Research on reducing noise of conditioning circuits of sensor

2019-10-21 13:55:39

noise profile surface circuits preamplifier

责任者: Zhang Shou-Yu;Yu Pu;Zhu Pei-Xia 单位: Shanghai Jiaotong Univ., China 来源出处: Chinese Journal of Scientific Instrument(Chin. J. Sci. Instrum. (China)),1998/04/,19(2):158-62 摘要: This paper reports the analyzing methods and specific steps for reducing the noise of conditioning circuits by studying conditioning circuits for high precision surface profile measurement. The circuits with self-designed surface profile sensor have succeeded in detecting micro-displacement of one nanometer. The noise model of preamplifier is analyzed and the conditioning circuits for surface profile sensors are designed. A synchronizing integrator is employed to construct a narrow-band detecting system with a synchronous demodulator based on the dynamical tracking filter rather than the general RC active bandpass filter. It is effective to restrain circuits noises and disturbances. In order to obtain low output noise of preamplifier, two methods are employed: one is to reduce the temperature noise of source resistor; another is to make the working frequency be as near as possible to the resonance frequency. FETs and amplifiers are combined to form the preamplifier. In order to get optimum noise matching between the sensor and the preamplifier, the input transformer matching method which is simple and practical is applied. The design of these circuits and principles for selecting parameters are analyzed in detail 关键词: circuit noise;demodulators;electric sensing devices;integrating circuits;preamplifiers;signal processing equipment;surface topography measurement;tracking filters;sensor conditioning circuits;noise reduction;surface profile measurement;high precision;self-designed surface profile sensor;noise model;preamplifier;synchronizing integrator;narrow-band detecting system;synchronous demodulator;dynamical tracking filter;low output noise;temperature noise;source resistor;resonance frequency;optimum noise matching;input transformer matching method