Nonlinear analysis and design of frequency selective limiters based on parametric circuits

A parametric circuit based on varactor-diodes is presented for its application as a frequency-selective limiter. A simplified analytical model is initially derived for a general understanding of the circuit performance. The power limitation is due to the frequency division of above threshold signals, leading to a reduction of the output power. Next harmonic-balance simulation is applied to analyze the limiter behavior in the presence of a strong and a weak signal. A matching technique is derived to increase the input-power range with high limitation level. Cascaded detuned stages are used to limit multiple above threshold signals. An in-depth analysis of the behavior under two interferers is also presented, showing that each stage enables the frequency division of a different interferer. The techniques have been successfully applied to a frequency selective limiter in the 850 MHz band.