Optimal design on twin-T notch filter in electromagnetic exploration equipments

This paper analyzes the twin-T notch filter circuit, and gives the expressions of the transfer function, f₀, BW and Q. Based on calculation, analysis and simulation, the optimal resistances and capacitances are selected according to the characteristics of wide field electromagnetic signal and the suppression requirement of power frequency interference. Experiments show that the optimal design of twin-T notch filter not only keeps the required signal, but also filters out power frequency and its harmonic interference noise to the utmost.