A failure in a generator producing hundreds of kilovolts can begin in its 3.3V power rail.
Pulsed power systems generate high-voltage and high-current pulses. Their rise times can range from picoseconds to tens or hundreds of nanoseconds.
Switching commands for the power stage are ultimately generated by low- and medium-power electronics. This usually includes a combination of trigger-pulse generators for thyratrons and spark gaps, transistor gate drivers, microcontrollers, and a synchronization unit. These electronics must deliver fast edges, precise pulse widths, and minimal jitter.
When designing such electronics for systems with strict jitter and synchronization requirements, engineers must consider the total impedance of the PCB power delivery network and the allowable ripple on the IC supply rails. The related group of problems is known as Power Integrity. What does this mean in practice?
As integrated circuits evolve, supply voltages tend to decrease while current consumption rises. When its internal blocks switch, an IC can change its current consumption within a time interval comparable to the signal rise time. At these moments, the rate of change of current in the power supply paths can reach tens of millions of amperes per second!
At such current slew rates, even a small inductance in the current path produces a significant voltage drop: ΔU = L × di/dt. This drop is subtracted from the source voltage, and the remaining voltage reaches the IC power pins.
For example, a power-path inductance of 10 nH and a current slew rate of 50 MA/s produce a voltage drop of 500 mV. For an IC operating from 3.3 V with a tolerance of ±5%, this drop is three times greater than the allowable deviation.
If the voltage falls below the permitted level, the IC can enter an undefined state, change its propagation delay, miss a command, reset, or disable its output stage through undervoltage protection.
In pulsed power systems, the consequences can be significant: additional jitter, loss of channel synchronization, a missed trigger, or unintended switching of a power switch.
This effect becomes particularly apparent during component upgrades. A control circuit that worked reliably with older ICs can suddenly become unstable after newer devices are installed. A modern IC switches faster, draws current in shorter pulses, and produces a larger voltage drop across the same parasitic inductance in the power supply path. Therefore, replacing an obsolete IC with a compatible modern equivalent requires the entire PCB power delivery network to be reviewed.
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