Time- and frequency-domain measurements for an active negative group delay circuit

Time- and frequency-domain measurements of an active negative-group-delay (NGD) circuit exhibiting gain and NGD at low frequencies are presented. The active design eliminates the problem of high loss, associated with the passive transmission line exhibiting both negative refractive index and NGD. A high-frequency, active NGD circuit topology with an operation frequency near 2.5 GHz, is also discussed.