An active load-pull set-up for the large signal characterization of highly mismatched microwave power transistors

The authors propose an active load-pull setup providing a solution to the problem of large signal measurement of highly mismatched microwave power transistors. The basic principle of the proposed measurement technique consists of using an appropriate mismatched power source to drive the output port of the device under test (DUT). It is possible to synthesize any highly mismatched load by using a classical active load-pull setup, but large incident power waves driving the output port of the DUT are required. If the phase of the injected power wave at the transistor output port is not properly controlled, the component may be damaged. The active load pull technique presented overcomes these limitations. A medium power silicon bipolar transistor was characterized at 1.8 GHz. A power silicon transistor was also characterized at 1.7 GHz under Class A operating conditions. Results are shown