Correlation analysis between a VNA-based passive load pull system and an oscilloscope-based active load pull system: A case study

This paper presents a case study of performance comparison between a passive load pull system that uses a vector network analyzer (VNA) as its receiver, and an active load pull system that uses a sampling oscilloscope. The objective of the comparison was to enable parallel research activities between two sites. The two systems are independently used to measure the same device under test, a packaged high-voltage laterally diffused metal oxide semiconductor (HVLDMOS) device at a fundamental frequency of 900MHz and under the same bias and drive settings. A simulation of the device performance is also performed using Agilent ADS to accompany the measurement results and to verify the accuracy of the device model. Results show that both load pull systems are well correlated within two times the measurement uncertainty and that the device model gives a good performance prediction. A further investigation is performed by manipulating the harmonic loads using the active load pull system to demonstrate its advantages over the passive system in discovering the true capability of the device under test in terms of drain efficiency.