Signal Integrity Analysis of the Structure with Single Modal Reservation Before and After Failures

Abstract

To improve the reliability of radio electronic devices, engineers use redundancy of the most relevant circuits. The simplest and most common solution is classical cold redundancy in which the primary and redundant circuits are located far from each other. Meanwhile, locating the primary and redundant circuits close together makes it possible to use modal distortions to protect both circuits from unwanted ultra-wideband interference. This approach is known as modal redundancy or modal reservation (MR). This paper presents the results of signal integrity analysis for a structure with single MR before and after failures. It is shown that the bandwidth after failures changes. This affects the rate of data that can be excited to the input of the device without significant distortion of the useful signal. The authors used pseudorandom binary sequences with a data rate of 50 and 200 Mbps. It is experimentally shown that failures in the redundant circuit do not significantly degrade the quality of signal integrity in the bandwidth. Thus, the data-dependent jitter changes from 12 (before failures) to 19 ps (after the worst failure). In all investigated variants, the eye stays open; as a result, the bit error rate will be low. The mismatch of the redundant circuit has the largest effect on the noise amplitude. As a result, the signal-to-noise ratio decreases from 57 (before failures) to 28 (after the worst failure). To confirm the measurements, we performed electrodynamic simulations. Their results are in good agreement with the experimental data.