A novel design of 0.8 GHz – 1.2 GHz negative impedance series capacitor circuit

Abstract

Negative impedance converter (NIC) is a broadband matching technique in radio frequency (RF) based on the non‐Foster theory. This technique in conjunction with the effect of negative impedance has been proven to achieve a wider impedance matching bandwidth than other techniques. However, it still has problems in the areas of flexible connectivity, and mismatch in the real part of negative impedance and power consumption. Those problems have led to non‐Foster circuits (NFC) not being trusted as much as high unload Q module for broadband matching. In this paper, we propose a new idea for NFC that uses balun transformers to achieve negative reactance in 0.8 GHz to 1.2 GHz with the real part of the impedance is matched to 50 Ω when the imaginary part (normally, it is the reactance of negative impedance circuit) does not change. Finally, we show and compare our results with the ideal impedance of negative lump components in both the Smith Chart and reactance. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1801–1806, 2016

Novel design of a 2.1–2.9 GHz negative capacitance using a passive non-Foster circuit

“…The Bode-Fano criterion means that, to achieve broadband characteristics, the RF designer must sacrifice other parameters of the circuit including the large size, more loss and low Quality (Q). A reason for this problem was mentioned in our previous paper [2]: the reactance-versusfrequency slope of the negative capacitor is wider than that of the positive inductor in matching with a positive capacitor from 0.8-1.2 GHz. Therefore, when negative impedance is used in the matching network, the wideband could be easily achieved without increasing the size of circuits or loss parameter.…”

A design of passive negative shunt inductance circuit using negative group delay network

“…Non-Foster circuits (NFC) are circuits that relate to the negative impedance of negative lump elements, such as negative series capacitors or negative shunt inductors that can absorb a reactance of conventional lump elements [1]. By using the negative impedance of NFCs, one can be free from the gain-bandwidth limitation that results from the Bode-Fano criterion [2].…”