We propose and experimentally demonstrate a novel circuit based on graphene FETs (GFETs) showing excellent negative differential resistance (NDR) characteristics at room temperature. The proposed GNDR circuit exploits a closed loop connection of 1-GFET with a 2-GFET inverter, being highly scalable. The circuit is demonstrated using large-area chemical vapor deposition grown graphene and no doping step, which makes it compatible with silicon-based circuits. It exhibits improved peak-to-valley current ratio (PVCR), higher NDR level and wider voltage range over which NDR is valid, as compared to any previous graphene NDR. The NDR is uniquely tunable with the supply voltage as well as with back bias voltage. We show that PVCR of up to 2 can be achieved. In comparison to other NDR technologies, the graphene NDR has a high peak-current-density of the order of 1 mA/μm, which offers opportunities for designing circuits with high current drive. © 2015 IEEE.