Sensitivities in High-Bandwidth, High-Current Shunt Measurements for Silicon-Carbide Multi-Chip Power Modules

Emerging high-current Silicon Carbide (SiC) multi-chip power modules (MCPMs) are challenging traditional current measurement techniques used for device characterization. Coaxial shunts are typically employed for low-current device characterization measurements. However, these devices introduce non-negligible insertion inductance that is problematic when used for characterizing high-current MCPMs. Consequently, many researchers are adopting a “bar-style” shunt for high-current MCPM characterization. The bar-style shunt enables designers to maintain wide bussing throughout the characterization circuitry. However, one challenge with the bar-style shunt is its significantly lower resistance compared to a coaxial shunt, which reduces the signal-to-noise ratio (SNR). The poor SNR makes the bar-style shunt susceptible to environmental factors. One primary sensitivity that has been identified is the coaxial connection between the shunt and the oscilloscope. This manuscript evaluates the sensitivity of these connections and provides recommendations for performing high-fidelity current measurements using the bar-style shunt.