A Novel Implementation Method of Low-power Current-to-frequency Converter Based on the Charge-balanced Principle for High-precision Inertial Navigation Systems

The navigation accuracy of inertial navigation system (INS) is extremely sensitive to temperature because of its inertial devices in inertial measurement unit (IMU). However, the heat generated by high power dissipation of traditional current acquisition of quartz flexure accelerometer will lead to drastic changes in the internal temperature of IMU, which in turn leads to the degradation of navigation accuracy. To address this issue, a low-pow current-to-frequency converter (CFC) method is designed in this paper. The proposed CFC is based on the charge-balanced principle. By lowering supply voltage and reference voltage of constant current source in the CFC circuit, the power dissipation can be saved by more than a half. Then, a scheme of hardware compensations to improve the temperature characteristics and symmetry is achieved for the low-power CFC circuit. Experiments and measurements demonstrate that the proposed CFC circuit maintains outstanding nonlinearity, asymmetry and temperature performances, compared with the traditional solutions, indicating that the low-power CFC will have wider engineering applications.