Oscillation type inertia force sensor

摘要

An oscillation type inertia force sensor includes an oscillator, an oscillation circuit unit, and a detection circuit unit. The oscillation circuit unit functions as a self oscillation circuit of a closed loop with the oscillator as a resonant element, and includes an AGC circuit. The AGC circuit includes a VGA circuit, a comparison circuit comparing a predetermined reference voltage with a voltage of the monitor signal to output a control signal based on the compared result, and a pulse width modulation circuit modulating the control signal to a pulse width modulation signal. Based on the pulse width modulation signal, the driving signal is modulated with the output of the VGA circuit switched between an ON state and OFF state to control the degree of the amplification factor of the VGA circuit.

主权项

1. An oscillation type inertia force sensor comprising:
an oscillator used to detect inertia force; an oscillation circuit unit that supplies a driving signal to the oscillator; and a detection circuit unit that detects inertia force of the oscillator; wherein the oscillation circuit unit is a self oscillation circuit of a closed loop with the oscillator defining a resonant element, and includes an automatic gain control circuit that amplifies a monitor signal according to an oscillating state of the oscillator to generate and supply to the oscillator the driving signal; the automatic gain control circuit includes:
an amplification circuit that amplifies the monitor signal;a comparison circuit that compares a predetermined reference voltage with a voltage of the monitor signal to output a control signal to control a degree of an amplification factor of the amplification circuit based on a compared result; anda pulse width modulation circuit that modulates the control signal output from the comparison circuit into a pulse width modulation signal having a frequency higher than a frequency of the monitor signal; whereinbased on the pulse width modulation signal modulated at the pulse width modulation circuit, the driving signal is modulated with an output of the amplification circuit switched between an ON state and an OFF state to control the degree of the amplification factor of the amplification circuit.