Design of Large Dynamic Range Automatic Gain Control Circuit for Electronic Article Surveillance System

This paper proposes a large dynamic range automatic gain control (AGC) circuit based on variable gain amplifier VCA810 to enhance the detection distance and decrease the false alarm rate in EAS system, which is composed of controllable amplification circuit, comparison circuit, detection circuit and voltage adjustment circuit. The simulation results indicate that the designed circuit can realize the dynamic gain range of 34.08dB when the input signal varies from 20mV to 1020mV in the frequency range of 7.7-8.7MHz. It can effectively improve the false alarm problem of complex electromagnetic environment and increase the detection distance.