Design of tunable negative group delay circuit for communication systems

In this paper, a design of tunable microstrip transmission line negative group delay circuit (NGDC) using p-i-n diodes is proposed. The design was based on reflective parallel R-L-C circuit and group delay (GD) can be varied with help of variable resistance. To get the variable resistance, the transmission line (TL) terminated with p-i-n diode is used. The GD is varied with help of bias voltages of p-i-n diodes. Both design equations and design procedures are presented. The measured GD time variation range is 0 ~ -20 ns and well agreed with simulation results.