New-Tech Europe | March 2016 | Digital edition

Figure 5 Impedance measurement of the 2mΩ resistor, using Port 1 and Port 2, with and without the common mode coaxial transformer on the Keysight E5061B. The unique GP ports don’t require the transformer, but are limited to 30MHz

so the longer the cables the bigger the error. The result would be considered to be excellent even if the result were further from the nominal, in order to account for these additional tolerances. It is clear that the Picotest J2102A common mode transformer and a preamp are indispensable when it comes to getting the most accuracy during PDN measurement. Figure 5 A DC measurement is made using precision, low noise 6.5 Digit DMMs (Picotest M3500A) to obtain a second measurement for correlation. The power supply does not have current programming, which is the reason the current is set to an odd number. The two channels of the power supply are connected in parallel and both are in current limit for this measurement.

Figure 6 - Noise floor in Ohms on the Bode 100 using the J2102A and the J2180A preamplifier included

Figure 4, The Bode 100 measurement of the 250uOhm resistor shown in Figure 1. The measured resistance and ESL are shown

New-Tech Magazine Europe l 61