Accuracy & Scope Selection

Each IPC monitor is individually calibrated to a maximum output error of +0.5%, -0.0% at one particular frequency, typically 400Hz (5KHz for CM-100-xx models). For best accuracy, it is important that a precision 50Ω feed-through termination is used at the scope. For a bandwidth extending from a decade above the lower 3 dB limit and a decade below the upper 3 dB limit the response is substantially uniform. At the lower frequency end, the sensitivity decreases steadily and drops off at the rate of approximately 6 dB per octave.

In contrast, at the higher frequency end it is quite common that the response oscillates before exceeding the 3 dB limit. IPC monitors incorporate means to make the response less sensitive to the location of the primary conductor within the monitor opening. However, for best high frequency response it is still advisable to center the monitor around the conductor. If a monitor is to be used at one particular frequency, IPC would be willing to calibrate the monitor to that frequency.

For best high frequency response, it is important that the scope or other voltage-sensing instrument has a bandwidth that is at least four times higher than the highest signal frequency.