THE DESIGN OF TRANSFORMER BRIDGE ON CAPACITANCE DETECTION CIRCUIT OF ELECTROSTATIC LEVITATION ACCELEROMETER

Electrostatic levitation accelerometer（ELA），as a significant part of payload gravity satellite measurement，is used in measuring non-conservative forces.The high accuracy of the gravity field model has high resolution requirements for the accelerometer.The capacitance detection circuit is one of the cores of accelerometer.It is designed to detect very small change of differential displacement through very weak differential capacitance signal and the noise level directly affects the resolution of the accelerometer.The transformer bridge is designed to reduce the noise of circuit through analyzing the noise of the capacitance detection circuit.The results shows that when bridge resonances，there is the largest output impedance.The typical parameters are selected to carry out the simulation.When the resonance frequency of the bridge equals to the frequency of the capacitance detection signal，the output impedance reaches the largest.Therefore，the parameter should be selected when the resonance frequency of the bridge equals to the frequency of the capacitance detection signal to reduce the circuit noise greatly.