Terahertz imager

Patent metadata

Field	Value
Publication number	US-9726548-B2
Application number	US-201514925753-A
Country	US
Kind code	B2
Filing date	Oct 28, 2015
Priority date	Sep 12, 2012
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

A terahertz imager includes an array of pixel circuits. Each pixel circuit has an antenna and a detector. The detector is coupled to differential output terminals of the antenna. A frequency oscillator is configured to generate a frequency signal on an output line. The output line is coupled to an input terminal of the antenna of at least one of the pixel circuits.

First claim

What is claimed is:

1. A terahertz imager comprising:
an array of pixel circuits, each pixel circuit comprising
a differential output antenna comprising a first output terminal, a second output terminal, and an input terminal, and
a detector circuit comprising
a first transistor having a first conduction terminal coupled to the first output terminal, a second conduction terminal, and a control terminal coupled to a dedicated bias voltage input terminal,
a second transistor having a first conduction terminal coupled to the second output terminal, a second conduction terminal, and a control node coupled to the dedicated bias voltage input terminal,
a third transistor having a first conduction terminal coupled to a supply terminal, a second conduction terminal coupled to a first differential electrical output terminal, and a control terminal coupled to the second conduction terminal of the first transistor, and
a fourth transistor having a first conduction terminal coupled to the supply terminal, a second conduction terminal coupled to a second differential electrical output terminal, and a control terminal coupled to the second conduction terminal of the second transistor; and

a frequency oscillator configured to generate a frequency signal on an output line, the output line being coupled to the input terminal of the differential output antenna of at least one of the pixel circuits.

2. The terahertz imager of claim 1 , wherein the frequency oscillator comprises a ring oscillator having a plurality of inverters.

3. The terahertz imager of claim 1 , wherein:
the second conduction terminal of the first transistor is directly connected to the control terminal of the third transistor, and
the second conduction terminal of the second transistor is directly connected to the control terminal of the fourth transistor.

4. The terahertz imager of claim 1 , wherein:
the first conduction terminal of the first transistor is directly connected to the first output terminal, and
the first conduction terminal of the second transistor is directly connected to the second output terminal.

5. The terahertz imager of claim 1 , wherein:
the control terminal of the first transistor is directly connected to the dedicated bias voltage input terminal, and
the control terminal of the second transistor is directly connected to the dedicated bias voltage input terminal.

6. The terahertz imager of claim 1 , wherein the detector circuit further comprises a select transistor, the select transistor coupling the first conduction terminal of the third transistor and the first conduction terminal of the fourth transistor to the supply terminal, wherein a control terminal of the select transistor is coupled to a row selection terminal configured to receive a row selection signal.

7. The terahertz imager of claim 6 , wherein the detector circuit further comprises:
a first output transistor having a first conduction terminal coupled to the first differential electrical output terminal, a second conduction terminal coupled to a first column output terminal, and a control terminal coupled to a column selection terminal configured to receive a column selection signal,
a second output transistor having a first conduction terminal coupled to the second differential electrical output terminal, a second conduction terminal coupled to a second column output terminal, and a control terminal coupled to the column selection terminal,
a first current source having a first conduction terminal coupled to the first differential electrical output terminal and a second conduction terminal coupled to a reference terminal, and
a second current source having a first conduction terminal coupled to the second differential electrical output terminal and a second conduction terminal coupled to the reference terminal.

8. The terahertz imager of claim 1 , wherein the differential output antenna comprises an annular conductor, the first output terminal and the second output terminal being positioned at opposite points around the annular conductor and the input terminal being positioned at a point between the first output terminal and the second output terminal.

9. The terahertz imager of claim 8 , wherein the input terminal is positioned at a point of equal distance from the first output terminal and the second output terminal.

10. The terahertz imager of claim 9 , wherein the first output terminal and the second output terminal are positioned on an inner edge of the annular conductor and the input terminal is positioned on an outer edge of the annular conductor.

11. The terahertz imager of claim 1 , wherein the first transistor is an n-type transistor, the second transistor is an n-type transistor, the third transistor is a p-type transistor, and the fourth transistor is a p-type transistor.

12. A terahertz imager comprising:
an array of pixel circuits, each pixel circuit comprising
a differential output antenna comprising a first output terminal, a second output terminal, and an input terminal, and
a detector circuit comprising
a first transistor having a first conduction terminal coupled to the first output terminal, a second conduction terminal, and a control terminal coupled to a dedicated bias voltage input terminal,
a second transistor having a first conduction terminal coupled to the second output terminal, a second conduction terminal, and a control node coupled to the dedicated bias voltage input terminal, and
a third transistor having a first conduction terminal coupled to a supply terminal, a second conduction terminal coupled to an electrical output terminal, and a control terminal coupled to the second conduction terminal of the first transistor and coupled to the second conduction terminal of the second transistor, and
a capacitor coupled to the control terminal of the third transistor; and

a frequency oscillator configured to generate a frequency signal on an output line, the output line being coupled to the input terminal of the differential output antenna of at least one of the pixel circuits.

13. The terahertz imager of claim 12 , wherein:
the first conduction terminal of the first transistor is directly connected to the first output terminal,
the first conduction terminal of the second transistor is directly connected to the second output terminal,
the second conduction terminal of the first transistor is directly connected to the control terminal of the third transistor, and
the second conduction terminal of the second transistor is directly connected to the control terminal of the third transistor.

14. The terahertz imager of claim 12 , wherein:
the control terminal of the first transistor is directly connected to the dedicated bias voltage input terminal, and
the control terminal of the second transistor is directly connected to the dedicated bias voltage input terminal.

15. The terahertz imager of claim 12 , wherein the detector circuit further comprises:
a select transistor, the select transistor coupling the first conduction terminal of the third transistor to the supply terminal, wherein a control terminal of the select transistor is coupled to a row selection terminal configured to receive a row selection signal,
an output transistor having a first conduction terminal coupled to the electrical output terminal, a second conduction terminal coupled to a column output terminal, and a control terminal coupled to a column selection terminal configured to receive a column selection signal, and
a current source having a first conduction terminal coupled to the electrical output terminal and a second conduction termi

Assignees

• St Microelectronics Sa

Inventors

• Sherry Hani
• Cathelin Andreia
• Kaiser Andreas
• Pfeiffer Ullrich
• Grzyb Janusz
• Zhao Yan

Classifications

• G01N21/3581

  using far infrared light; using Terahertz radiation · CPC title

• G01J5/10 Primary

  using electric radiation detectors · CPC title

• G01J2005/202

  Arrays · CPC title

• Y10T29/49018

  with other electrical component · CPC title

• G01J5/20

  using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices · CPC title