Pulsed pressure sensor circuit and method therefor

• US 5,351,549 A
• Filed: 10/01/1992
• Issued: 10/04/1994
• Est. Priority Date: 10/01/1992
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Baum, Jeffrey, Schultz, Warren J.
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): Oen, William L.
• Application Number:
  US07/954,996
• Time in Patent Office: 733 Days
• Field of Search: 73/708, 73/720, 73/721, 73/723, 73/726, 73/727, 73/754, 338/4, 364/558
• US Class Current: 73/723
• CPC Class Codes: G01L 9/06 of piezo-resistive devices

Abstract

A pulsed pressure sensor circuit (11) with increased sensitivity for measuring low pressures. A pulse generation circuit (12) is enabled by a microprocessor (28) to output a voltage pulse. The voltage pulse biases a pressure sensor (17) which has a port exposed to a pressure to be sensed. The pressure sensor (17) outputs a differential voltage which is proportional to the pressure at the port. The differential voltage is amplified by an amplifier (23) which has an output coupled to the microprocessor (28). A voltage divider circuit (26) is coupled to the pulse generation circuit (12) and has an output coupled to the microprocessor (28). The microprocessor (28) samples the voltages at the output of the amplifier (23) and the output of the voltage divider circuit (26). Microprocessor (28) then calculates the pressure using the sampled voltages and data stored in memory.

Claims

1. A pulsed pressure sensor circuit having increased sensitivity comprising:

a pressure sensor having a bias input, a port and an output, said pressure sensor for providing an output voltage corresponding to a pressure at said port when a bias voltage is applied to said bias input; and

a pulse generation circuit for providing a voltage pulse to said bias input of said pressure sensor, said voltage pulse biasing said pressure sensor for generating said output voltage.

2. The pulsed pressure sensor circuit of claim 1 wherein said pulse generation circuit has a control input responsive to an enabling signal applied thereto for providing said voltage pulse and wherein said pulse generation circuit provides a voltage pulse having a magnitude that exceeds a maximum DC bias voltage of said pressure sensor for increasing the sensitivity of the pulsed pressure sensor circuit.

3. The pulsed pressure sensor circuit of claim 2 further including:

an amplifier having an input coupled to said output of said pressure sensor and an output; and

a voltage divider circuit having an input coupled to said output of said pulse generation circuit and an output.

4. The pulsed pressure sensor circuit of claim 3 further including:

a microprocessor having a first input coupled to said output of said amplifier, a second input coupled to said output of said voltage divider circuit, a first output coupled to said control input of said pulse generation circuit, and a second output for providing a signal corresponding to a pressure sensed by said pressure sensor.

5. The pulsed pressure sensor circuit of claim 1 wherein said pulse generation circuit is responsive to said enabling signal from said microprocessor for varying the magnitude of said voltage pulse to change sensitivity of said pressure sensor.

6. A method for sensing pressure comprising:

exposing a port of a pressure sensor to a pressure;

biasing said pressure sensor with a voltage pulse; and

measuring an output voltage of said pressure sensor.

7. The method of claim 6 wherein said step of biasing said pressure sensor includes:

adjusting sensitivity of said pressure sensor by changing the voltage magnitude of said voltage pulse.

8. The method of claim 6 wherein said step of measuring an output voltage includes:

amplifying said output voltage of said pressure sensor;

sampling said amplified output voltage at a predetermined time; and

converting said voltage to a digital format.

9. The method of claim 8 further including:

sensing said voltage pulse;

reducing the magnitude of said voltage pulse;

sampling said reduced magnitude voltage pulse at a predetermined time; and

converting said sampled voltage pulse to a digital format.

16. A method as recited in claim 6 wherein said step of biasing said pressure sensor with a voltage pulse includes increasing a magnitude of said voltage pulse to increase sensitivity of said pressure sensor.

17. A method as recited in claim 6 wherein said step of biasing said pressure sensor with a voltage pulse includes reducing duty cycle of said voltage pulse to reduce average power dissipated by said pressure sensor.

10. A pulsed pressure sensing circuit comprising:

a pressure sensor having a bias input, a first output, a second output, and a port, said pressure sensor for providing an output voltage corresponding to a pressure at said port when a bias voltage is applied to said bias input;

a pulse generation circuit for providing a voltage pulse to said bias input of said pressure sensor, said voltage pulse biasing said pressure sensor for generating said output voltage wherein sensitivity of said pressure sensor is increased by increasing a magnitude of said voltage pulse and average power dissipated by said pressure sensor is reduced by said voltage pulse;

an amplifier for amplifying said output voltage of said pressure sensor having a first input and a second input coupled respectively to said first and second outputs of said pressure sensor and an output;

a voltage divider circuit having an input coupled to said output of said pulse generation circuit, and an output; and

means for calculating pressure having a first input coupled to said output of said amplifier, a second input coupled to said output of said voltage divider, a first output, and a second output coupled to said control input.

11. The pulsed pressure sensing circuit of claim 10 wherein said sensitivity of said pressure sensor increases as a magnitude of a voltage pulse of said pulse generation circuit is increased.

12. The pulsed pressure sensing circuit of claim 10 wherein said voltage divider circuit is a series connected resistor divider.

13. The pulsed pressure sensing circuit of claim 10 wherein said means for calculating pressure is a microprocessor.

14. The pulsed pressure sensing circuit of claim 13 wherein said microprocessor enables said pulse generation circuit to output a voltage pulse of a predetermined magnitude and duration and wherein said microprocessor samples said output of said amplifier and said output of said voltage divider circuit within said duration of said voltage pulse.

15. The pulsed pressure sensing circuit of claim 10 wherein said pressure sensor is a semiconductor pressure sensor.