such that each antenna element in said plurality of antenna elements is separated from another antenna element in two perpendicular directions.

5. The apparatus according to claim 1 wherein each integrated circuit of the second plurality of integrated circuits comprises a radiometer having:

a radio frequency input connected to a single antenna element of said plurality of antenna elements;

a control input;

a power input; and

,

a video output;

and wherein each integrated circuit of the first plurality of integrated circuits comprises a radiometer processor having;

a control output connected to the control input of said radiometer;

a power output connected to the power input of said radiometer;

a video input connected to the video output of said radiometer;

a digital video output;

a direct current input; and

,

a clock input.

6. The apparatus according to claim 5 wherein the radiometer comprises:

a temperature reference;

a radio frequency switch having a first input connected to the radio frequency input, a second input connected to the temperature reference, and a switch output, the radio frequency switch connecting the first input or the second input to the switch output, and the radio frequency switch controlled by the control input;

a low noise amplifier having an amplifier input and an amplifier output, the amplifier input connected to the switch output; and

a power detector having a detector input and a detector output, the detector input connected to the amplifier output, and the detector output connected to the video output.

7. The apparatus according to claim 5 wherein the radiometer processor comprises:

a direct current voltage regulator providing regulated power to the power output;

a chopping signal generator with chopping output, the chopping output connected to the control output;

a synchronous video detector connected to the video input and to the chopping output and providing a detected video output;

an integrator connected to the detected video output and providing an integrated video output; and

an analog-to-digital converter connected to the integrated video output and providing the digital video output.

8. The apparatus according to claim 5 wherein said radiometer comprises a microwave monolithic integrated circuit.

9. The apparatus according to claim 8 wherein said microwave monolithic integrated circuit comprises a three dimensional multiple layer structure, the three dimensional multiple layer structure comprising:

an RF MEMS switch in a first layer, the RF MEMS switch having a first input connected to the radio frequency input, a second input connected to a temperature reference, and an RF switch output, said RF MEMS switch being controlled by said control input;

a low noise amplifier integrated circuit in a second layer, said low noise amplifier integrated circuit having an amplifier input and an amplifier output, said amplifier input being connected to said RF switch output; and

a power detector integrated circuit in a third layer, said power detector integrated circuit having a power detector input connected to said amplifier output and having a power detector output connected to said video output.

10. The apparatus according to claim 9 wherein said low noise amplifier integrated circuit comprises an HEMT built on an InP substrate.

11. The apparatus according to claim 9 wherein said power detector integrated circuit comprises a backward diode.

12. A millimeter wave focal plane array comprising:

one or more focal plane array structures comprising;

a semiconductor wafer;

a first plurality of integrated circuits formed within the semiconductor wafer;

one or more receptacle layers positioned on top of the semiconductor wafer, each receptacle layer comprising a second plurality of integrated circuits encapsulated in a polymer film; and

an antenna carrying layer positioned on top of the receptacle layer, the antenna carrying layer comprising;

an antenna dielectric layer and

a plurality of antenna elements positioned on top of the antenna dielectric layer.

13. The millimeter wave focal plane array according to claim 12 wherein at least one integrated circuit in the second plurality of integrated circuits comprises a radiometer and at least integrated circuit in the first plurality of integrated circuits comprises a radiometer processor connected to said radiometer.

14. The millimeter wave focal plane array according to claim 13 further comprising:

a video frame processor connected to every radiometer processor.

15. The millimeter wave focal plane array according to claim 13 wherein said radiometer comprises a three dimensional multiple layer structure, the three dimensional multiple layer structure comprising:

an RF MEMS switch in a first layer, the RF MEMS switch having a first input connected to one antenna element of the plurality of antenna elements, a second input connected to a temperature reference, and an RF switch output;

a low noise amplifier integrated circuit in a second layer, said low noise amplifier integrated circuit having an amplifier input and an amplifier output, said amplifier input being connected to said RF switch output; and

a power detector integrated circuit in a third layer, said power detector integrated circuit having a power detector input connected to said amplifier output and having a power detector output.

16. The millimeter wave focal plane array according to claim 15 wherein said low noise amplifier integrated circuit comprises an HEMT built on an InP substrate.

17. The millimeter wave focal plane array according to claim 15 wherein said power detector integrated circuit comprises a backward diode.

18. A millimeter wave imaging system for producing a display based on millimeter wave radiation received from a viewed scene, said system comprising:

a millimeter wave focal plane array producing full image video signal, said array comprising

a substrate containing a plurality of substrate integrated circuits;

one or more receptacle layers, each receptacle layer comprising a plurality of radiometer integrated circuits encapsulated in a polymer film; and

an antenna carrying layer having a plurality of antenna elements; and

a lens directing the viewed scene onto the millimeter wave focal plane array;

a processing unit receiving the full image video signal and producing a display video signal; and

a video display generating a visual display from the display video signal.

19. The millimeter wave imaging system according to claim 18 wherein said substrate comprises a single silicon wafer.

20. The millimeter wave imaging system according to claim 18 wherein said substrate comprises multiple silicon wafers.

21. The millimeter wave imaging system according to claim 18 wherein one substrate integrated circuit of said plurality of substrate integrated circuits comprises circuitry to generate a full frame video signal and each remaining substrate integrated circuits of plurality of substrate integrated circuits comprises a radiometer processor.

22. The millimeter wave imaging system according to claim 18 wherein each radiometer integrated circuit of said plurality of radiometer integrated circuits comprises a three dimensional multiple layer structure, the three dimensional multiple layer structure comprising:

an RF MEMS switch in a first layer, the RF MEMS switch having a first input connected to one antenna element of the plurality of antenna elements, a second input connected to a temperature reference, and an RF switch output;

a low noise amplifier integrated circuit in a second layer, said low noise amplifier integrated circuit having an amplifier input and an amplifier output, said amplifier input being connected to said RF switch output; and

a power detector integrated circuit in a third layer, said power detector integrated circuit having a power detector input connected to said amplifier output and having a power detector output.

23. The millimeter wave imaging system according to claim 18 wherein the system is contained within a single handheld enclosure.

24. The millimeter wave imaging system according to claim 18 wherein the lens is a zoom lens.

25. The millimeter wave imaging system according to claim 18 wherein the video display comprises a liquid crystal display.