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Detector, physical quantity measuring device, and electronic apparatus

  • US 8,593,130 B2
  • Filed: 08/24/2010
  • Issued: 11/26/2013
  • Est. Priority Date: 09/11/2009
  • Status: Active Grant
First Claim
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1. A detector that detects a detection signal corresponding to a driving vibration, which excites a vibrator in an oscillation loop, and a physical quantity to be measured, the detector comprising:

  • an amplifying circuit that amplifies a signal corresponding to the driving vibration and the physical quantity;

    a synchronous detection circuit that detects the amplified signal of the amplifying circuit in synchronization with an oscillation signal in the oscillation loop;

    an impedance conversion circuit that converts an output impedance of the synchronous detection circuit;

    a first low pass filter to which an output signal of the impedance conversion circuit is supplied and which outputs a first detection signal; and

    a second low pass filter to which the output signal of the impedance conversion circuit is supplied and which outputs a second detection signal, whereineach of the first and second low pass filters is formed by a switched capacitor filter circuit,a gain of the first low pass filter is different from that of the second low pass filter, andeach of the first and second low pass filters includes;

    a first integrator formed by a switched capacitor circuit having a first operational amplifier;

    a second integrator which is formed by a switched capacitor circuit having a second operational amplifier and which is connected to an output end of the first integrator;

    a feedback capacitor circuit having a third feedback capacitor inserted between an output end of the second integrator and a virtual ground end of the first operational amplifier; and

    a fourth feedback capacitor connected in parallel to the feedback capacitor circuit,the first integrator includes;

    a first input capacitor circuit connected between an output end of the impedance conversion circuit and the virtual ground end of the first operational amplifier; and

    a first feedback capacitor connected between an output end of the first operational amplifier and the virtual ground end of the first operational amplifier, andthe first integrator inputs a voltage difference between the output end of the impedance conversion circuit and the virtual ground end of the first operational amplifier and some charges, which are stored by a plurality of capacitors of the first integrator, to the virtual ground end of the first operational amplifier through a switch, and changes an output potential of the first operational amplifier using the first feedback capacitor, andthe second integrator includes;

    a second input capacitor circuit connected between the output end of the first operational amplifier and a virtual ground end of the second operational amplifier; and

    a second feedback capacitor connected between an output end of the second operational amplifier and the virtual ground end of the second operational amplifier, andthe second integrator inputs a voltage difference between the output end of the first operational amplifier and the virtual around end of the second operational amplifier and some charges, which are stored by a plurality of capacitors of the second integrator, to the virtual ground end of the second operational amplifier through a switch, and changes an output potential of the second operational amplifier using the second feedback capacitor.

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