Agilent Testing Circuit Board Power Distribution Using Real World Distortions - Application Note 5991-1330EN free download

File name Testing Circuit Board Power Distribution Using Real World Distortions - Application Note 5991-1330EN

Keysight Technologies Testing Circuit Board Power Distribution Using Real World Distortions Application Note Introduction The Role of a Pulse Function Arbitrary Noise Generator in Stress Test Applications Situation analysis In this digital era, embedded design engineers are using integrated circuits (ICs) to solve electronic challenges. Populated on printed circuit boards (PCBs), the ICs typically receive power from a central supply. With each IC used, its impact on electrical power must be considered. Most ICs draw current only when changing electrical states and this irregular power use introduces distortions to the power supply network. Such signal distortions potentially interfere with other circuits and raise the electrical noise level. This leads to reduced signal-to-noise ratios and affects the signal integrity on the outputs of the ICs. In a worst case scenario, noise can negatively affect the operation of the IC. Fluctuating voltage levels can interfere with correct IC operation as well. To limit the effect of these irregularities, hardware engineers use an array of protective circuits. Common methods to safeguard ICs include using a decoupling capacitor to counter voltage luctuation, and incorporating an inductor to limit the noise level. Unfortunately, every compen- sation method used to minimize power distortions at the circuit has its limitations. For example, consider the use of a decoupling capacitor. Material imperfections within the capacitor lead to equivalent serial resistance. Capacitor and packaging lead to equivalent serial inductance. These parasitic effects negatively inluence the capacitor's technical characteristics. At high frequencies the capacitor behaves more like an inductor or resistor--defeating its original purpose in the circuitry. Solution Coniguration Testing components and compensation circuits under real-world conditions is essential. It is this process that allows engineers to assess the PCB's design and power consumption. Testing also provides engineers with the insight necessary to enhance the device's overall performance. Figure 1 illustrates an effective method for simulating real-world conditions during the design stages. The components of this solution are summarized in Table 1. Oscilloscope Oscilloscope L OUT0 OUT1 VCC DC power supply