# US 2014/0151768 A1 · Terahertz imager with detection circuit

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- Number: US 2014/0151768 A1
- Document ID: US20140151768A1
- Status: Published application
- Kind: A1
- Application number: 13/692,716
- Filed: 2012-12-03
- Published: 2014-06-05
- Earliest claimed: 2012-12-03
- Assignees: STMicroelectronics S.r.l.
- Applicants: Stmicroelectronics S.A.
- Inventors: Ullrich Pfeiffer; Hani Sherry; Andreia Cathelin
- Web page: https://patentgrep.com/patent/US20140151768A1

## CPC

- H10F 39/8037: {the integrated elements comprising a transistor}
- G01S 7/352: {Receivers}
- G01S 13/887: {for detection of concealed objects, e.g. contraband or weapons}
- G01N 21/3581: using far infrared light; using Terahertz radiation
- G01V 8/005: {operating with millimetre waves, e.g. measuring the black losey radiation}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)

## Abstract

A pixel circuit including: a differential detection circuit having first and second transistors coupled in series between differential output nodes of an antenna, the antenna being configured to be sensitive to terahertz radiation, and wherein: a first main conducting node of the first transistor is coupled to a first of the differential output nodes of the antenna; and a first main conducting node of the second transistor is coupled to a second of said differential output nodes of the antenna, wherein second main conducting nodes of the first and second transistors are formed by a common semiconductor region.

## Claims

### Claim 1

A pixel circuit comprising:
a differential detection circuit having first and second transistors coupled in series between differential output nodes of an antenna, said antenna being configured to be sensitive to terahertz radiation, and wherein:
a first main conducting node of said first transistor is coupled to a first of said differential output nodes of said antenna; and
a first main conducting node of said second transistor is coupled to a second of said differential output nodes of said antenna, wherein second main conducting nodes of said first and second transistors are formed by a common semiconductor region (606).

### Claim 2 (depends on 1)

The pixel circuit of claim 1, wherein said first and second transistors have channels formed in a common well.

### Claim 3 (depends on 2)

The pixel circuit of claim 2, wherein said first and second transistors are each n-channel MOS transistors, and wherein said channels are formed in a common p-type well, and wherein said second main conducting nodes are source nodes formed by a common n-type region.

### Claim 4 (depends on 1)

The pixel circuit of claim 1, wherein an intermediate node between said first and second transistors is coupled to a capacitor of said pixel circuit.

### Claim 5 (depends on 4)

The pixel circuit of claim 4, wherein said antenna is a ring antenna comprising a biasing node equal distance from said differential output nodes of the antenna and configured to receive an antenna biasing voltage, and wherein said capacitor is coupled between said intermediate node and said antenna biasing voltage.

### Claim 6 (depends on 4)

The pixel circuit of claim 4, wherein said intermediate node is further coupled to a column line via a sense transistor.

### Claim 7 (depends on 1)

An image sensor comprising:
an array of pixel circuits each comprising the pixel circuit of claims 1; and
output circuitry adapted to perform analog to digital conversion of an output signal from each of said pixel circuits.

### Claim 8 (depends on 1)

An electronic device comprising:
a processor; and
an image sensor comprising an array of pixel circuits each comprising the pixel circuit of claim 1.

### Claim 9

A method comprising:
forming first and second transistors of a differential detection circuit of a pixel circuit of a terahertz image sensor including:
forming a first main conducting node of said first transistor;
forming a first main conducting node of said second transistor, wherein the first main conducting nodes of said first and second transistors are adapted to be coupled to differential nodes of an antenna; and
forming second main conducting nodes of said first and second transistors as a common semiconductor region.

### Claim 10 (depends on 9)

The method of claim 9, further comprising:
coupling said first main conducting nodes of said first and second transistors to differential output nodes of said antenna; and
coupling said common semiconductor region to a capacitor.