Low profile slide screw tuners and method
View Patent ↗A low-profile passive slide screw load pull tuner is used on-wafer, especially in millimeter-wave frequencies from 25 to 110 GHz and above. It uses special rotating tuning probes insertable in a short slabline mounted inside the tuner housing, which holds the control gear. The tuner is mounted at an angle matching the angle of the wafer-probe, is connected directly of the wafer-probe and ensures optimum reflection factor tuning range.
1. A load pull test setup for measuring RF transistor chips on wafer, comprising:
a low-profile electro-mechanical load pull tuner,
a wafer probe station with wafer probes,
a 3-axis tuner positioner with wedge interface;
wherein
the low-profile electromechanical load pull tuner comprises:
a low loss slabline having a center conductor, a longitudinal slot with a longitudinal axis, a coaxial test port and a coaxial idle port,
at least one metallic tuning probe, movable along and insertable into the slot of the slabline;
the wafer probe station comprises:
a station platform with support of a semiconductor wafer,
a microscope,
a set of wafer probes having a body and a coaxial connector attached to the body with a slope of an angle Φ;
the 3-axis tuner positioner with wedge interface comprises:
a 3-axis (X-Y-Z) positioner mounted on the platform of the wafer probe station, and
a wedge interface connecting the electro-mechanical load pull tuner with the 3-axis positioner,
wherein
the wedge interface has an inclined surface matching the angle Φ of the coaxial connector of the wafer probe,
and wherein
the test port of the electromechanical load pull tuner is connected directly with the coaxial connector of the wafer probe.
2. The low-profile electromechanical load pull tuner of claim 1
wherein
the tuning probe is a metallic disc, which rotates eccentrically around an axis perpendicular to the longitudinal axis of the slabline and is moved along the slabline by a first, remotely controlled, stepper motor and gear and is rotated by a second, remotely controlled, stepper motor and gear,
and wherein
the electro-mechanical load pull tuner is encapsulated inside a solid, low-profile tuner enclosure.
3. The 3-axis tuner positioner with wedge interface of claim 1 having
an X-axis parallel to the slabline, a Y-axis perpendicular to the slabline and a vertical Z-axis,
each said axis being controlled manually using micrometric screws, and
a wedge-form interface adapter attached to the vertical axis of the positioner and to the enclosure of the impedance tuner,
wherein
the wedge-form interface adapter can be rotated against the vertical axis.
4. A method for establishing direct RF contact between the low-profile electro-mechanical load pull tuner and the wafer probe of claim 1 ,
wherein
the coaxial connector of the tuner test port is aligned with and connected directly to the coaxial connector of the wafer probe.
5. The low-profile electromechanical load pull tuner of claim 2 ,
wherein
the tuning probe is placed close to the test port.