Introduction If used in combination with an exter- nal DC power supply, the Agilent 4155C/4156C semiconductor param- eter analyzer can easily evaluate the DC characteristics of a power device that requires a current of several amperes. This application note describes how to connect the highly cost-effective Agilent E3615A DC power supply to the 4155C and to use the Agilent 4155C’s automatic analysis functions to automatically calculate threshold voltage (Vth).