SELF-TUNING LOW-NOISE AMPLIFIER

A low-noise amplifier with a phase control loop is described in this paper. In the proposed circuit, the resonant frequency is auto-tuned to the input signal frequency. In that way, high gain (20 dB), a phase shift of -180o between input and output signals, and good selective characteristics are obtained. The amplifier is robust to parameter variations, ensuring maximal amplification of the input signal regardless of its frequency as long as it is within a specified frequency range (880-950 MHz). Hence, the proposed circuit possesses self-tuning properties. The stability of the phase loop is analyzed by using Lyapunov's control theory