Section 3: Source-measure hardware
Model 4200A-SCS Parameter Analyzer Reference Manual
3-34
4200A-901-01 Rev. C / February 2017
Sweep concepts
Although the SMU can be used for static source or measure operation, SMU operation usually
consists of a series of source-delay-measure (SDM) cycles (see the next figure) as part of a sweep
(refer to
(on page 3-35)).
Source-delay-measure cycle
During each SDM cycle, the following occurs:
1. The source output level is set.
2. There is a wait for the source delay.
3. The measurement is made.
The delay phase of the SDM cycle, which is programmed by software, allows the source and external
circuitry to settle before the measurement is performed. Although the source itself settles quite quickly
(provided the unit is not in compliance), external V or I settling may take considerably longer due to
interaction between the DUT and the SMU.
When there is more capacitance seen at the output, there will be more settling time required for the
source signal. The actual delay needed can be calculated or determined by trial and error. For purely
resistive loads and at higher current levels, the sweep delay can be set to a minimum.
The measure time depends on the selected integration period, and it also can be extended by
autorange.
Figure 71: SDM cycle
