
DAC Speed and Glitches
Choose Subtopic
But it's even worse than that. Any wire has inductance, the storage of magnetic energy in a field surrounding the conductor. This can set up oscillations, as energy is stored, alternately, as charge in the capacitor or magnetization in the field. Absent resistance, the frequency in Hertz is 1/(2 π (LC)^{1/2}). For 10 nH (10 nanohenries inductance) and 10 pF, the frequency is 160 MHz. "So fast it couldn't matter." Except there can be little sine waves running around the circuitry, flipping high speed switches and adding noise! A wellengineered circuit will have low enough L and C that other problems, described below, will limit how rapidly a DAC (or other circuit component) will work. Circuit boards also have R, L, and C, and can degrade the function of even the bestdesigned components.
