Research On Radio Frequency Resonant Inductance Measurement System

Relying on the advantages of simple structure,high reliability,good linearity,non-contact,high output power,inductive sensors are widely used in aerospace,advanced manufacturing,precision measurement and other fields to achieve the measurement of physical parameters such as force,acceleration,strain,flow,torque and so on.With the development of modern science and technology,the demand for miniaturization and integration of inductive sensors has also been put forward.Due to the limitation of the existing integration technology,the inductance of the integrated inductor is generally small,usually on the order of n H,and the corresponding operating frequency is on the order of GHz,which makes the traditional inductance measurement system unsuitable.Therefore,research on inductance measurement systems that can work under radio frequency has important application value.On the basis of analyzing and studying the research status and development trend of inductive sensing technology at home and abroad,this paper focuses on the research of radio frequency resonance measurement methods and technologies suitable for small inductances,and builds a corresponding measurement experiment system,and conducts related experimental study.The following main research work has been completed:1.On the basis of studying the principles of traditional transformer bridge and resonant amplitude modulation circuit,a design scheme of resonant bridge circuit is proposed.This scheme has the characteristics of high sensitivity of the resonant amplitude modulation circuit,and also has the characteristics of good linearity of the transformer bridge.Both theoretical derivation and experimental results show that under the same conditions,the sensor output signal is enhanced,and the enhanced multiple is approximately equal to the quality factor of the inductor.2.In order to meet the application requirements of integrated inductors,an inductance measurement system based on a radio frequency resonant bridge was further studied.The design of the inductor and probe structure working in radio frequency,detuning state detection circuit,automatic tuning feedback control circuit,radio frequency signal peak detection circuit,low noise radio frequency signal conditioning circuit,etc.are designed.Finally,the design and construction of the RF resonance inductance measurement system is completed.3.A performance test experiment was performed on the built measurement system using a micro-displacement experimental platform.The results showed that the system had a sensitivity of 1.992 m V/μm,a resolution of 80 nm,a repeatability error of 155.6 nm,and a non-linearity within a displacement range of 0.5 mm.The error is 0.09%,and the hysteresis error is 0.08%,which verifies the feasibility of the measurement system.