Power integrity of your electronic designs
Accurate measurements to ensure power integrity in your electronic designs
Today’s highly integrated electronic devices use low voltage levels and components with far lower tolerances to fluctuations in power. Consequently, analyzing the performance of the power delivery network on a PCB is an important part of the circuit design process. Where previously measuring power level ripples, noise, and transients in the time domain was an adequate approach, frequency domain measurements are also essential to detect unintentional coupling with signals, resulting in power spikes. An additional factor to consider is potential high frequency responses up to several hundred megahertz during transient phases such as power-on surges and load changes, causing power rails to act as transmission lines, affecting the signal integrity.
Obtaining accurate time domain measurements to detect ripple, noise and transients of very small mV level signals on 1 to 3 V power rails accurately is a challenge. A suitable oscilloscope plus probes must feature a noise floor considerably lower than the anticipated peak-to-peak noise, for accurate ripple measurements. A fast update rate, high ADC resolution and a wide bandwidth are essential to capture fast disturbances and transients. To investigate unwanted signals coupled onto a power rail plus resulting harmonics in the frequency domain, an oscilloscope requires powerful FFT with a wide frequency bandwidth. While the power supply switching speed may be in the kHz range, fast edges produce harmonics that go well into the MHz range. The performance of the probe is important as an essential part of the instrument.
In addition, a power delivery network shall feature low impedance in the mΩ range, that ideally does not change with the frequency. To investigate the impedance in transient phases, a network analyzer with the required dynamic range for low impendence measurements, the necessary frequency range to include harmonics at up to several hundred MHz, and suitable probes, is the instrument of choice.
