Time interval trimmed differential capacitance sensor
First Claim
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1. :
- A detector drive circuit for operation of a differential capacitance transducer, the circuit comprising;
a pair of sense capacitors;
a pair of drive signal generators that are structured to apply respective substantially opposing polarity excitation drive signals to the respective sense capacitors; and
a null bias trim circuit coupled for individually controlling the respective drive signal generators.
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Abstract
An apparatus and method for operation of a differential capacitance transducer, including generating substantially opposing polarity excitation drive signals by operation of a pair of drive signal generators, applying the excitation drive signals to a pair of sense capacitors of a differential capacitance sensor, sensing a differential capacitance at a common junction between the pair of sense capacitors; and individually controlling the drive signal generators for trimming a null bias of the sense capacitor pair at the common junction.
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Citations
20 Claims
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1. :
- A detector drive circuit for operation of a differential capacitance transducer, the circuit comprising;
a pair of sense capacitors;
a pair of drive signal generators that are structured to apply respective substantially opposing polarity excitation drive signals to the respective sense capacitors; and
a null bias trim circuit coupled for individually controlling the respective drive signal generators. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- A detector drive circuit for operation of a differential capacitance transducer, the circuit comprising;
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10. :
- A detector drive circuit for operation of a differential capacitance transducer, the circuit comprising;
a high frequency system clock oscillator;
a differential capacitance sensor having first and second sense capacitors that are coupled to a common junction therebetween;
a drive circuit having first and second drive signal generators that are sourced as a division of the system clock oscillator and are structured to generate respective first and second substantially opposing polarity excitation drive signals, the first and second drive signal generators being coupled to apply the respective first and second excitation drive signals to the respective sense capacitors of the differential capacitance sensor;
first and second switches coupled for controlling the respective first and second drive signal generators;
a programmable null bias trim circuit coupled for individually controlling the first and second switches;
a transimpedence amplifier coupled to the common junction between the sense capacitors;
a synchronous demodulator coupled to the transimpedence amplifier; and
a filter buffer coupled to the synchronous demodulator. - View Dependent Claims (11, 12, 13, 14)
- A detector drive circuit for operation of a differential capacitance transducer, the circuit comprising;
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15. :
- A method for operation of a differential capacitance transducer, the method comprising;
generating first and second substantially opposing polarity excitation drive signals by operation of respective first and second drive signal generators;
applying the first and second excitation drive signals to respective first and second sense capacitors of a differential capacitance sensor;
sensing a differential capacitance at a common junction between the first and second sense capacitors; and
individually controlling the respective first and second drive signal generators for trimming a null bias of the first and second sense capacitors at the common junction. - View Dependent Claims (16, 17, 18, 19, 20)
- A method for operation of a differential capacitance transducer, the method comprising;
Specification