Silicon field emitter arrays (FEAs) -based cold cathodes have shown promise in many applications under harsh environments such as x-ray sources and high-power microwave devices due to the temperature independence of tunneling current and the property of ballistic transport [ 1 – 3 ] . We report an unexpected, yet reproducible Negative Differential Resistance (NDR) region within the device output characteristics of gated FEAs. These results were obtained by utilizing an on-chip flat silicon anode with etched stand-offs to define the anode-to-emitter distances of <100μm. Our analysis using calculations and simulation reveal that the parallel-plate configuration introduces a deceleration of electrons in the channel between the anode and gate when the anode voltage, V AE , is lower than the gate voltage, V GE .