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It has recently been shown that emerging frequency selective limiter (FSL) devices allow to suppress interference with high power levels in the same frequency band as desired signals. This paper introduces an FSL model for circuit simulations that was validated with measurement results of a prototype FSL device. An RF front-end was constructed with this FSL model and a transistor-level CMOS low-noise amplifier (LNA) design. A co-simulation methodology has been developed under large-signal interference considerations using the Bluetooth Low-Energy (BLE) standard as a representative example. Results from simulations with a two-tone signal confirm that the modeled FSL can provide a 9.4 dB reduction of the third-order intermodulation distortion (IMD3) components, which benefits resilience to interference. 

Abstract Optical frequency combs, featuring evenly spaced spectral lines, have been extensively studied and applied to metrology, signal processing, and sensing. Recently, frequency comb generation has been also extended to MHz frequencies by harnessing nonlinearities in microelectromechanical membranes. However, the generation of frequency combs at radio frequencies (RF) has been less explored, together with their potential application in wireless technologies. In this work, we demonstrate an RF system able to wirelessly and passively generate frequency combs. This circuit, which we name quasi-harmonic tag (qHT), offers a battery-free solution for far-field ranging of unmanned vehicles (UVs) in GPS-denied settings, and it enables a strong immunity to multipath interference, providing better accuracy than other RF approaches to far-field ranging. Here, we discuss the principle of operation, design, implementation, and performance of qHTs used to remotely measure the azimuthal distance of a UV flying in an uncontrolled electromagnetic environment. We show that qHTs can wirelessly generate frequency combs with μWatt-levels of incident power by leveraging the nonlinear interaction between an RF parametric oscillator and a high quality factor piezoelectric microacoustic resonator. Our technique for frequency comb generation opens new avenues for a wide range of RF applications beyond ranging, including timing, computing and sensing.