Patent ID: 9088261
Filing Date: 2015-07-21
Classification: G01D,H03H

Abstract:
1. A circuit operable to capture the response of a resonant sensor to a target where the resonant sensor includes a resonator characterized by a resonant impedance loss factor, and a resonance state (resonator oscillation amplitude and resonator oscillation frequency), including a resonance state corresponding to steady-state oscillation, comprising: class D negative impedance circuitry configured to drive current into the resonator with a negative impedance, including loop control circuitry configured to generate the loop control signal based on a detected sensor resonance state, such that a time average of the drive current corresponds to a magnitude of the controlled negative impedance that substantially cancels the sensor resonator losses to maintain steady-state oscillation; thereby establishing a negative impedance control loop that includes the sensor resonator as a loop filter, and that controls negative impedance, such that the loop control signal corresponds to sensor response data that represents the response of the sensor to the target.