Section 3: Source-measure hardware Model 4200A-SCS Parameter Analyzer Reference Manual3-34 4200A-901-01 Rev. C / February 2017Sweep conceptsAlthough the SMU can be used for static source or measure operation, SMU operation usuallyconsists of a series of source-delay-measure (SDM) cycles (see the next figure) as part of a sweep(refer to Sweep waveforms (on page 3-35)).Source-delay-measure cycleDuring 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 externalcircuitry 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 tointeraction between the DUT and the SMU.When there is more capacitance seen at the output, there will be more settling time required for thesource signal. The actual delay needed can be calculated or determined by trial and error. For purelyresistive 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 byautorange.Figure 71: SDM cycle
