Diagnostic waveform generator for a sensor

1. A control circuit for an electrochemical sensor, the control circuit comprising:

power supply inputs configured to receive a supply voltage;

a first signal generator configured to receive control information and to generate a first waveform on a first output using the supply voltage and the control information;

a second signal generator configured to receive the control information and to provide a second waveform on a second output using the supply voltage and the control information; and

wherein an output voltage between the first output and the second output, in the diagnostic mode of operation of the control circuit, is a periodic waveform having a peak-to-peak voltage greater than the supply voltage.

2. The control circuit of claim 1 , including a controller configured to generate the control information.

3. The control circuit of claim 1 , wherein the first waveform includes a repeating pattern of a first voltage ramp and a second voltage ramp and the first signal generator is configured to generate the first voltage ramp and the second voltage ramp.

4. The control circuit of claim 1 , wherein the first signal generator is a first digital-to-analog converter (DAC).

5. The control circuit of claim 1 , wherein the second waveform includes a repeating pulse waveform; and

wherein the second voltage generator is configured to oscillate the second output between a first voltage and a second voltage to generate the repeating pulse waveform.

6. The control circuit of claim 1 , wherein the second signal generator is a second DAC.

7. The control circuit of claim 1 , including a dual output DAC, wherein the dual output DAC includes the first signal generator and the second signal generator.

8. The control circuit of claim 1 , wherein the supply voltage is less than or equal to 3.4 volts and the peak-to-peak voltage is greater than or equal to 3.5 volts.

9. The circuit of claim 1 , in combination with the electrochemical sensor.

10. A control circuit for an electrochemical sensor, the control circuit comprising:

power supply inputs configured to receive a supply voltage;

means for receiving control information;

means for applying a first waveform to a reference electrode of the electrochemical sensor during a diagnostic mode of operation using the supply voltage and the control information;

means for applying a second waveform to a diagnostic electrode of the electrochemical sensor during a diagnostic mode of operation using the supply voltage and the control information;

means for receiving sense information from the electrochemical sensor;

means for providing an indication of a material concentration using the sense information during a sense mode of operation; and

wherein, during the diagnostic mode of operation, a diagnostic waveform measured at the reference electrode and the diagnostic electrode includes a periodic signal having a peak-to-peak voltage greater than the supply voltage.

11. The control circuit of claim 10 , including means for switching a source of the sense information to the means for providing an indication of a material concentration between the sense mode of operation and the diagnostic mode of operation.

12. A system comprising:

a voltage supply configured to provide a supply voltage;

an electrochemical sensor; and

a control circuit configured to receive power from the voltage supply, the control circuit comprising:

means for generating a periodic, sensor diagnostic signal during a diagnostic mode of operation, wherein a peak-to-peak voltage of the periodic sensor diagnostic signal is greater than the supply voltage;

means for receiving a sense signal from a working electrode of the electrochemical sensor during a sensing mode of operation; and

means for providing an indication of a material concentration at an output of the control circuit using the sense signal.

13. The system of claim 12 , wherein the means for generating a periodic, sensor diagnostic signal includes:

a first signal generator configured to receive control information and to generate a first waveform on a first output using the supply voltage and the control information; and

a second signal generator configured to receive the control information and to provide a second waveform on a second output using the supply voltage and the control information.

14. The system of claim 12 , wherein voltage supply is a battery.

15. The control circuit of claim 12 , including a controller configured to generate the control information.

16. The control circuit of claim 12 , wherein the first waveform includes a repeating pattern of a first voltage ramp and a second voltage ramp and the first signal generator is configured to generate the first voltage ramp and the second voltage ramp.

17. The control circuit of claim 12 , wherein the first signal generator is a first digital-to-analog converter (DAC).

18. The control circuit of claim 12 , wherein the second waveform includes a repeating pulse waveform; and

wherein the second voltage generator is configured to oscillate the second output between a first voltage and a second voltage to generate the repeating pulse waveform.

19. The control circuit of claim 12 , wherein the second signal generator is a second DAC.

20. The control circuit of claim 12 , including a dual output DAC, wherein the dual output DAC includes the first signal generator and the second signal generator.