BRIDGE SENSOR WITH COLLOCATED ELECTRONICS AND TWO-WIRE INTERFACE

• US 20100244813A1
• Filed: 03/30/2009
• Published: 09/30/2010
• Est. Priority Date: 03/30/2009
• Status: Active Grant

• Current Assignee: PCB Piezotronics, Inc. (Amphenol Corporation)
• Original Assignee: PCB Piezotronics, Inc. (Amphenol Corporation)
• Inventors: Higbee, James R., Hynd, John William, Sill, Robert D.
• Granted Patent: US 8,179,121 B2
• Time in Patent Office: Days
• US Class Current: 324/101
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01R 17/10 AC or DC measuring bridges

Abstract

A transducer, including: a housing; a bridge sensor circuit disposed within the housing and including at least one micro electro-mechanical systems (MEMS) sensing elements and first and second output ports; circuitry disposed within the housing; and an input/output (I/O) line electrically connected to the circuitry, accessible at an exterior of the housing, and adapted for receipt of input voltage or current. The circuitry is for generating a single data signal that combines respective outputs of the first and second output ports, and transmitting the DC-coupled single data signal on the I/O line. The circuitry is for generating and transmitting to the bridge sensor circuit an excitation current or voltage using the input voltage or current.

Claims

1. A transducer, comprising:

a housing;

a bridge sensor circuit disposed within the housing and including at least one micro electro-mechanical systems (MEMS) sensing element and first and second pluralities of sensor input/output (I/O) ports;

a differential amplifier disposed within the housing and including first and second pluralities of amplifier I/O ports, wherein the first plurality of amplifier I/O ports is electrically connected to the first plurality of sensor I/O ports;

a conversion circuit disposed within the housing and including a plurality of conversion I/O ports and first and second conversion I/O ports, wherein the plurality of conversion I/O ports is electrically connected to the second plurality of amplifier I/O ports or the second plurality of sensor I/O ports; and

,

first and second transducer I/O lines, accessible at an exterior of the housing, and electrically connected to the first and second conversion I/O ports, respectively.

2. The transducer of claim 1 wherein the conversion circuit is for providing power and a ground on at least some of the conversion I/O ports from the plurality of conversion I/O ports.

3. The transducer of claim 2 wherein the second plurality of sensor I/O ports includes first and second sensor I/O ports and wherein the conversion circuit is for providing power to the first sensor I/O port and ground to the second sensor I/O port.

4. The transducer of claim 2 wherein the second plurality of amplifier I/O ports includes first and second amplifier I/O ports and wherein the conversion circuit is for providing power to the first amplifier I/O port and ground to the second amplifier I/O port.

5. The transducer of claim 1 wherein the first transducer I/O line is adapted for connection to a current source and wherein the conversion circuit is for generating an excitation voltage using current on the first transducer I/O line from the current source.

6. The transducer of claim 5 wherein the conversion circuit is for providing the excitation voltage on at least some conversion I/O ports from the plurality of conversion I/O ports.

7. The transducer of claim 1 wherein the first transducer I/O line is adapted for connection to a current source, wherein the conversion circuit includes a third conversion I/O port and the second plurality of sensor I/O ports includes a first sensor I/O port electrically connected to the third conversion I/O port, and wherein the conversion circuit is for supplying an excitation current, using current from the current source, at the third conversion I/O port.

8. The transducer of claim 7 wherein the conversion circuit is for generating an operating voltage using current on the first transducer I/O line from the constant current source and wherein the conversion circuit is for providing the operating voltage on at least some of the conversion I/O ports from the plurality of conversion I/O ports electrically connected to the second plurality of amplifier I/O ports.

9. The transducer of claim 1 wherein the first plurality of sensor I/O ports includes first and second sensor I/O ports, wherein the first plurality of amplifier I/O ports include first and second amplifier I/O ports electrically connected to the first and second sensor I/O ports;

wherein the bridge sensor circuit is for generating respective electrical signals on the first and second sensor I/O ports;

wherein the second plurality of amplifier I/O ports includes a third amplifier I/O port;

wherein the amplifier circuit is for generating and providing on the third amplifier I/O port an amplifier signal combining the respective electrical signals on the first and second sensor I/O ports;

wherein the plurality of conversion I/O ports includes a third conversion I/O port electrically connected to the third amplifier I/O port; and

wherein the conversion circuit is for generating and providing at the first conversion I/O port a conversion signal representative of the amplifier signal.

10. The transducer of claim 1 wherein the sensor circuit includes a Wheatstone bridge circuit with four resistor and wherein the at least one MEMS sensing element includes the four resistors.

11. The transducer of claim 1 wherein the conversion circuit includes a third conversion I/O port and the second plurality of amplifier I/O ports includes a first amplifier I/O port, and the transducer further comprising a filter circuit, disposed in the housing and including:

a first filter I/O port electrically connected to the first amplifier I/O port;

a second filter I/O port electrically connected to the third conversion I/O port; and

,

a plurality of filter I/O ports electrically connected to the plurality of conversion I/O ports.

12. The transducer of claim 11 wherein the conversion circuit is for providing power and a ground on at least some of the conversion I/O ports from the plurality of conversion I/O ports connected to the plurality of filter I/O ports.

13. The transducer of claim 11 wherein the first plurality of sensor I/O ports includes first and second sensor I/O ports, wherein the first plurality of amplifier I/O ports include first and second amplifier I/O ports electrically connected to the first and second sensor I/O ports;

wherein the bridge sensor circuit is for generating respective electrical signals on the first and second sensor I/O ports;

wherein the amplifier circuit is for generating and providing on the first amplifier I/O port an amplifier signal combining the respective electrical signals on the first and second sensor I/O ports;

wherein the filter circuit is for electrically filtering the amplifier signal and supplying the filtered amplifier signal at the second filter I/O port; and

wherein the conversion circuit is for generating and providing at the first conversion I/O port a conversion signal representative of the filtered amplifier signal.

14. The transducer of claim 1 wherein the conversion circuit is for transmitting excitation power to the first plurality of sensor I/O ports, wherein the differential amplifier is for receiving respective electrical signals, including a DC component, from the second plurality of sensor I/O ports, and wherein the conversion circuit is for providing, on the first or second transducer I/O line, a conversion signal including the DC component.

15. A signal converter, comprising:

a housing;

a first plurality of converter input/output (I/O) lines accessible at an exterior of the housing and adapted for connection to a plurality of sensor I/O lines for a bridge sensor transducer, the bridge sensor transducer including at least one micro electro-mechanical systems (MEMS) sensing element;

a second plurality of converter I/O lines accessible at the exterior of the housing;

a differential amplifier disposed within the housing and including first and second pluralities of amplifier I/O ports, wherein at least some of the amplifier I/O ports from the first plurality of amplifier I/O ports are connected to at least some of the converter I/O lines from the first plurality of converter I/O lines; and

,

a conversion circuit disposed within the housing and including a plurality of conversion I/O ports and first and second conversion I/O ports, wherein at least at least some of the conversion I/O ports from the plurality of conversion I/O ports are electrically connected to at least some of the amplifier I/O ports from the second plurality of amplifier I/O ports and to at least some of the converter I/O lines from the first plurality of converter I/O lines and wherein the first and second conversion I/O ports are electrically connected to the second plurality of converter I/O lines.

16. The converter of claim 15 wherein the conversion circuit is for providing power and a ground on at least some of the first plurality of conversion I/O ports.

17. The converter of claim 16 wherein the first plurality of converter I/O lines includes first and second converter I/O lines and wherein the conversion circuit is for providing power to the first converter I/O line and ground to the second converter I/O line.

18. The converter of claim 16 wherein the second plurality of amplifier I/O ports includes first and second amplifier I/O ports and wherein the conversion circuit is for providing power to the first amplifier I/O port and ground to the second amplifier I/O port.

19. The converter of claim 15 wherein a first converter I/O line from the second plurality of converter I/O lines is adapted for connection to a current source and wherein the conversion circuit is for generating an excitation voltage using current on the first converter I/O line from the constant current source.

20. The converter of claim 19 wherein the conversion circuit is for providing the excitation voltage on at least some conversion I/O ports from the first plurality of conversion I/O ports.

21. The converter of claim 15 wherein a converter I/O line from the second plurality of converter I/O lines is adapted for connection to a current source and wherein the conversion circuit is for supplying an excitation current, using current from the current source, to at least one conversion I/O port, from the plurality of conversion I/O ports, electrically connected to the first plurality of converter I/O lines.

22. The converter of claim 21 wherein the conversion circuit is for generating an operating voltage using current on the converter I/O line from the current source and wherein the conversion circuit is for providing the operating voltage on at least one conversion I/O port, from the plurality of conversion I/O ports, electrically connected to at least one amplifier I/O port from the second plurality of amplifier I/O ports.

23. The converter of claim 15 wherein the first plurality of converter I/O lines includes first and second converter I/O lines arranged to receive respective electrical signals generated by the bridge sensor transducer, wherein the first plurality of amplifier I/O ports include first and second amplifier I/O ports electrically connected to the first and second converter I/O lines, respectively;

wherein the second plurality of amplifier I/O ports includes a third amplifier I/O port;

wherein the amplifier circuit is for generating and providing on the third amplifier I/O port an amplifier signal combining the respective electrical signals on the first and second converter I/O lines;

wherein the plurality of conversion I/O ports includes a third conversion I/O port electrically connected to the third amplifier I/O port; and

wherein the conversion circuit is for generating and providing at the first conversion I/O port a conversion signal representative of the amplifier signal.

24. The converter of claim 15 wherein the first plurality of converter input/output (I/O) lines is adapted for connection to a plurality of sensor I/O lines for a bridge sensor transducer including a Wheatstone bridge circuit with four MEMS sensing elements.

25. The converter of claim 15 wherein the conversion circuit includes a third conversion I/O port and the second plurality of amplifier I/O ports includes a first amplifier I/O port, and the converter further comprising a filter circuit, disposed in the housing and including:

a first filter I/O port electrically connected to the first amplifier I/O port;

a second filter I/O port electrically connected to the third conversion I/O port; and

,

a plurality of filter I/O ports electrically connected to the plurality of conversion I/O ports.

26. The converter of claim 25 wherein the conversion circuit is for providing power and a ground on at least some of the conversion I/O ports from the plurality of conversion I/O ports connected to the plurality of filter I/O ports.

27. The converter of claim 25 wherein the first plurality of converter I/O lines includes first and second converter I/O lines arranged to receive respective electrical signals generated by the bridge sensor transducer, wherein the first plurality of amplifier I/O ports include first and second amplifier I/O ports electrically connected to the first and second converter I/O lines, respectively;

wherein the amplifier circuit is for generating and providing on the first amplifier I/O port an amplifier signal combining the respective electrical signals on the first and second converter I/O lines;

wherein the filter circuit is for electrically filtering the amplifier signal and supplying the filtered amplifier signal at the second filter I/O port; and

wherein the conversion circuit is for generating and providing at the first conversion I/O port a conversion signal representative of the filtered amplifier signal wherein the conversion circuit is for generating and providing at the first conversion I/O port a conversion signal representative of the amplifier signal.

28. The converter of claim 15 wherein the conversion circuit is for providing excitation power on the at least some of the conversion I/O ports from the plurality of conversion I/O ports electrically connected to the at least some of the converter I/O lines from the first plurality of converter I/O lines, wherein the differential amplifier is for receiving respective electrical signals, including a DC component, on the at least some of the amplifier I/O ports from the first plurality of amplifier I/O ports connected to the at least some of the converter I/O lines from the first plurality of converter I/O lines, and wherein the conversion circuit is for providing, on the second plurality of converter I/O lines, a conversion signal including the DC component.

29. A transducer, comprising:

a housing;

a bridge sensor circuit disposed within the housing and including at least one micro electro-mechanical systems (MEMS) sensing element and first and second output ports;

circuitry disposed within the housing; and

,

an input/output (I/O) line electrically connected to the circuitry, accessible at an exterior of the housing, and adapted for receipt of input voltage or current, wherein the circuitry is for generating a conversion signal that combines respective outputs of the first and second output ports of the bridge sensor circuit, and transmitting the conversion signal on the I/O line.

30. A signal converter, comprising:

a housing;

circuitry disposed within the housing;

a plurality of converter input/output (I/O) lines accessible at an exterior of the housing and adapted for connection to a plurality of sensor I/O lines for a bridge sensor transducer, wherein the bridge sensor transducer includes a bridge sensor circuit with at least one micro electro-mechanical systems (MEMS) sensing element and wherein a first portion of the plurality of converter I/O lines are adapted to receive respective output signals from the bridge sensor circuit; and

,

a converter I/O line accessible at the exterior of the housing and adapted for receipt of constant current power, wherein the circuitry is for providing excitation power on a second portion of the plurality of converter I/O lines, generating a conversion signal that combines the respective output signals of the bridge sensor circuit, and transmitting the conversion signal on the I/O line.

31. A transducer, comprising:

a housing;

a bridge sensor circuit disposed within the housing and including at least one micro electro-mechanical systems (MEMS) sensing element;

circuitry disposed within the housing; and

,

an input/output (I/O) line electrically connected to the circuitry, accessible at an exterior of the housing, and adapted for receipt of input voltage or current, wherein the circuitry is for receiving output from the bridge sensor circuit and generating a conversion signal from the output from the bridge sensor circuit and wherein the output from the bridge sensor circuit and the conversion signal each include a DC component.

32. A signal converter, comprising:

a housing;

circuitry disposed within the housing;

a plurality of converter input/output (I/O) lines accessible at an exterior of the housing and adapted for connection to a plurality of sensor I/O lines for a bridge sensor transducer, wherein the bridge sensor transducer includes a bridge sensor circuit with at least one micro electro-mechanical systems (MEMS) sensing element and wherein a first portion of the plurality of converter I/O lines is adapted to receive an output, including a DC component, from the bridge sensor circuit; and

,

a converter I/O line accessible at the exterior of the housing and adapted for receipt of constant current power, wherein the circuitry is for providing excitation power on a second portion of the plurality of converter I/O lines, generating a conversion signal, including the DC component, from the output from the bridge sensor circuit, and transmitting the conversion signal on the I/O line.

33. A method of generating a two-wire output for a bridge sensor transducer, comprising the steps of:

accepting a first constant current on a two-wire line accessible at the exterior of a housing for the transducer; and

,

within the housing for the transducer;

generating an operating voltage or a second constant current using the first constant current on the two-wire line;

supplying the operating voltage or the second constant current to a bridge sensor circuit, the bridge sensor circuit including at least one micro electro-mechanical systems (MEMS) sensing element;

outputting, from the bridge sensor circuit and responsive to the operating voltage or the second constant current, first and second bridge sensor output signals;

generating a data signal combining the first and second bridge sensor output signals; and

,

outputting, on the two-wire line, the data signal.

34. A method of operating on a sensor signal for a transducer, comprising:

accepting a first constant current on a two-wire line accessible at the exterior of a housing for a converter element;

generating, within the housing for the converter element, an operating voltage or a second constant current using the first constant current on the two-wire line;

supplying, on a plurality of converter input/output (I/O) lines accessible at the exterior of the housing, the operating voltage or the second constant current, wherein the plurality of converter I/O lines are adapted for electrical connection to respective I/O lines for a bridge sensor transducer, the bridge sensor including at least one micro electro-mechanical systems (MEMS) sensing element;

accepting, on first and second converter I/O lines accessible at the exterior of the housing and adapted for electrical connection to first and second I/O lines, respectively, for the transducer, first and second bridge sensor output signals, respectively, the first and second bridge sensor output signals generated responsive to the operating voltage or the second constant current; and

,

outputting, on the two-wire line, a data signal combining the first and second bridge sensor output signals.

35. A method of generating an output signal for a transducer, comprising:

receiving, on an input/output (I/O) line electrically connected to circuitry in a housing and accessible at an exterior of the housing, input voltage or current, wherein the circuitry is connected to a bridge sensor circuit disposed within the housing and including at least one micro electro-mechanical systems (MEMS) sensing element and first and second output ports;

generating, using the circuitry, a data signal that combines respective outputs of the first and second output ports of the bridge sensor circuit; and

,

transmitting the data signal on the I/O line.

36. A method of operating on a sensor signal for a transducer, comprising:

accepting constant current power on a converter input/output (I/O) line accessible at the exterior of a housing;

connecting a plurality of converter I/O lines accessible at the exterior of the housing with a plurality of sensor I/O lines for a bridge sensor transducer, the bridge sensor transducer including a bridge sensor circuit with at least one micro electro-mechanical systems (MEMS) sensing element;

providing, using circuitry disposed within the housing, excitation power for the bridge sensor circuit on the plurality of converter I/O lines;

receiving, on the plurality of converter I/O lines, respective outputs from the bridge sensor circuit;

generating, using the circuitry disposed within the housing, a data signal that combines the respective outputs from the bridge sensor circuit; and

,

transmitting the data signal on the converter I/O line.

37. A method of generating an output signal for a transducer, comprising:

receiving, on an input/output (I/O) line electrically connected to circuitry in a housing and accessible at an exterior of the housing, input voltage or current, wherein the circuitry is connected to a bridge sensor circuit disposed within the housing and including at least one micro electro-mechanical systems (MEMS) sensing element and first and second output ports;

generating, using the circuitry, a conversion signal, with a DC component, that combines respective outputs of the first and second output ports of the bridge sensor circuit; and

,

transmitting the conversion signal on the I/O line.

38. A method of operating on a sensor signal for a transducer, comprising:

accepting constant current power on a converter input/output (I/O) line accessible at the exterior of a housing;

connecting a plurality of converter I/O lines accessible at the exterior of the housing with a plurality of sensor I/O lines for a bridge sensor transducer, the bridge sensor transducer including at least one micro electro-mechanical systems (MEMS) sensing element;

providing, using circuitry disposed within the housing, excitation power for the bridge sensor circuit on a first portion of the plurality of converter I/O lines;

receiving, on a second portion of the plurality of converter I/O lines, respective outputs, with a DC component, from the bridge sensor circuit;

generating, using the circuitry disposed within the housing, a conversion signal, with the DC component, that combines the respective outputs from the bridge sensor circuit; and

,

transmitting the conversion signal on the converter I/O line.