Drive circuit and physical quantity measuring device
AssigneeSeiko Epson Corporation
InventorMasayuki Yamaguchi
Life of this patent
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Abstract
In order for keeping the amplitude of the excitation current of a vibrator constant irrespective not only of the temperature variation but also of the manufacturing variation and the variation in frequency, a comparison control circuit for controlling the amplitude of the drive signal for exciting the vibrator includes a comparative voltage supply circuit for supplying the comparative voltage, and the comparative voltage supply circuit generates the comparative voltage with a constant current source and a second resistor made of a material the same as a material of a first resistor included in a current-voltage conversion circuit.
Claims10
A drive circuit adapted to output a drive signal for exciting a vibrator, the drive circuit comprising:
- a current-voltage conversion circuit adapted to convert an input excitation current into a voltage;
- and
- a comparison control circuit adapted to compare a comparative voltage with a voltage based on an output voltage from the current-voltage conversion circuit to thereby control an amplitude of the drive signal, wherein
- the comparison control circuit includes a comparative voltage supply circuit adapted to supply the comparative voltage, and
- the comparative voltage supply circuit generates the comparative voltage with a constant current source and a second resistor made of a material the same as a material of a first resistor included in the current-voltage conversion circuit.
Dependencies are inferred from the claim text.