Compact millimeter-wave tuner
View Patent ↗A compact millimeter-wave slide screw impedance tuner allows reducing to a minimum the insertion loss between the tuner and the wafer-probe. The structure of the tuner uses a 1 mm slabline and adapters, an eccentrically rotating remotely controlled wideband tuning probe and a sliding rack on which the tuning-probe is attached; the position of the rack is controlled by a permanently anchored motorized pinion. The construction method allows for maximum compactness, needed in order to be able to attach the tuner directly on the wafer-probe and minimize the insertion loss, while maintaining key advantages of electro-mechanical tuners, such as robustness, linearity, simplicity, tuning resolution and calibration and compatibility with existing load pull software and technology.
1. A compact millimeter-wave slide screw impedance tuner comprising
a) a slabline comprising
two metallic sidewalls having a first sidewall and a second sidewall,
one test and one idle port with associated coaxial connectors, and
a center conductor between the ports;
b) a mobile rack, sliding freely on the top surface of the first sidewall;
c) a first pinion attached to the axis of a first motor, said motor being anchored on the first sidewall, and
wherein the pinion controls the sliding position of the rack;
d) a metallic disc-shaped tuning probe with concave rim, which rotates eccentrically, inserted between the walls of the slabline and is attached to and controlled by the axis of a second motor;
wherein
the axis of the second motor traverses perpendicular the rack through a hole in the rack and holds the disc probe,
and wherein
the second motor is mounted on a bracket which slides, together with the sliding rack, parallel to the slabline.
2. The tuner as in claim 1 , wherein the tuning disc-probe is oval.
3. The tuner as in claim 1 , wherein the tuning disc-probe is elliptical.
4. The tuner as in claim 1 ,
wherein
a second sliding rack is mounted on the top surface of the second sidewall of the slabline, parallel to and symmetrically to the first rack relative to a longitudinal axis of the slabline;
and a second pinion controlling the sliding position of the second rack; said second pinion being attached to and controlled by the axis of the first motor,
and wherein
the axis of the second motor traverses the second rack perpendicular through a hole in the second rack.
5. A test setup comprising
a) a tuner as in claim 1 ;
b) a set of wafer-probes #1 and #2;
c) flexible RF cables with coaxial connectors;
d) a support table;
e) a 3-axis tuner micro-positioner;
f) a wafer-probe micro-positioner;
g) auxiliary test instruments, comprising at least a signal source and a power meter;
wherein
wafer-probe #1 is connected to the input of a DUT,
wafer-probe #2 is connected to the output of the DUT,
the test port of the tuner is connected directly to wafer-probe #2,
the 3-axis micro-positioner is anchored on the support table,
the tuner is attached to the 3-axis micro-positioner,
wafer-probe #1 is attached to the wafer-probe micro-positioner,
wafer-probe #1 and the idle port of the tuner are connected to the auxiliary test instruments using the RF cables as follows:
the wafer-probe #1 is connected to the signal source,
the idle port of the tuner is connected to the power meter.
6. An in-situ calibration method of the setup of claim 5 comprising the following steps:
a) connecting the wafer-probe #1 and the idle port of the tuner to the test ports of a vector network analyzer (VNA);
b) withdraw (turn out) the disc-probe of the tuner;
c) perform TRL calibration of the VNA at wafer-probe reference plane at selected frequencies;
d) set the rotation angle and the horizontal position of the disc-probe at a multitude of states, measure s-parameters at one or more of the selected frequencies and save in calibration files for later use.
7. A test setup comprising
a) two tuners as in claim 1 , an input tuner and an output tuner;
b) a set of wafer-probes #1 and #2;
c) flexible RF cables with coaxial connectors;
d) a support table;
e) two 3-axis tuner micro-positioners;
f) auxiliary test instruments, comprising at least a signal source and a power meter;
wherein
wafer-probe #1 is connected to the input of a DUT,
wafer-probe #2 is connected to the output of the DUT,
the test port of the input tuner is connected directly to wafer-probe #1,
the test port of the output tuner is connected directly to wafer-probe #2, the 3-axis micro-positioners are anchored on the support table,
the tuners are attached to the 3-axis micro-positioners,
the idle ports of the tuners are connected to the instruments using the RF cables as follows:
the idle port of the input tuner is connected to the signal source,
the idle port of the load tuner is connected to the power meter.
8. An in-situ calibration method of the setup of claim 7 comprising the following steps:
a) connecting the idle ports of the tuners to the test ports of a vector network analyzer (VNA);
b) withdraw (turn out) the disc probes of both tuners;
c) perform TRL calibration of the VNA at wafer-probe reference plane at selected frequencies;
d) set the rotation angle and the horizontal positions of the disc-probe of the output tuner at a multitude of states, measure s-parameters at one or more of the selected frequencies and save in output calibration files for later use,
e) withdraw (turn out) the disc-probe of the output tuner;
f) set the rotation angle and the horizontal positions of the disc-probe of the input tuner at a multitude of states, measure s-parameters at the one or more selected frequencies and save in input calibration files for later use.