High Frequency Capacitive behavior of field stop trench gate IGBTs operating in Short Circuit
A wide experimental characterization about the input capacitance of Field Stop Trench Gate IGBTs is presented. It was achieved thanks to a novel experimental set-up which allows us to measure the input capacitance in the active region where the device operate during the Short Circuit (SC). The experimental results have been interpreted with the help of FEM simulations which confirm that negative capacitance is correlated with the accumulation of holes at the interface between N- IGBT base and gate oxide.
A Study of the Influence of Technology on the Negative Gate Capacitance in 1.2kV IGBTs
Due to the widespread usage of 1.2kV IGBTs for low and medium voltage applications, for the first time, this paper investigates the influence of technology on the instability effect of negative gate capacitance (NGC) in IGBT technologies - NPT (non punch-through), PT (punch-through) and FS (field stop). Due to the high density of plasma during forward conduction the p-channel inversion layer formed at the gate oxide/N-drift interface, acts as a low resistance path for holes to flow to the emitter contact. This induces negative charge on the gate electrode and NGC is said to occur when dQG/dVG becomes negative. NGC can influence turn-on and short circuit performance of an IGBT due to accumulation of holes under the gate oxide at high anode voltages. This paper attempts to explain why the FS is the optimum IGBT technology in terms of NGC performance. Moreover, it is shown that the level of gate voltage overshoot can be correlated with N-drift potential under the gate oxide, due to hole- accumulation within the induced p-channel.
Direct conversion pulsed UWB transceiver architecture
Ultra-wideband (UWB) communication is an emerging wireless technology that promises high data rates over short distances and precise locationing. The large available bandwidth and the constraint of a maximum power spectral density drives a unique set of system challenges. This paper addresses these challenges using two UWB transceivers and a discrete prototype platform.