Voltage Regulator Crosstalk

Voltage regulator crosstalk can cause serious problems in power supply systems. We show how to measure crosstalk easily.

The voltage regulator crosstalk is an important characteristic of systems with multiple regulators. We show how the measurement is performed using the Bode 100 and the Picotest J2111A Current Injector.

For this application note the Picotest VRTS 1 board provided the device under test. Crosstalk is an important characteristic of power supply systems with multiple voltage regulators. Especially if the regulators are connected to a single supply bus, crosstalk can lead to problems. Crosstalk is mainly caused by load perturbations that pass through the regulator due to poor Reverse Transfer. This load ripple then appears on the supply bus. Bad PSRR of another regulator could let this ripple pass to the output of the regulator and disturb any load.

This characteristic can be measured over the full frequency range from 1 Hz to 40 MHz using the Bode 100 in conjunction with the Picotest J2111A Current Injector. In this application note we provide a step by step guide on how to perform this measurement.