A signal amplification circuit comprises a low pass filter circuit (100). The low pass filter circuit (100) comprises two input ends and two output ends and further comprises two capacitors (C1, C2) having opposite polarities respectively connected between two output ends. A buffer circuit (200) comprises two input ends, a first operational amplifier (A1) and a second operational amplifier (A2), two output ends and a plurality of switches. A switched capacitor integrated circuit (300) comprises two input ends, a third operational amplifier (A3), a plurality of capacitor modules, a plurality of chopper modulators and two output ends. A signal switch (S) is used to control the on and off states of voltage signal before amplification.