Vibrating gyro

A vibration gyro comprising:

• a piezoelectric vibration unit including a drive electrode and first and second electrodes, the piezoelectric vibration unit being arranged to vibrate in response to a drive voltage input into the drive electrode, and when deformed by a Coriolis force, to generate detection voltages at the first and second electrodes, the detection voltages being voltages having a potential difference corresponding to the deformation;
• an addition circuit arranged to add the detection voltages of the first and second electrodes;
• an automatic gain control circuit arranged to output the drive voltage while performing automatic gain control so that an output voltage of the addition circuit has a given amplitude;
• a balanced transformerless circuit arranged to output a voltage to the first and second detection electrodes via a detection resistance in a phase obtained by inverting an output voltage of the addition circuit, the voltage having an amplitude greater than amplitudes of the detection voltages;
• and
• a detection circuit arranged to detect the potential difference from the detection voltages of the first and second electrodes;
• wherein
• a circuit constant of the automatic gain control circuit is set so that
• V
• agc
• <
• V
• drv
• ′
• ×
• R
• k
• 2
• ×
• Z
• +
• R
• k
• ,
• where Vagc is the amplitude of each of the detection voltages, V′drv is a design upper limit value of the drive voltage, Rk is the detection resistance, which includes two parallel resistances, and Z is a drive resonant resistance of the piezoelectric vibration unit.