On-chip pulse generators are required to provide electrical pulses with the accuracy and controllability needed for on-wafer characterization of emerging Non Volatile Memories. However, unavoidable process spreads and component non-idealities may lead to excessive variations in pulse parameters with respect to the target values. This paper presents an automatic trimming procedure which is capable to enhance the accuracy of key timing parameters of the generated electrical pulse such as duration time and fall time. The error in the generated pulse parameters was experimentally evaluated to be within±10%.