Measurement of the supply-current and internal impedance of VLSIs in a wide frequency range

In order to simulate the emission of PCBs (printed circuit boards) it is necessary to describe the RF-(radio-frequency)-sources very exactly in a wide frequency range. Due to internal switching of VLSIs a lot of RF-noise can be seen on their supply-pins. These currents I(f) are dependent on the relationship between the impedance Z(f) of the supply-system of the VLSI and Z(f) into the supply-system of the PCB at the supply-pins of the VLSI. This paper describes an effective method to measure both Z(f) and I(f) of the VLSI and compares it to extraction of Z(f) from the VLSI's geometrical data