-SCS Parameter Analyzer Reference Manual Section 3: Source-
4200A-901-01 Rev. C / February 2017 3-23
Source-measure concepts
• Guarding (on page 3-23): An overview of guarding, guarding concepts, guard connections, and
test fixture guarding.
• Remote sensing (on page 3-29): Covers an overview of sensing, sensing concepts, and sense
selection.
• Sink overview (on page 3-30): Provides an overview of sink operation and summarizes sink
operating boundaries.
• Source-measure considerations (on page 3-31): Details various source-measure circuit
configurations, including Source V, Measure V, and measure-only.
• Sweep concepts (on page 3-34): Covers the source-delay-measure cycle and provides an
overview of sweep waveforms.
Guarding
The purpose of guarding is to eliminate the effects of leakage current (and capacitance) that can exist
between FORCE and COMMON, or between SENSE and COMMON. The driven GUARD is always
enabled and provides a buffered voltage that is at the same level as the FORCE or SENSE HI
voltage (GUARD for both SOURCE and SENSE are the same signal that is referenced in FORCE). In
the absence of a driven guard, leakage in the external test circuit could be high enough to adversely
affect the performance of the SMU or preamplifier.
Leakage current can occur through parasitic or non-parasitic leakage paths. An example of parasitic
resistance is the leakage path across the insulation in a triax cable. An example of non-parasitic
resistance is the leakage path through a resistor that is connected in parallel to the DUT.
To avoid high voltage exposure that could result in personal injury or death, whenever the
interlock of the 4200A-SCS is asserted, the FORCE and GUARD terminals of the SMUs and
preamplifier should be considered to be at high voltage, even if they are programmed to a
non-hazardous voltage current.
Guard connections
GUARD is available at the inner shield of the FORCE and SENSE triaxial connectors for both the
SMU and the preamplifier, as shown in the next figure.
Figure 55: SMU and Preamplifier triaxial connectors
To Next Page
Loading...
Need help?
General
