A novel active load-pull system with multi-band capabilities

In this paper a novel active open-loop multi-band load-pull measurement system is presented. The system uses few components where the main parts are an Oscilloscope and an Arbitrary Waveform Generator (AWG). The used AWG is a sophisticated signal generator with two outputs, letting the user take full control over the injected signals in the frequency band 0-4 GHz. This enables new kinds of measurements to be performed, such as multi-band load-pull and in particular inter-modulation product load-pull, which this paper focuses on. The paper describes the measurement setup briefly and the calibration and load-pull algorithms used. As an example to demonstrate the capabilities of the system, a multi-band load-pull is carried out on a GaN HEMT transistor. The frequency bands are 2.14 GHz and 2.65 GHz which create IM3 products at 1.63 GHz and 3.16 GHz. It is shown that the efficiency is affected by the choice of load termination presented at the IM3 frequencies.