Abstract

Due to the wide usage of very low frequency (VLF) wave for research on natural phenomena such as lightning, earthquake, and weather, a receiver for VLF application particularly with high-gain is absolutely required. This paper discusses about designing, realizing and characterizing a high gain radio frequency (RF) amplifier for VLF receiver application. The proposed amplifier which is designed using a junction field-effect transistor (JFET) of 2SK170 and an operational amplifier (OpAmp) of OP27 is intended to work at frequency range below 50kHz. After achieving the optimum design, the hardware realization is then carried out by deploying the designed amplifier on a printed circuit board. From the experimental characterization, it shows that the measured gain of realized amplifier at frequency of 19.8kHz satisfies with the design criteria and is 46.003dB with 1-dB compression point of -24dBm.

Keywords:RF amplifier; high-gain; JFET; OpAmp; very low frequency receiver