Abstract:
The IP method is an important metal prospecting method.However,the IP signal is weak and easily interrupted by electromagnetic signals.Therefore,based on the OPA140 power amplifier chip,the input protection circuit,pre-amplifier,self-potential supplement circuit,low-pass filter,and the circuit transiting from ADC single-ended to double-ended are designed,realizing the development of low noise simulation front-end circuit,improving the ratio of signal and noise.Besides,a dynamic signal analyzer and spectrum analyzer are used to test the response of simulation front-end circuit noise and frequency.TINA-TI software platform simulates and calculates the equivalent input voltage noise of the pre-amplifier,and the test results are consistent with actual needs.The designed simulation front-end circuit is combined with the control panel to make a prototype,which is compared with ELREC 6 direct IP instrument.The results show the parallactic polarizability of the prototype,on the whole,goes with ELREC 6 IP instrument.The prototype can provide a high-quality signal for ADC.The development of low noise simulation front-end circuit meets the design requirements.