The present invention refers to an ultra-wideband interconnection probe structure for electronic signals which combines dielectric waveguide elements with metal waveguide elements, which can be fabricated on different material substrates. The interconnection structure that results from this combination provides an ultra-wide bandwidth, with an operating frequency range can start at 0 Hz (DC) and reach up into the Terahertz range (300 GHz to 3000 GHz) and above.
To date, various interconnection standards for electrical signals have been defined, which used by the electronics industry in devices and instrumentation test equipment for device characterization as well as on a wide range of application fields, ranging from communication to spectroscopy-based sensor systems. A Vector Network Analyzer (VNA) is the main measurement platform for phase sensitive measurements in electronics. VNA's provide the only platform that has standardized calibration procedures accepted by industry to characterize the frequency response of electronic systems, from low frequency (few kHz) up into the millimeter-(MMW, 30 GHz to 300 GHz) and Terahertz (THz, 300 GHz to 3000 GHz) ranges. A VNA operates in the frequency domain, measuring the amplitude and phase of a signal interacting with an electronic device —both transmitted and reflected signals are measured simultaneously-, with the frequency being swept through the measurement band, providing frequency-dependent data. VNA systems are composed of a baseband unit (with a maximum frequency <67 GHz), fitted with standardized coaxial connectors. Through these connectors, using coaxial cables, one can connect frequency extension heads that enable to extend the maximum frequency to higher frequencies. While significant progress has been achieved in the fabrication of monolithic microwave integrated circuits (MMICs), there is a lack of new developments to push the limits of the current high-frequency electrical interconnects technology towards higher frequencies.
This lack is the cause of a limitation of VNAs broadband frequency extension heads, which use coaxial connector interfaces. In their more advanced versions cover a frequency range from 0 Hz (DC) to 133 GHz (using the 1 mm coaxial standard) or from Hz to 220 GHz (using the more advanced 0.6 mm coaxial standard). Aside from the cost of these connectors (over € 600 per unit for the 1 mm standard), one of the major problems is that coaxial connectors are reaching their physical limit with the 0.6 mm coaxial standard (the given dimension refers to the smallest inner diameter of the outer conductor). To further increase the maximum operating frequency, the coaxial connector must further reduce its size, which increases their fragility and has a direct impact on the number of contacts that can be made. More serious is the problem related to the repeatability of the measurements, even when qualified personnel perform these interconnects.
Another limitation appears when VNAs need to perform measurements at frequencies above the maximum frequency of the coaxial standards. The frequency extension heads that reach into the Terahertz frequency range rely on standardized rectangular metal waveguide interconnects, which define different waveguide flange sizes that introduce important limitations. The interconnects between two flanges must be as close to perfect as possible since at such short wavelengths, as any skew in a flange connection can cause unwanted reflections that will degrade signal quality and reduce signal power. This is more critical at THz, due to the smaller dimensions required. In the same way as coaxial connectors, the higher the frequency the smaller the size of the waveguides. This is also bringing rectangular metal waveguides beyond the current state of the art of routine industrial manufacturing. However, the most important limitation of rectangular metal waveguides is that the waveguide size establishes lower and upper cut-off frequencies, slicing the spectrum in frequency bands. As an example, the WR-2 standard operates from 325 to 500 GHz, with dimensions 508 μm×254 μm. These dimensions reduce to 254 μm×127 μm for WR-1, operating from 750 to 1100 GHz. These standards restrict the frequency range over which devices operate to the sub-band of the WR standard they have been provided, hindering the existence of systems or devices that can operate over different sub-bands. In addition, to take measures over different WR standards, one must measure in each sub-band with the appropriate pair of microwave extension heads, which makes the measurement considerably more difficult and prevents calibrated measurements across the entire frequency range.
The present invention aims to solve the aforementioned limitations in the existing connection interfaces.
The present invention relates to a new type of interconnection probe for electrical signals that provides an ultra-wide continuous operating frequency range, increasing the maximum frequency beyond the limit of current coaxial connector standards to the Terahertz range and beyond. In addition, this structure is highly versatile and can be used to interface with all current high frequency interconnect standards, either coaxial or any of the rectangular waveguide flange sizes as well as act as a wideband transmitter/receiver antenna for the frequencies within the operating range.
In the present disclosure, the versatility of this new electrical interconnect is demonstrated describing different interconnection scenarios that are enabled by this novel structure, as well as different configurations in which it can be arranged.
A first aspect of the present probe is that comprises a dielectric waveguide structure with a high-pass filter characteristic, enabling the electrical interconnection for signals with frequencies above a low cut-off frequency (fCL). The dielectric waveguide has a preferably rectangular section, comprising a first tapered end connectable to an access port of a first electronic device, the access port comprising a first tapered coupler. The dielectric waveguide comprising a second tapered end connectable to an access port of a second electronic device, the access port comprising a second tapered coupler.
For example, the dielectric waveguide structure can be designed to operate over a range starting at a low cut-off frequency (fCL) in the microwave range (i.e. between 3 GHz to 30 GHz) or in the millimeter-wave range (i.e. between 30 GHz to 300 GHz), e.g. at an operating frequency of 60 GHz covering a broad frequency range that extends into the Terahertz wave range (i.e. between 300 to 3000 GHz.) and beyond.
A second aspect of the present wideband interconnection probe is that it can further comprise a metal waveguide structure with a low-pass filter characteristic which enables to establish a metallic electrical contact between the access ports of the two electronic devices that allows the interconnection operating frequency range to start at low frequencies (i.e. preferably starting at DC, 0 Hz). This enables the electrical interconnection of signals from 0 Hz up to a high cut-off frequency (fCH) in the millimeter-wave range.
For example, the metal waveguide structure can be designed to operate over a range that starts at 0 Hz and extends up into the millimeter-wave range (i.e. between 30 GHz to 300 GHz, e.g. at an operating frequency of 100 GHz). In a preferred embodiment for wideband operation, this metallic waveguide structure operates over a frequency range that starts at low frequency (i.e. starting at DC, from 0 Hz) and extends above the low cut-off frequency of the dielectric waveguide structure (fCH>fCL, e.g. above the 60 GHz of previous example).
A third aspect of one example of wideband interconnection probe is that the metal waveguide structure can comprise a at least one tapered coupler structure matching the tapered ends of the dielectric waveguide providing at least one access port in the wideband interconnection probe. At the wider extreme of the tapered coupler, metal contact between the metal waveguide structure and the tapered coupler. This allows to establish the interconnection of low frequency signals through the metal waveguide structure, and the interconnection of the high frequency through the dielectric waveguide.
The dielectric waveguide and metal waveguide structures can be used independently to establish interconnects within their operating frequency ranges. In addition, the present disclosure allows the two structures to be combined to achieve a wideband operation of the interconnect probe operating from DC (0 Hz) to the Terahertz frequency range and above.
For a better understanding the above explanation and for the sole purpose of providing an example, some non-limiting drawings are included that schematically depict a practical embodiment.
In a preferential embodiment of this structure, the central section of the dielectric waveguide structure (120) has a rectangular shape and is terminated at the interconnect interface with a tapered section or tapered end (120a) while the access port of the electronic device (101) has a tapered coupler (101a) structure matching the first tapered end (120a) of the dielectric waveguide structure (120). As shown in
As for the connection at high frequencies, this is established by means of the dielectric waveguide structure (120), through near field coupling between the tapered end (120a) of the dielectric waveguide structure (120) and the metallic pattern of the tapered couplers (101a, 102a) of the electronic devices (101, 102). As shown in
Since the connection established by the metal waveguide structure (110) is used for low frequencies, the electrical and mechanical requirements of this interconnect are relaxed compared to existing transmission line interconnects through either two (Ground-Signal, GS) or three conductor (Ground-Signal-Ground, GSG) contact probes. The dimension of the contacts can be correspondingly larger (the contact area is 12 μm×12 μm on existing GSG probes in contrast to 500 μm×500 μm in the proposed design). In turn, the larger contact area also allows to increase the electrical bias power supplied to the devices through this hybrid interconnection probe (100). Furthermore, it facilitates the alignment and the survivability of the hybrid interconnection pro be (100) after repeated interconnections or in case of inexpert use.
As for the connection at high frequencies, this is established by means of the dielectric waveguide structure (120), through near field coupling between the tapered end (120a) of the dielectric waveguide structure (120) and the tapered coupler (101a) of the access port of the electronic device (101) to be connected.
The probe (300) comprises a metal waveguide structure defining a metal waveguide pattern (110a) with the shape of a tapered coupler, preferably a Tapered Slot Antenna “TSA” (TSA-1a) around the first tapered end (120a) of the dielectric waveguide structure (120) and which provides a RF access port (P) in the probe (300) which is the point at which electronic signals can be supplied or detected. Furthermore, the second tapered end (120b) is connectable to the access port of the electronic device (102) via the tapered coupler (102a).
Furthermore, the probe (200) comprises a metal waveguide structure (110) establishing a low-pass characteristic interconnect between a first port (P1) and a second port (P2) and which operates over a low frequency range from DC up to a high cut-off frequency ICH in the millimeter wave range.
The metal waveguide structure (110) of the probe (200) comprises a first metal waveguide pattern (110a) defining a first tapered coupler connectable to the first device (101), preferably a Tapered Slot Antenna “TSA” (TSA-1a) around the first tapered end (120a) of the dielectric waveguide structure (120) and a second metal waveguide pattern (110b) defining a second tapered coupler connectable to the second device (102), preferably a Tapered Slot Antenna “TSA” (TSA-1b) around the second tapered end (120b) and a substrate (140).
On the extremes of the ultra-wideband interconnection probe (200), signal access ports are provided, where ports (P1) and (P2) are the points at which electronic signals can be supplied or detected. In order to demonstrate the broadband characteristic of the interconnection ultra-wideband interconnection probe (200), port (P1) is used to inject a signal (transmitter port) and port (P2) to observe the signal (receiver port) interconnected by means of the proposed ultra-wideband interconnection probe (200) which behaves as a transmission line for a wide range of frequencies.
In one example, the permittivity of the dielectric waveguide elements that are stacked can be the same, processed in the same material. This is not a restriction of the present disclosure, in which the dielectric materials of each layer can be different. In
In the ultra-wideband interconnection probe (200) of
In one implementation, the proposed ultra-wideband interconnection probe (200) comprising the first and second metal waveguide patterns (110a, 110b) and the tapered ends (120a, 120b) of the dielectric waveguide structure (120) can perform as antennas. This allows defining the phase center of the radiated electromagnetic wave at each frequency to optimize the coupling between both structures, the metal waveguide structure defining TSA antennas (TSA-1a) and (TSA-1b) and the respective dielectric waveguide tapered ends (120a) and (120b). For ultra-broadband operation, the phase center of the electromagnetic wave on both structures must be overlapped at every frequency within the operating range. This can be achieved by using the same type of taper profile for both structures, the first and second metal waveguide patterns (110a, 110b) and the dielectric waveguide structure (120). A linear profile for both structures i.e. the first and second metal waveguide patterns (110a, 110b) and respective dielectric waveguide tapered ends (120a, 120b) has been used. This is the preferred implementation, with the same aperture angle in terms of simplicity and coupling. The present disclosure does not however limit to this profile, and other configurations can be considered, including the case where different ports can have different tapering profiles.
In another implementation, the proposed ultra-wideband interconnection probes (100, 200) comprising the first and second metal waveguide patterns (110a, 110b) and the tapered ends (120a, 120b) of the dielectric waveguide structure (120) can perform as a near field coupler.
Given the broad bandwidth, the ultra-wideband interconnection probes (100, 200) are electrically large at high frequencies, which allows higher order modes to propagate through the structure. By the arrangement overlapping the phase centers of the electromagnetic waves at all frequencies, an additional advantage of suppressing, or at least mitigating the excitation of higher order modes is achieved. When multimode propagation happens, signal drops appear in the transmission due to destructive interference among the modes that propagate at different speeds introducing dispersion.
The results shown in
In
Another advantage of the disclosed interconnect probes, which results from the extremely wide continuous operating frequency range of the proposed ultra-wideband interconnection probes relates to the capability to establish an interconnection with multiple rectangular and circular waveguide connectors, including IEEE Standards for Rectangular Waveguides.
Another advantage relates to the capability of the proposed ultra-wideband interconnection probe (100) to couple the signals to other dielectric structures. Since unlike coaxial cables and rectangular waveguides, the electromagnetic field propagating through the proposed ultra-wideband interconnection probe (100) is not confined within it, the dielectric waveguide structure (120) can be used for near field coupling to other dielectric structures. As an example,
Another advantage relates to the ability of the proposed ultra-wideband interconnection probes (100, 200) to radiate the electromagnetic wave propagating through the ultra-wideband interconnection probes into the air, as a free space antenna.
When the ultra-wideband interconnection probes (100, 200) are considered as an antenna, it immediately allows to develop transmitter and receiver devices, adding to the antenna a transmitter (for example, a photomixer) or a receiver (for example, a Schottky diode) devices at the TSA antenna of the first metal waveguide pattern (110a) of the ultra-wideband interconnection probes (100, 200). In the simulation, it is assumed a point source at access ports (P1) for the transmitter and (P2) for the receiver (
If DC bias is required for said device, a solution to make the required connections using high impedance lines which provide baseband signal access is shown. The bandwidth of this baseband access can be optimized for direct detection receivers.
When used as a receiver, the ultra-wideband interconnection probes (100, 200) allows to place a Schottky Zero Bias Diode (ZBD) envelope detector or other type of receiver element in (P3). With a Schottky ZBD, the received baseband signals can be detected through the bias connection, with baseband bandwidth from e.g. 0 to 600 MHz.
In order to increase said baseband bandwidth in either transmitter or receiver configuration, the ultra-wideband interconnection probe (100) of
In this design, port (P2) is a source of microwave signals—typically a modulated carrier, thus consisting of a certain bandwidth—that come through the dielectric waveguide structure (120) (or the bifilar line (110c)) to the diode located at (P3). The ultra-wideband interconnection probe (100) performs a baseband conversion of the modulated signal. The baseband signal is routed through (TSA-2a), the CPS line, the CPS-CPW transition to port (P1).
Number | Date | Country | Kind |
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20382960.1 | Nov 2020 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2021/080652 | 11/4/2021 | WO |