This paper investigates the design method, characterization, and innovative uncertainty analysis of bandpass (BP) type negative group delay (NGD) passive cell. The lumped passive topology under study consists of a resistor and a passive RLC-series network. The voltage transfer function (VTF) based circuit theory introducing the BP NGD specification analytical expressions is established in function of the R, L and C lumped component parameters. The BP NGD performance is evaluated by figure of merit (FOM) formula. To demonstrate the BP NGD function, the design method was applied to a proof-of-concept (POC) operating at 125-kHz RFID standard center frequency. The BP NGD theory is validated by both AC simulation and measurement of POC and discrete component-based circuit prototype. Experimental BP NGD results in good agreement with calculation and simulation are obtained with NGD value of -36.77 μs, 8% NGD bandwidth, and an attenuation lower than -9.6 dB. Innovative expressions of BP NGD parameter uncertainties are established versus the POC circuit parameters. The BP NGD specification variations are interpreted with respect to the influence of constituting component uncertainties via comparison between the established NGD uncertainty theory and co-simulated sensitivity analyses.