Novel negative impedance converter with an emitter follower circuit for stable non-foster elements

For generation of non-Foster circuit elements with negative capacitance or negative inductance, this paper newly proposes a negative impedance converter (NIC) with an emitter follower circuit. The principle of the proposed circuit topology is introduced, and then, the negative capacitance with -100 pF is demonstrated by using bipolar transistors 2SC1815GR with h
_FE
of 283. The results indicate that (1) the voltage gain of the amplifier, A
_ν
, used in the NIC circuit should be 2 precisely, and (2) the emitter follower enhances the bandwidth of the non-Foster response. As an application, this paper shows that a negative group delay with the delay time from -1 ns to -2 ns and negligible insertion loss is generated in a wide frequency range.