Wireless telemetry electronic circuitry for measuring strain in high-temperature environments

• US 8,223,036 B2
• Filed: 08/15/2008
• Issued: 07/17/2012
• Est. Priority Date: 08/15/2008
• Status: Active Grant

• Current Assignee: Cree Fayetteville, Inc. (Wolfspeed, Inc.)
• Original Assignee: Siemens Energy Incorporated (Siemens AG), Arkansas Power Electronics International, Inc. (Wolfspeed, Inc.)
• Inventors: Mitchell, David J., Kulkarni, Anand A., Subramanian, Ramesh, Roesch, Edward R., Waits, Rod, Schupbach, Roberto, Fraley, John R., McPherson, Brice, Western, Bryon, Lostetter, Alexander B.
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): BAUER, SCOTT ALLEN
• Application Number:
  US12/192,324
• Publication Number:
  US 20100039290A1
• Time in Patent Office: 1,432 Days
• Field of Search: 340/870.07, 608/03, 330/289
• US Class Current: 340/870.07
• CPC Class Codes: G01D 3/036 on measuring arrangements themselves
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G01K 1/12 for preventing damage due to heat overloading
• CPC Class Codes: G01K 1/20 Compensating for effects of temperature changes other than those to be measured, e.g. changes in ambient temperature
• CPC Class Codes: G01K 2205/00 Application of thermometers in motors, e.g. of a vehicle
• CPC Class Codes: G01L 1/2281 for temperature variations
• CPC Class Codes: H03F 1/306 in junction-FET amplifiers H03F1/303, H03F1/305, H03F1/309 take precedence
• CPC Class Codes: H03F 2200/18 the bias of the gate of a FET being controlled by a control signal
• CPC Class Codes: H03F 2200/447 the amplifier being protected to temperature influence

Abstract

In a telemetry system for use in an engine, a circuit structure (34) affixed to a moving part (20) of the engine is disposed for amplifying information sensed about a condition of the part and transmitting the sensed information to a receiver external to the engine. The circuit structure is adapted for the high temperature environment of the engine and includes a differential amplifier (102, 111) having an input for receiving a signal from a sensor (101, 110) disposed on the part. A voltage controlled oscillator (104, 115) with an input coupled to the output of the amplifier produces an oscillatory signal having a frequency representative of the sensed condition. A buffer (105, 116) with an input coupled to the output of the oscillator buffers the oscillatory signal, which is then coupled to an antenna (26) for transmitting the information to the receiver.

Claims

1. In a telemetry system for use in an internal combustion engine, a circuit structure affixed to a moving part of said engine for amplifying information sensed about a condition of said moving part, said circuit structure being adapted for the high temperature environment of said engine and comprising:

a differential amplifier having an input for receiving a signal from a sensor disposed on said part, the signal being representative of the condition of said part; and

,

said differential amplifier comprising a transistor having a gate bias network with a first resistive element having a positive temperature coefficient of resistance coupled between a source of positive voltage and the gate terminal of said transistor and a second resistive element having a zero temperature coefficient of resistance coupled between said gate terminal of said transistor and ground potential, whereby as the temperature increases the bias voltage at the gate terminal of said transistor decreases;

further comprising a third resistive element having a positive temperature coefficient of resistance coupled between the drain terminal of said transistor and said source of positive potential, whereby as the temperature increases the gain of said amplifier remains the same.

2. The system as in claim 1 wherein said third resistive element comprises tantalum nitride.

3. The system as in Claim 1;

wherein said circuit structure is fabricated with JFET transistors, all of which are fabricated with high temperature metallization;

wherein said high temperature metallization comprises an adhesion layer of tungsten; and

wherein said high temperature metallization further comprises a diffusion barrier.

4. The system as in claim 1 wherein said sensor comprises a strain gauge and the sensed condition of said part is strain placed upon said part during operation of said engine.

5. The system as in claim 1 wherein said first resistive element comprises tantalum nitride.

6. The system as in claim 1 wherein said second resistive element comprises platinum.

7. In a telemetry system for use in an internal combustion engine, a circuit structure affixed to a moving part of said engine for amplifying information sensed about a condition of said moving part, said circuit structure being adapted for the high temperature environment of said engine and comprising:

a differential amplifier having an input for receiving a signal from a sensor disposed on said part, the signal being representative of the condition of said part; and

,

said differential amplifier comprising a transistor having a gate bias network with a first resistive element having a positive temperature coefficient of resistance coupled between a source of positive voltage and the gate terminal of said transistor and a second resistive element having a zero temperature coefficient of resistance coupled between said gate terminal of said transistor and ground potential, whereby as the temperature increases the bias voltage at the gate terminal of said transistor decreases;

further comprising structure for transmitting said sensed information to a receiver external to said engine, said structure comprising;

a voltage controlled oscillator having an input coupled to an output of said amplifier for producing an oscillatory signal having a frequency representative of the sensed condition of said part; and

,

a buffer having an input coupled to an output of said voltage controlled oscillator for buffering said oscillatory signal, and having an output coupled to an antenna for transmitting said sensed information to said receiver.

8. The system as in claim 7 wherein said voltage controlled oscillator comprises a Colpitts oscillator for setting a reference carrier frequency.

9. The system as in claim 8 wherein said Colpitts oscillator comprises a gallium nitride (GaN) LED diode coupled in a reverse bias configuration as a varactor.

10. The system as in claim 9 wherein said LED diode comprises indium gallium nitride (InGaN).

11. In a telemetry system for use in a combustion engine, a circuit structure affixed to a moving part of said engine and being disposed for amplifying information sensed about a condition of said moving part and transmitting said sensed information to a receiver external to said engine, said circuit structure being adapted for the high temperature environment of said engine and comprising:

a differential amplifier having an input for receiving a signal from a sensor disposed on said part that is representative of the condition of said part;

said differential amplifier comprising a transistor having a gate bias network with a first resistive element having a positive temperature coefficient of resistance coupled between a source of positive voltage and the gate terminal of said transistor and a second resistive element having a zero temperature coefficient of resistance coupled between said gate terminal of said transistor and ground potential, whereby as the temperature increases the bias voltage at the gate terminal of said transistor decreases;

a voltage controlled oscillator having an input coupled to an output of said amplifier for producing an oscillatory signal having a frequency representative of the sensed condition of said part; and

,

a buffer having an input coupled to an output of said voltage controlled oscillator for buffering said oscillatory signal, and having an output coupled to an antenna for transmitting said sensed information to said receiver.

12. The system as in claim 11 wherein said first resistive element comprises tantalum nitride and said second resistive element comprises platinum.

13. The system as in claim 11 wherein said voltage controlled oscillator comprises a Colpitts oscillator for setting a reference carrier frequency.

14. The system as in claim 13 wherein said Colpitts oscillator comprises an inductance coil in parallel with a pair of serially coupled capacitors at a circuit node.

15. The system as in claim 14 wherein said inductance coil comprises a coil of gold or silver wire formed directly on a printed circuit board supporting said circuit structure and an alumina-based potting material surrounding the coil of wire.

16. The system as in claim 14 wherein said Colpitts oscillator comprises a gallium nitride (GaN) LED diode coupled in a reverse bias configuration as a varactor and in parallel with one of said capacitors between said circuit node and ground potential.

17. The system as in claim 16 wherein said LED diode comprises indium gallium nitride (InGaN) or other LED material capable of operating at greater than 300°

C.