Keithley 6058 source measure free download

File name 6058_source_measure.pdf

SOURCE-MEASURE UNITS INCREASE PRODUCTIVITY AND ACCURACY IN AUTOMATED TESTING Lee Stauffer Keithley Instruments, Inc. Introduction Source-Measure Units (SMUs) are more than the next generation of power supplies; they are fast-response, read-back voltage and current sources with high accuracy measurement capabilities, all tightly integrated in a single enclosure. They are designed for circuit and device evaluation where a DC signal must be applied to a device under test (DUT) and the response to that signal measured. Many are capable of 4-quadrant operation, acting as a positive or negative DC source or as a sink (load). They also provide highly repeatable measurements, typically with 61/2-digit resolution. Figure 1 illustrates a typical SMU measurement circuit. Figure 1. Simplified block diagram of an SMU configured to source V, measure I. The system can also be configured as a current source and parallel voltmeter. Traditionally, a combination of bench top instruments, such as voltage or current sources and digital multimeters or picoammeters, have been used for material testing and component characterization. A common type of data collection project is generation of current-voltage (I-V) curves to describe component or material behavior in a circuit. Using separate instruments to do this requires a significant amount of work to program each individual instrument, resolve timing issues, and properly connect signal and triggering cables. Using an integrated source-measure instrument can reduce the effort required to acquire data, generate I-V curves, and otherwise characterize device performance. Because source and measurement functions are designed simultaneously for tightly coupled operation, they have features that simplify set- up and operation. For example, this tight integration allows easy programming of source and measurement functions, such as speed and noise rejection tradeoffs. Most SMUs also have built-in voltage and current sweep features for automatic collection of I-V data, and a compliance limit function that assures the safety of a DUT and test personnel. As a rule, SMU measurement capabilities exceed those of almost any combination of similar individual instruments. This is particularly true when it comes to throughput and accuracy. The intimate knowledge of both source and measurement circuitry during design, and feedback between those circuits during operation, allows compensation techniques that produce excellent instrument characteristics. This includes nearly perfect input and output impedances that can be dynamically adjusted for specific operating conditions. Such tight integration allows fast source-measurement cycles with superior resolution. Nowhere are these advantages more apparent than in semiconductor measurements, which are conducted on work-in-process wafers, as well as on finished products. In addition to measuring I-V