Design of low-noise and anti-saturation preamplifier for the transient electromagnetic receiver
WU Guo-qiang · Journal of Changchun Post and Telecommunication Institute · 2002
In TEM (Transient Electromagnetic Methods), in order to reduce the noise of preamplifier to improve the detection capability of receiver for weak signal in late period and eliminate the saturation for large signal in early period, the low-noise and anti-saturation preamplifier circuit for the Transient Electromagnetic receiver was designed. The low-noise preamplifier was made up by three ultra low noise precision high speed Op Amps name LT1028.Through the electromagnetism shielding and grounding, the interference and noise was reduced. The digitally controlled programmable-gain instrumentation amplifier named PGA202 provided different gains at different periods of transient signal to eliminate the saturation as well as keep the dynamic range of the TEM receiver. The preamplifier can also be used in other large dynamic range signal acquisition systems. The experiment result proved that the preamplifier improved the SNR(Signal-to-Noise Rate) and the capability of distinguishing the weak available signal from noise in late period of transient signal.