Chipless and wireless sensor circuit and sensor tag

• US 10,753,902 B2
• Filed: 10/01/2018
• Issued: 08/25/2020
• Est. Priority Date: 10/01/2018
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hekmatshoartabari, Bahman
• Primary Examiner(s): Ha, Nathan W
• Application Number:
  US16/148,590
• Publication Number:
  US 20200103371A1
• Time in Patent Office: 694 Days
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/1468 using chemical or electrochemical methods, e.g. by polarographic means A61B5/1486 takes precedence
• CPC Class Codes: A61B 5/4504 Bones A61B5/4547 takes precedence
• CPC Class Codes: A61B 5/4547 Evaluating teeth
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: G01N 27/4145 specially adapted for biomolecules, e.g. gate electrode with immobilised receptors
• CPC Class Codes: G01N 27/4148 Integrated circuits therefor, e.g. fabricated by CMOS processing CMOS processing per se H01L21/82
• CPC Class Codes: G06K 19/0672 with resonating marks
• CPC Class Codes: G06K 19/077 Constructional details, e.g. mounting of circuits in the carrier
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 7/10376 the interrogation device being adapted for being moveable
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: H03K 19/018514 with at least one differential stage H03K19/018528 and H03K19/018542 take precedence
• CPC Class Codes: H04W 4/185 by embedding added-value information into content, e.g. geo-tagging
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

A wireless sensor circuit and sensor tag in which the output is directly converted to a frequency response. The sensor circuit includes a buffer transistor having gate, source and drain terminals configured as a source-follower, a gate resistor connected to the gate terminal of the buffer transistor, a supply voltage connected to the drain terminal of the buffer transistor, and an active load element and a capacitive load element connected to the source terminal of the buffer transistor. An input signal having an input frequency is applied to the buffer transistor via the gate resistor and an output signal is generated at the source terminal of the buffer transistor. The output frequency represents a response of the sensor circuit.

Claims

1. A sensor circuit, comprising:

a buffer transistor configured as a source-follower, the buffer transistor having gate, source and drain terminals;

a gate resistor connected to the gate terminal of the buffer transistor;

a supply voltage connected to the drain terminal of the buffer transistor;

an active load element comprising a transistor having a drain terminal connected to the source terminal of the buffer transistor, a control gate terminal connected to ground, a source terminal connected to ground and a sense gate terminal;

a capacitive load element connected between the source terminal of the buffer transistor and ground;

an input signal having an input frequency applied to the buffer transistor via the gate resistor; and

an output signal generated at the source terminal of the buffer transistor, the output signal having an output frequency;

wherein the output frequency represents a response of the sensor circuit.

2. The sensor circuit of claim 1, wherein the gate resistor is a variable resistor in which the resistance of the gate resistor is a function of a parameter being measured by the sensor circuit.

3. The sensor circuit of claim 1, wherein the resistance of the active load or the current sourced by the active load is a function of a parameter being measured by the sensor circuit.

4. The sensor circuit of claim 1, wherein the active load element is a normally-on field-effect transistor.

5. The sensor circuit of claim 1, wherein the buffer transistor is biased in saturation.

6. The sensor circuit of claim 1, wherein the active load element is an ion-sensitive field-effect transistor (ISFET).

7. The sensor circuit of claim 6, wherein the active load element is a double-gate ISFET, with the sense gate configured to measure a parameter being measured by the sensor circuit.

8. A sensor circuit, comprising:

a buffer transistor configured as a source-follower, the buffer transistor having gate, source and drain terminals;

a gate resistor connected to the gate terminal of the buffer transistor;

a supply voltage connected to the drain terminal of the buffer transistor;

an active load element comprising a transistor having a drain terminal connected to the source terminal of the buffer transistor, a control gate terminal connected to the source terminal of the buffer transistor, a source terminal connected to ground and a sense gate terminal;

a capacitive load element connected between the source terminal of the buffer transistor and ground;

an input signal having an input frequency applied to the buffer transistor via the gate resistor; and

an output signal generated at the source terminal of the buffer transistor, the output signal having an output frequency;

wherein the output frequency represents a response of the sensor circuit.

9. The sensor circuit of claim 8, wherein the gate resistor is a variable resistor in which the resistance of the gate resistor is a function of a parameter being measured by the sensor circuit.

10. The sensor circuit of claim 8, wherein the resistance of the active load or the current sourced by the active load is a function of a parameter being measured by the sensor circuit.

11. The sensor circuit of claim 8, wherein the active load element is a normally-off field-effect transistor.

12. The sensor circuit of claim 8, wherein the buffer transistor is biased in saturation.

13. The sensor circuit of claim 8, wherein the active load element is an ion-sensitive field-effect transistor (ISFET).

14. The sensor circuit of claim 13, wherein the active load element is a double-gate ISFET, with the sense gate configured to measure a parameter being measured by the sensor circuit.