Agilent 4155B/4156B User’s Guide Vol.2, Edition 5 8-7
If You Have A Problem
When You Make A Measurement
If Noise Affects the Measured Values
When you measure low current of a DUT, the measured values may not be stable.
To solve this problem:
• Use guarding to reduce the leakage current between your prober and the
4155B/4156B. Note that long wires cause oscillation because of their large
inductance. For details about connections, refer to “To Make Connections to
Reduce Leakage Current” in Chapter 4.
• If some high-power electric machines are operating around the 4155B/4156B,
turn off the machines, then perform the measurements. The machines affect the
power line waveform.
• Shut the lid of test fixture or shield box to prevent effects of light.
• If these are vibrations due to nearby machines or due to air flow, put cushioning
material under prober, cable, and the 4155B/4156B; install stabilizer on the
prober; and make the cables stable by taping.
• Wait several minutes after connecting cables or moving probe needles. Because
these operations cause electromotive force.
• If you use only Force terminal and triaxial cables for HRSMUs or HPSMU,
connect an open cap to sense terminal.
• Keep constant temperature in the room when you use the 4155B/4156B. Shift of
1 °C may shift the measurement values. Temperature change causes the
following.
• Offset current in the 4155B/4156B.
• Thermoelectromotive force in DUT, which causes low current.
• Expansion and contraction of cables, which causes noise.
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