Chopper circuitry operable in a high temperature environment of a turbine engine
View Patent ↗Chopper circuitry may be adapted to operate in a high-temperature environment of a turbine. A first semiconductor switch ( 122 ) may have a first terminal coupled to receive a first output signal from a first leg ( 148 ) of a differential amplifier ( 150 ). A second switch ( 128 ) may have a first terminal coupled thru a first resistive element (R 1 ) to a second terminal of the first semiconductor switch. The first terminal of the second semiconductor switch may be coupled to receive thru a second resistive element (R 2 ) a second output signal from a second leg ( 152 ) of the amplifier. Switches ( 122,128 ) may be responsive to a switching control signal to respective gate terminals of the switches to supply an output signal, which alternates in correspondence with a frequency of the switching control signal from a first amplitude level to a second amplitude level, which effectively provides a doubling amplification factor.
1. A circuitry adapted to operate in a high temperature environment of a turbine engine, the circuitry comprising:
a sensing element disposed on a component of the turbine engine to sense a parameter of the component and provide a voltage differential indicative of the sensed parameter;
a differential amplifier having a first input terminal and a second input terminal respectively coupled to the sensing element to receive the voltage differential indicative of the sensed parameter; and
a chopper circuitry coupled to the differential amplifier and comprising:
a first semiconductor switch having a first terminal coupled to receive a first output signal from a first leg of the differential amplifier; and
a second semiconductor switch having a first terminal coupled by way of a first resistive element to a second terminal of the first semiconductor switch, the first terminal of the second semiconductor switch coupled to receive by way of a second resistive element a second output signal from a second leg of said differential amplifier, wherein the first and the second semiconductor switches are responsive to a switching control signal, the switching control signal being applied in parallel circuit to respective gate terminals of the first and the second semiconductor switches, wherein the second terminal of the first switch supplies an output signal comprising an alternating current (AC) signal, which alternates in correspondence with a frequency of the switching control signal from a first amplitude level corresponding to a level of the first output signal of said differential amplifier to a second amplitude level corresponding to a level of the second output signal of said differential amplifier, wherein a second terminal of the second semiconductor switch is electrically grounded.
2. The circuitry of claim 1 , wherein the respective first terminals of the first and the second semiconductor switches comprise respective drain terminals and the second terminals of the first and the second semiconductor switches comprise respective source terminals.
3. The circuitry of claim 1 , wherein the respective first terminals of the first and the second semiconductor switches comprise respective source terminals and the second terminals of the first and the second semiconductor switches comprise respective drain terminals.
4. The circuitry of claim 1 , wherein the first and the second semiconductor switches comprise respective junction gate field-effect transistor (JFET) switches.
5. The circuitry of claim 1 , wherein the first and the second semiconductor switches comprise a respective high-temperature, wide bandgap material.
6. The circuitry of claim 5 , wherein the high-temperature, wide bandgap material is selected from the group consisting of SiC, AIN, GaN, AIGaN, GaAs, GaP, InP, AIGaAs, AIGaP, AIInGaP, and GaAsAIN.
7. The circuitry of claim 1 , wherein the sensing element comprises a thermocouple to sense a temperature of the component, and the voltage differential is indicative of the sensed temperature of the component.
8. The circuitry of claim 7 , further comprising a periodic wave oscillator configured to generate the switching control signal, which comprises a periodic wave signal having a frequency indicative of a local temperature of the circuitry.
9. The circuitry of claim 8 , wherein a difference between the first amplitude level and the second amplitude level comprises a value approximately up to twice the voltage differential indicative of the sensed temperature of the component.
10. The circuitry of claim 1 , wherein the first and the second resistive elements comprise approximately equal resistance values.
11. A telemetry system comprising the circuitry of claim 1 .
12. A circuitry comprising:
a first semiconductor switch having a first terminal coupled to receive a first output signal from a first leg of a differential amplifier;
a second semiconductor switch having a first terminal coupled by way of a first resistive element to a second terminal of the first semiconductor switch, the first terminal of the second semiconductor switch coupled to receive by way of a second resistive element a second output signal from a second leg of said differential amplifier, wherein the first and the second semiconductor switches are responsive to a switching control signal, the switching control signal being applied in parallel circuit to respective gate terminals of the first and the second semiconductor switches, wherein the second terminal of the first switch supplies an output signal comprising an alternating current (AC) signal, which alternates in correspondence with a frequency of the switching control signal from a first amplitude level corresponding to a level of the first output signal of said differential amplifier to a second amplitude level corresponding to a level of the second output signal of said differential amplifier, wherein a second terminal of the second semiconductor switch is electrically grounded.
13. The circuitry of claim 12 , wherein the respective first terminals of the first and the second semiconductor switches comprise respective drain terminals and the second terminals of the first and the second semiconductor switches comprise respective source terminals.
14. The circuitry of claim 12 , wherein the respective first terminals of the first and the second semiconductor switches comprise respective source terminals and the second terminals of the first and the second semiconductor switches comprise respective drain terminals.
15. The circuitry of claim 12 , wherein the first and the second semiconductor switches comprise respective junction gate field-effect transistor (JFET) switches.
16. The circuitry of claim 12 , wherein the first and the second semiconductor switches comprise a respective high-temperature, wide bandgap material.
17. The circuitry of claim 16 , wherein the high-temperature, wide bandgap material is selected from the group consisting of SiC, AIN, GaN, AIGaN, GaAs, GaP, InP, AIGaAs, AIGaP, AIInGaP, and GaAsAIN.
18. The circuitry of claim 12 , further comprising a periodic wave oscillator configured to generate the switching control signal, which comprises a periodic wave signal having a frequency indicative of a local temperature of the circuitry.
19. The circuitry of claim 18 , further comprising a thermocouple electrically coupled to a first input terminal and to a second input terminal of said differential amplifier to supply a voltage differential indicative of a sensed temperature.
20. The circuitry of claim 19 , wherein a difference between the first amplitude level and the second amplitude comprises a value approximately up to twice the voltage differential indicative of the sensed temperature.
21. The circuitry of claim 12 , wherein the first and the second resistive elements have approximately equal resistance values.
22. The circuitry of claim 19 , adapted to operate in a high temperature environment of a turbine engine, the circuitry affixed to a rotatable component of the turbine engine to sense and configured to signal condition the voltage differential indicative of the sensed temperature of the rotatable component.