Coplanar load pull test fixture for wave measurements
Coplanar waveguide microwave transistor test fixtures include integrated wideband signal sensors/couplers and allow the detection of the main signal and its harmonic components, generated by a transistor in high power operation mode, by using a phase-calibrated network or signal analyzer and thus the reproduction of real time signal waveforms.
1. A coplanar waveguide (CPW) test fixture for RF (radio frequency) transistors (device under test, DUT) comprises
at least one input test port and at least one output test port,
at least one main transmission line connecting the input test port with an input terminal of the DUT, and
at least one main transmission line connecting an output terminal of the DUT with the output test port, and
at least one directional signal coupler,
wherein
the at least one directional signal coupler is integrated in the test fixture and placed close to the DUT, between a test port and the associated DUT terminal, and is electro-magnetically coupled to the main transmission line, in a non-contacting relationship,
and wherein
the at least one directional signal coupler samples a portion of a transmitted signal and can be operationally connected with a signal analyzer to measure the portion of the transmitted signal.
2. The directional coupler(s) of claim 1 comprising
two coplanar waveguide (CPW) coupling lines and one coupled CPW section, wherein
the CPW section is placed parallel, in proximity and coupled electro-magnetically with a main CPW transmission line, and wherein
each end of the coupled CPW section is connected to one end of an associated coupling CPW line,
and wherein
the other end of the coupling CPW line is connected to a coaxial connector attached to the test fixture.
3. The test fixture of claim 2 comprising two signal couplers, one between the input test port and the DUT input terminal and one between the DUT output terminal and the output test port.
4. The test fixture of claim 1 comprising
two coplanar waveguide (CPW) coupling lines and one conductive wire bridge, wherein
the wire bridge is placed in proximity and coupled electro-magnetically with a main CPW transmission line in a non-contacting relationship,
and wherein each end of the wire bridge is connected to one end of an associated coupling CPW line,
and wherein the other end of the coupling (CPW) line is connected to a coaxial connector attached to the test fixture.
5. The test fixture of claim 2 ,
wherein
the transmission and coupling lines have characteristic impedance Zo=50 Ohms.
6. The test fixture of claim 2 ,
wherein
the transmission lines have characteristic impedance Zo=50 Ohms
and wherein
the coupling lines have characteristic impedance Zc>Zo.