Real-time digital compensation to reduce acceleration's sensitivity in quartz resonator

Abstract

The paper presents a digital compensator imposing real-time voltage to compensate the frequency offset of quartz resonator under acceleration. To begin with, a triple-axis MEMS acceleration sensor, whose package is less than 3 mm × 3 mm × 0.9 mm, is mounted at the bottom of quartz resonator. Then acceleration sensitivity vector, based on sensor's coordinator, can be calculated by imposing sinusoidal vibration on singular axis and measuring the amplitude of sideband. So, the frequency offset can be calculated and the compensate value can also be inferred. A digital circuit is designed to generate compensate voltage real time to counteract the frequency offset. A FPGA is employed, which can realize computation in one clock period. Experiments show that the digital compensator presented here has a good effect at low frequency vibration just at which mechanical cushion is ineffective. At steady state, it can almost eliminate the frequency offset. Because of the integration and miniaturization of digital elements, the whole compensator is flexible, low cost, and easy to be applied.