A Novel Load-Pull Setup Allowing the Intermodulation Measurement of Power Transistors under Pulsed DC and Pulsed RF Conditions

This paper presents a novel measurement technique which for the first time, enables third order intermodulation measurements of power transistors under pulsed DC and pulsed RF conditions. The aim of the work reported here is to build a characterization tool allowing investigations on linearity of high power transistors versus thermal aspects and/or trapping effects. The proposed measurement tool is based on the use of a pulsed vector network analyzer (VNA) and a two-tone signal generator integrated in a load pull environment. The measurement set up is used for the characterization of GaN transistors (12times75mum² from Tiger foundry) at S band. Both RF power profiles and DC current/voltage profiles are measured using a pulsed VNA (for RF characterization) and a sampling scope (for DC measurements). Typically, the stimulus pulse width range is 2mus and a 10% duty cycle is applied. Power, linearity performances and DC consumptions of the transistor under test are recorded at different time positions within the pulse stimulus