Theoretical study on bandwidth enhancement of negative impedance converters with an emitter follower circuit

This paper proposes a new negative impedance converter (NIC) with an emitter follower (EF) circuit. Two types of NICs with EF and without EF, designed to generate a negative capacitance of -100 pF, are demonstrated theoretically by using circuit simulators. Compared with the NIC without EF, the proposed one can provide 1.7 times wider bandwidth from DC to 7.2 MHz with an amplitude deviation of less than 2.3 dB. The EF circuit is considered to be useful also for high-frequency-NICs to enhance their operational bandwidth.