Reconfigurable Series Negative Capacitor Using Coupled Line Negative Group Delay Circuit and Varactor Diode

This paper presents a reconfigurable microwave non-Foster negative capacitor using low loss negative group delay circuit and varactor diode. The proposed circuit consists of series transmission line, shunt short-circuited resistor connected coupled lines, and varactor diode. The negative capacitor is reconfigured by changing bias voltage of varactor diode. For the experimental demonstration, the proposed reconfigurable negative capacitor is designed, simulated, and measured. The measurement results show that the negative capacitor can be reconfigured from −0.72 pF to −0.85 pF by changing bias voltage of 2.5 V to 18 V.