Bridge sensor with collocated electronics and two-wire interface

• US 8,179,121 B2
• Filed: 03/30/2009
• Issued: 05/15/2012
• Est. Priority Date: 03/30/2009
• Status: Active Grant

• Current Assignee: PCB Piezotronics, Inc. (Amphenol Corporation)
• Original Assignee: PCB Piezotronics, Inc. (Amphenol Corporation)
• Inventors: Hynd, John William, Sill, Robert D., Higbee, James R.
• Primary Examiner(s): Phan, Huy Q
• Assistant Examiner(s): Allgood, Alesa
• Application Number:
  US12/413,995
• Publication Number:
  US 20100244813A1
• Time in Patent Office: 1,142 Days
• Field of Search: 324/123.R, 324/443, 324/207.19, 324/526, 324/610, 324/648, 324/651, 324/657, 324/666, 324/673, 324/680, 324/706, 324/101, 324/721, 324/725, 324/679, 737/08, 737/02
• US Class Current: 324/123.R
• 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 method of generating a two-wire output for a bridge sensor transducer, comprising the steps of:

accepting a first constant current from an internal electronic piezoelectric (IEPE) compatible two-wire current source on a two-wire line accessible at the exterior of a housing for the transducer; and

,

within the housing for the transducer;

converting said constant current to an excitation voltage or current using said constant current on said two-wire through a conversion circuit line;

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

outputting, from said bridge sensor circuit and responsive to said excitation voltage or current, first and second bridge sensor output signals;

generating through a conversion circuit a data signal combining said first and second bridge sensor output signals; and

,

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

2. The method of claim 1 wherein said data signal includes a DC component.

3. The method of claim 1 wherein said excitation voltage or current is thermally compensated.

4. A bridge sensor transducer for use with an internal electronic piezoelectric (IEPE) compatible two-wire circuit, comprising:

a resistive bridge sensor circuit having a plurality of bridge sensor input/output (I/O) ports;

a differential amplifier electrically connected to said resistive bridge sensor circuit, said differential amplifier configured to generate a differential amplifier output;

a conversion circuit electrically connected at least one of said bridge sensor I/O ports and electrically connected to said differential amplifier, said conversion circuit configured to convert a constant current supply from an IEPE compatible two-wire current source to an excitation voltage or current for input into said resistive bridge sensor circuit, and said conversion circuit further configured to convert said differential amplifier output to a single-ended DC-coupled output; and

two transducer I/O ports electrically connected to said conversion circuit, said transducer I/O ports configured and arranged for electrical connection to said IEPE compatible two-wire current source.

5. The bridge sensor transducer of claim 4 wherein said bridge sensor circuit, said differential amplifier and said conversion circuit are disposed within a single housing.

6. The bridge sensor transducer of claim 5 wherein said transducer I/O ports are accessible at the exterior of said housing.

7. The bridge sensor transducer of claim 4 wherein said bridge sensor circuit comprises a micro-electro-mechanical systems (MEMS) sensing element.

8. The bridge sensor transducer of claim 4 wherein said bridge sensor circuit comprises a plurality of strain gauges.

9. The bridge sensor transducer of claim 4 wherein said excitation voltage or current is thermally compensated.

10. The bridge sensor transducer of claim 4, further comprising a filter circuit electrically connected to said differential amplifier and electrically connected to said conversion circuit, said filter circuit configured and arranged to filter a signal from said differential amplifier.