Heterodyne active electronic load pull tuner
View Patent ↗A heterodyne, wideband active load pull tuner allows creating and controlling the reflection in a different frequency range than the operation frequency. It comprises an active feedback loop and a digital electronic tuner, wherein the electronic tuner operates at a single frequency while the active loop is wideband. This is achieved using a pair of down- and up-conversion stages, driven by an external signal source (local oscillator) which tracks the operation frequency and creates a fixed intermediate frequency, which is processed by the electronic tuner. This, two-frequency operation bypasses all circulator and electronic tuner bandwidth limitations and uses readily available large band components such as mixers and amplifiers.
1. A heterodyne active load pull tuner comprising:
a) a first coupling section having input, output and coupled port,
b) an up- and a down-conversion section,
c) a digital electronic tuning section,
d) an amplifier having input port and output port and
e) a second coupling section having input, output and coupled port,
wherein
signal extracted from a device under test (DUT) is sampled by the first coupling section and injected into (i) the up- or (ii) the down-conversion section;
the signal extracted from the conversion section is injected into the digital tuning section, the signal extracted from the tuning section is injected into (ii) the down- or (i) the up-conversion section correspondingly,
the signal extracted from the conversion section is injected into the amplifier and the signal extracted from the amplifier is injected back into the DUT via the second coupling section.
2. The tuner of claim 1 , wherein
the first coupling section is adjustable and comprises:
a low loss transmission line (slabline) having a test port and an idle port,
wherein the idle port is the output port of the first coupling section, and
a mobile carriage travelling along the slabline and having a mobile vertical axis,
and a wave-probe attached to the vertical axis and insertable into the slabline.
3. The tuner of claim 1 ,
wherein
the conversion section comprises:
a down-converter and an up-converter, a
low pass filter (LPF) and
a high pass filter (HPF);
each converter being a mixer having RF port, LO port and IF port
and each filter having input port and output port.
4. The tuner of claim 1 ,
wherein
the digital tuning section comprises:
a remotely controlled digital electronic tuner having a test port and an idle port,
a circulator having ports 1, 2 and 3,
wherein port 1 is the input port, port 2 is connected to the test port of the electronic tuner and port 3 is the output port,
and wherein
the idle port of the electronic tuner is terminated with characteristic impedance.
5. The tuner of claim 2 or claim 3 or claim 4 ,
wherein
the LO ports of mixer 1 and mixer 2 are connected to an external local oscillator, the RF port of mixer 1 is connected to the coupled port of the first coupling section, the IF port of mixer 1 is connected to the input port of the low pass filter,
the output port of the low pass filter is connected to port 1 of the circulator, port 2 of the circulator is connected to the test port of the electronic tuner, port 3 of the circulator is connected to the IF port of mixer 2,
the RF port of mixer 2 is connected to the input port of the high pass filter,
the output port of the high pass filter is connected to the input port of the amplifier,
the output port of the amplifier is connected to the coupled port of the second coupling section,
the input port of the second coupling section is connected to the output port of the first coupling section,
the output port of the second coupling section is terminated with characteristic impedance.
6. The tuner of claim 2 or claim 3 or claim 4 , wherein
the LO ports of mixers 1 and 2 are connected to an external local oscillator,
the IF port of mixer 1 is connected to the coupled port of the first coupling section, the RF port of mixer 1 is connected to the input port of the high pass filter,
the output port of the high pass filter is connected to port 1 of the circulator, port 2 of the circulator is connected to the test port of the electronic tuner, port 3 of the circulator is connected to the RF port of mixer 2,
the IF port of mixer 2 is connected to the input port of the low pass filter,
the output port of the low pass filter is connected to the input port of the amplifier,
the output port of the amplifier is connected to the coupled port of the second coupling section,
the input port of the second coupling section is connected to the output port of the first coupling section,
the output port of the second coupling section is terminated with characteristic impedance.
7. The tuner of claim 1 , wherein
the second coupling section has coupling factor between approximately 3 and 6 dB.
8. The tuner of claim 1 ,
wherein
the frequency of an external local oscillator F LO tracks the frequency F RF of the signal extracted from the DUT by an intermediate frequency F IF =|F RF −F LO |.
9. The first coupling section as in claim 2 ,
wherein the horizontal movement of the carriage and the vertical movement of the axis are remotely controlled.
10. The tuner of claim 1 , wherein
the second coupling section is eliminated, and the output port of the amplifier is connected directly to the output port of the first coupling section.
11. The tuner of claim 1 , wherein
a pre-matching device is inserted between the output port of the first coupling section and the input port of the second coupling section.
12. The tuner of claim 1 ,
wherein
a pre-matching device is inserted between the output port of the DUT and the input port of the first coupling section.
13. The tuner of claim 1 , wherein
the second coupling section is a circulator,
and wherein
port 1 of the circulator is connected to the output port of the amplifier,
port 2 of the circulator is connected to the output port of the first coupling section,
and port 3 of the circulator is terminated with characteristic impedance.
14. The tuner of claim 1 , wherein
the first coupling section is a power divider having an input and two output ports, a first output port and a second output port,
and wherein
the input port is connected to the DUT output port,
the first output port is connected to mixer 1, and
the second output port is connected to the input port of the second coupling section.
15. The tuner of claim 1 , wherein
the second coupling section is a power divider having an input and two output ports, a first output port and a second output port,
and wherein
the input port is connected to the output port of the power amplifier,
the first output port is connected to the output port of the first coupling section, and
the second output port is terminated with characteristic impedance.
16. The tuner of claim 1 ,
wherein
the first coupling section is a first power divider and the second coupling section is
a second power divider, each power divider having an input and two output ports,
a first output port and a second output port,
and wherein
the output port of the DUT is connected to the input port of the first power divider,
the first output port of the first power divider is connected to mixer 1,
the second output port of the first power divider is connected to the first output port of the second power divider,
the input port of the second power divider is connected to the output port of the amplifier, and
the second output port of the second power divider is terminated with characteristic impedance.