An Accurate Switching Current Measurement Based on Resistive Shunt Applied to Short Circuit GaN HEMT Characterization

Abstract

The use of a resistive shunt is one of the simplest and most used methods for measuring current in an electronic device. Many researchers use this method to measure drain current during short-circuiting of fast devices such as GaN HEMTs. However, the high switching speed of these devices together with the non-ideality of the shunt resistors produces an overestimation of the current in the initial phases of the transient. In this paper, a passive compensation network is proposed, which is formed by adding an inductor to the voltage measurement circuit and allows an accurate measurement of the current using the resistive shunt even in the presence of very fast devices. The proposed method is validated by simulations and experimental measurements.

High Frequency, High Efficiency, and High Power Density GaN-Based LLC Resonant Converter: State-of-the-Art and Perspectives

“…Moreover, many different studies on the short circuit characterization of GaN HEMTs have been performed in [153][154][155][156], showing the results of finite element simulations and experimental tests in different conditions. In [153], short circuit test on 650 V GaN HEMTs is conducted when the drain voltage is greater than 350 V. Simulation results showed that in these test conditions, a very high-power density was dissipated in a critical region of the device and it was intensified by significant current focalization, as proved by experimental observations.…”

“…Another relevant issue when working with GaN HEMTs is discussed in [156], where some problems related to the drain current measurement are shown. In particular, although the use of shunt resistors is one of the best ways to measure the current in very high frequency applications, it can distort the measurement because of the presence of parasitics.…”