Investigation on the microwave pulse signal compression with NGD active circuit

Abstract—This paper demonstrates the exhibition of pulse compres-sion from an electronic circuit with negative group delay (NGD). This circuit consists of a field effect transistor (FET) cascaded with shunt RLC network. Theoretic and experimental investigations have proved that, at its resonance frequency, the group delay of this circuit is al-ways negative. The present study shows that around this resonance, it presents a gain form enabling to generate pulse compression. To validate this concept, as proof-of-principle, devices with one- and two-stages FET were implemented and tested. Measurements of the one-stage test device evidenced an NGD of about −2.5 ns and simulta-neously with 2 dB amplification operating at 622MHz resonance fre-quency. In the frequency domain, in the case of a Gaussian input pulse with 40MHz frequency standard deviation, this resulted in 125 % ex-pansion of pulse width compared to the input one. In time domain, simulations showed that the compression was about 80 % in the case of an input Gaussian pulse with 4 ns standard deviation. With the other prototype comprised of two-stage NGD cell, the use of a sine carrier of about 1.03GHz allowed to achieve 87 % pulse width compression. 1