Negative group delay circuit with independently tunable center frequency and group delay

In this paper, a design of negative group delay circuit (NGDC) with independently tunable center frequency and group delay (GD) is presented. Since the proposed structure consists of a parallel RLC resonance circuit, it is possible to obtain a variable negative GD by using a variable resistor and an adjustment of center frequency of GD is possible due to a variable inductor. To get the pure variable resistor, the transmission line (TL) terminated with the PIN diode is used. Similarly, the variable inductor is realized by TL terminated with the varactor diode. To show the effectiveness of the proposed NGDC, it is designed at 2.14 GHz of WCDMA downlink band. The measured negative GD time is -2 ~ -20ns, and are able to change the center frequencies of negative GD in the range of 2.04 ~ 2.24 GHz.