Divergent Technologies

The more advanced load pull setup, known as Vector load pull or VNA-assisted load pull, introduces a higher level of sophistication and accuracy to the measurement process. In this setup, the forward (a1, b1) and reverse (a2, b2) traveling waves are measured using two directional couplers connected at the input and output of the Device Under Test (DUT). By capturing the “a” and “b” waveforms, vector load pull can calculate the real-time tuner impedance presented to the DUT, reducing reliance on tuner calibration and enhancing measurement accuracy.

While tuner calibration is beneficial for steering tuning into the correct area of the Smith chart efficiently, the real-time calculation of tuner impedance based on measured waveforms provides a dynamic and adaptable approach to load pull measurements, optimizing performance and results.

In a typical vector load pull setup, components such as two bi-directional couplers, source and load tuners, and a Vector Network Analyzer with receiver access capability are essential. Absolute calibration at the DUT reference plane is crucial for fully computing the 8-term error model, ensuring accurate measurement results without leaving behind composite terms that may compromise measurement precision. This calibration method allows for a comprehensive assessment of the DUT’s performance under various load conditions, providing valuable insights for optimizing device design and performance.