Frequency-Selective Limiters Utilizing Contiguous-Channel Double Multiplexer Topology

A frequency-selective limiter that uses a linear-phase, contiguous-channel double multiplexer topology and RF-power-dependent coupling structures is shown in this paper. Frequency-selective limiting is achieved without the use of magnetic materials, nonreciprocal components, or parametric circuits. An L-band prototype with six contiguous 50-MHz-bandwidth channels was fabricated. Under measured low-power excitation, the limiter has a flat, composite passband with a 300-MHz-bandwidth and 1.6-1.9 dB insertion loss. The measured group delay is 16 ± 0.7 ns across the passband and does not have peaks at channel crossover frequencies. Limiting by 11.4 dB to over 22 dB occurs independently in any channel that experiences high-power excitation without disturbing adjacent channel bands. The measured limiting threshold is tunable from 16 to 33 dBm and can be designed to be tunable over other power ranges easily.