Transforming load pull test fixture for wave measurements

An impedance transforming test fixture with signal couplers for time domain measurement of RF transistors (device under test, DUT), comprising:

• an input metallic block with an input test port, an output metallic block with an output test port and
• a metallic block inserted between the input and output blocks, on which a DUT is mounted, and
• a main transmission line connecting the input test port with an input terminal of the DUT, and an output terminal of the DUT with the output test port,
• wherein
• the main transmission line comprises:
• one or more transforming section(s) with characteristic impedance Zc, lower than the characteristic impedance Zo of the transmission line, and signal coupler(s),
• and wherein
• the coupler(s) is/are placed close to the DUT, between the input and/or output test port and the associated DUT terminal, and is/are electro-magnetically coupled to the transforming section(s) in a non-contacting relationship,
• whereby
• the signal coupler(s) sample(s) a portion of a transmitted signal and can be operationally connected with a signal analyzer to measure the portion of the transmitted signal.