Microwave Engineering Europe - October 2008 - (Page 42)

42 SYNTHETIC TEST environment used during development. This contributes to high yield and highly correlated measurement results. Throughput analyses — Traditional versus Synthetic Key time elements of the stimulus — measurement test process There are ﬁve key time elements in the stimulus-measurement test process: • DUT setup, including warm-up • Stimulus setup • Response setup • Calibration • Actual measurement. In a traditional system, a central computer or controller will have to coordinate all the steps of the test process. The calibration of the individual instruments has to be factored with the calibration of interconnecting cables, connectors, etc., which increases the measurement uncertainty from test station to test station. Also, one must establish some level of synchronization among the various instruments to ensure proper signal injection, capture, and analysis. For T-R modules, the DUT requires power, control, communication, monitoring, and needs to be synchronized with the rest of the equipment as well. In a synthetic system, the stimulus, response, and DUT interface are all tightly integrated and synchronized. The calibration is performed at the system level, up to the DUT interface. Consequently, sources of uncertainty are greatly reduced. The whole system operates as one homogeneous environment and not as a collection of several items. Five instruments versus one measurement channel Considering the measurements required by T-R modules, ﬁve traditional instruments are needed: spectrum analyzer, network analyzer, noise ﬁgure analyzer, modulation analyzer, and power meter. In a synthetic system, however, all necessary measurements are made through a single response channel, often utilizing common digitized data. In a synthetic system one does not need to switch among various instruments in order to make measurements and there is only one measurement channel versus several measurement channels to be considered. Optimizing measurement time Measurement time should only be limited by the performance and latency/settling characteristics of the DUT. Once this becomes the case, the test environment is optimized for speed. Figure 2: Pulse measurement test screen capture. Figure 3: Spectral/spurious measurement screen capture. For traditional equipment, measurement time depends on each of the instruments being used as well as the switching of measurement and data paths, synchronization, and central control/sequencing at the system level. Measurements in themselves cannot be optimized since they are rigidly associated with individual instruments and cannot take advantage of common, sampled/digitized data blocks. For synthetic systems, measurements can be optimized by sequencing the various computations to take advantage of common data blocks, which optimizes the measurement space. There is no switching of instruments and measurement/data paths and the environment is inherently synchronized, including the DUT. Control/sequencing takes maximum advantage of the capabilities of all system resources involved. Again, the environment is homogeneous and it allows for continuous computing, signal processing and conditioning operations. The selection decision Throughput and associated total cost to test dictate the choice Looking at various benchmark tests run on T-R modules, and considering test campaigns with an average of twenty different test cases, traditional rack-and-stack test systems require approximately three to four hours of test time. A highly optimized synthetic test environment requires only four to six minutes of test time, where one of these minutes is allocated to DUT warm-up time. Even considering benchmarking approximations and the time it would take to cycle DUTs in the production test environment, using a synthetic test environment can increase test speed by 30 times. When comparing the costs of these two types of systems, a hybrid synthetic test environment, when ﬁrst procured, is typically within 10 percent of the cost of a traditional rack-and-stack system. Considering the test time saved over a period of time, the hybrid synthetic test environment has superior cost Microwave Engineering Europe ● October 2008 ● www.mwee.com 040-041-042-043_MWEE.indd 42 3/10/08 15:45:56 http://www.mwee.com

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Microwave Engineering Europe - October 2008 Contents Comment News Cover Feature: AWR's AXIEM Software Brings 3D Planar Electromagnetic (EM) Simulation "Up Front" RFID: Augmented Reality: Beyond RFID and QR Codes for Mobile Phone Platforms Filters & Frequency Synthesis ZigBee Goes Green with Support for Smart Energy Simplify Mobile Data Applications and Services Test Enabling the State-of-the-Art in Automatic Test Equipment National Physical Laboratory Test Facility Aids Development of Next-Generation Antennas Selecting the Synthetic Test Environment for Transmit-Receive (T-R) Modules in a Phased Array Radar System Products Calendar

Microwave Engineering Europe - October 2008

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