Scopes optimized for measuring power supplies
Rohde & Schwarz featured a demo of its model RTA4004 scope, an instrument particularly well suited to characterizing switch-mode power supplies thanks to a Bode analysis option. The Bode plot option uses the oscilloscope’s built-in waveform generator to create stimulus signals ranging from 10 Hz to 25 MHz. Measuring the ratio of the DUT signal input and output at each test frequency, the scope then plots gain logarithmically and phase linearly. The result is a quick determination of the gain and phase margin of switched-mode supplies or linear regulators. These measurements help determine the control loop stability. They can also gauge the power supply rejection ratio and characterize the transition of the regulator system to the regulated output.