Migrating from the 4268A/4288A Capacitance Meter to the E4981A Capacitance Meter

The E4981A capacitance meter provides the best combination of accuracy, measurement speed, and a wide range of ceramic capacitor measurements. The E4981A replaces the 4268A 120 Hz/1 kHz and the 4288A 1 kHz/1 MHz capacitance meters. The E4981A includes the same functionality, SCPI com­mands, and user interface which makes migration quite easy. This document provides all the information you need to migrate to the E4981A.

The 4268A has three measurement speeds (short, medium, long) and the 4288A has two measure­ment speeds (short and long), compared to the E4981A which has five measurement speeds (n = 1, 2, 4, 6 and 8). The measurement time is defined as the time from trigger to the end of measurement.

The accuracy of the E4981A is the same as the 4288A. The 4288A has two measurement speeds (short and long), while the E4981A has five measurement speeds (n = 1, 2, 4, 6 and 8). The accuracy at short on the 4288A is the same as 1 on the E4981A. The accuracy at long on the 4288A is the same as 8 on the E4981A. The accuracy calculation formula is the exactly same for both products. The measurement range for both is the same at 1 MHz and there are no 22 μF, 47 μF and 100 μF ranges at 1 kHz for the 4288A.

The accuracy of the E4981A is much improved from the 4268A. The 4268A has three measurement speeds (short, medium, long), where as the E4981A has five measurement speeds (n = 1, 2, 4, 6 and 8). The accuracy calculation formula is different for both products.

The handler interface is compatible with the 4268A/4288A. When using the 4268A/4288A handler interface at the factory setting, you can use the E4981A without any modification. The difference points are shown in the Table 14.

Turning off status register update

When the status register is not used, the measurement computation time (T5) can became 0.7 ms. (T5 is 1 ms at ON.) To turn off the status register, use the SCPI command of “STATus:OPERation:UPDate”. Refer to the E4981A programming manual.

Reducing the waiting time for analog measurements

The E4981A has the capability to reduce the waiting time for analog measurements. The waiting time shown below is included in the analog measurement time (T4). This is the system default measurement delay time

The scanner interface is compatible with the 4268A/4288A. When using the 4268A/4288A scanner interface at the factory setting, you can use the E4981A without any modification. The difference points are shown in Table 18.

Other Functions Comparison

Frequency shift at 1 MHz

• –2% is added.
• Synchronous source/source delay
• The function is the same as the 4268A.
• Trigger delay
• The function is the same as the 4268A/4288A.

Signal level compensation (SLC)

E4981A has the signal level compensation function instead of auto level control function of the 4268A. The signal level compensation avoids the signal level drop due to the cable resistance. SLC contributes faster signal level convergence than ALC of the 4268A. The SLC will have a level error when the dissipation factor is high.

E4981A SLC is available in the following measurement ranges

• 120 Hz: 220 μF, 470 μF, 1 mF range
• 1 kHz: 22 μF, 47 μF, 100 μF range