Patent ID: 9013241
Filing Date: 2015-04-21
Classification: G01G,G01H,G01N,H03B,H03L

Abstract:
1. An electronic circuit for measuring an oscillation frequency of a resonator, comprising a first feedback loop which is a phase-locked loop comprising the resonator, a controlled oscillator and a first phase comparator, said first feedback loop locking an output frequency of the controlled oscillator at a resonant frequency of the resonator, said electronic circuit further comprising: a second feedback loop comprising a controllable phase shifter, a second phase comparator receiving the output of the controlled oscillator and the output of the controllable phase shifter, and the second phase comparator supplying a control signal for the phase shifter acting in a direction tending to reduce to zero a phase shift between its inputs, means being provided for storing the obtained phase-shift control signal, a self-oscillation loop comprising the resonator and the controllable phase shifter and linking the output of the controllable phase shifter to the input of the resonator, and means for activating the first feedback loop and the second feedback loop and deactivating the self-oscillation loop, during a calibration phase, and for deactivating the first and the second feedback loops and activating the self-oscillation loop, during an operation phase, the control signal of the controllable phase shifter during the operation phase being the control signal stored at the end of the calibration phase.