A kind of dielectric substrate dielectric constant measurement mechanism and its measurement method
Technical field
The invention belongs to microwaves and millimeter-wave technology field, and in particular to a kind of Jie based on substrate integration wave-guide resonant cavity
Matter substrate dielectric constant measurement mechanism and its measurement method.
Background technique
Dielectric substrate dielectric constant measurement method mainly has lumped-circuit method, Resonant-cavity Method, Transmission line method and freedom at present
Space law etc., wherein Resonant-cavity Method is the most frequently used and accurate one kind.Especially after substrate integration wave-guide proposition, substrate collection
It solves that conventional metals wave guide resonance cavity volume is big, is difficult to the disadvantages of integrated at waveguide resonant cavity, is widely used.But
It is that the impedance of substrate integration wave-guide resonant cavity feed structure itself produces biggish interference to the extraction of resonant cavity free-running frequency,
In order to remove the influence of resonant cavity feed structure, some scholars propose in succession Foster Circuit equivalent-circuit model with it is humorous
Vibration chamber De- embedding method.These methods are effective and reliable in some scenes, but these methods only considered feed
Influence after structure and resonant cavity cascade, has ignored influence of the feed structure to cavity resonator structure itself.This is nothing at low frequency
Fasten and want, but under millimeter wave, submillimeter wave even Terahertz scene, due to feed structure with it is in resonant cavity size comparable
Quasi-, feed structure is very important to " destruction " of cavity resonator structure.This results in traditional Extraction medium substrates with respect to dielectric
The method of constant has been difficult to meet high-precision requirement.
It is therefore desirable to which new technical solution solves the above problems.
Summary of the invention
Goal of the invention: in order to overcome the deficiencies in the prior art, provide it is a kind of can be improved measuring accuracy based on
The dielectric substrate dielectric constant measurement mechanism and its measurement method of substrate integration wave-guide resonant cavity.
Technical solution: to achieve the above object, the present invention provides a kind of dielectric substrate dielectric constant measurement mechanism, including sets
Set the identical substrate integration wave-guide resonant cavity of at least three cavity sizes on medium substrate, each substrate integration wave-guide
The inside cavity middle of resonant cavity is provided with metalized blind vias, and the size of all metalized blind vias is not identical, the substrate
The top layer of integrated wave guide resonance chamber is provided with coplanar waveguide ground and GSG pads structure, the coplanar waveguide ground and GSG
The feed structure of pads structure composition substrate integration wave-guide resonant cavity, the coplanar waveguide ground respectively connected substrate and integrate wave
Lead resonant cavity and GSG pads structure.
A kind of dielectric substrate dielectric constant measurement method based on substrate integration wave-guide resonant cavity, includes the following steps:
1) vector network analyzer is contacted and be connected to probe by GSG pads structure, pass through vector network analyzer
Measure the cascade scattering parameter of each the substrate integration wave-guide resonant cavity and GSG pads structure;
2) the no-load resonance frequency of substrate integration wave-guide resonant cavity is extracted using De- embedding formula and perturbation principle;
3) according to obtained no-load resonance frequency, dielectric substrate dielectric constant is calculated using resonance equation.
Further, the De- embedding formula in the step 2 are as follows:
Or
Wherein formula (1) is from First Foster ' s Form derivation, and formula (2) is by Second Foster ' s
Form is derived, wherein fLThere are load resonance frequency, f for substrate integration wave-guide resonant cavityuFor no-load resonance frequency;QeFor feedback
Electric network external sort factor, QLFor substrate integration wave-guide resonant cavity loaded quality factor, can directly be obtained from scattering parameter,
QuFor the Q-unloaded of substrate integration wave-guide resonant cavity;xeFor feeding network reactance, beFor feeding network susceptance, k is outside
The feeding network coefficient of coup;B is the metalized blind vias about substrate integration wave-guide intra resonant cavity to substrate integration wave-guide resonance
The coefficient that chamber no-load resonance frequency influences, the size and 2 volume V of substrate integration wave-guide resonant cavity of the coefficient are inversely;C is
The coefficient that substrate integration wave-guide resonant cavity no-load resonance frequency is influenced about feed network structures itself;Formula (1) (2) are opened up
Minterm is opened and is neglected, then is had:
Wherein
Coefficient relevant to feeding network is only contained in above-mentioned formula (4) in this way;
According further to perturbation principle, obtain:
B=-2V1 (5)
Wherein V1It is the volume of substrate integration wave-guide intra resonant cavity metalized blind vias;
As substrate integration wave-guide intra resonant cavity resonance f101When mode, no-load resonance frequency fuIt is opposite with dielectric substrate to be situated between
Electric constant εrRelationship it is as follows:
Wherein aeffWith deffThe respectively equivalent length and equivalent width of substrate integration wave-guide resonant cavity, integrated wave guide resonance
The equivalent length a of chambereffWith physical length aSIWRelationship it is as follows:
Wherein d is the diameter of substrate integration wave-guide resonant cavity plated-through hole, and s is between the center of adjacent metal through-hole
Away from the no-load resonance frequency f for extracting substrate integration wave-guide resonant cavity in step 3uAfterwards, Jie is acquired according to resonance equation (6)
The relative dielectric constant ε of matter substrater。
Higher figure of merit is obtained in order to not destroy cavity resonator structure as far as possible in the present invention, coplanar waveguide ground usually works
In undercoupling state.
In the present invention when feed structure influences negligible to resonant cavity no-load resonance frequency, it is only necessary in medium substrate
Two substrate integration wave-guide resonant cavities of upper production can extract the relative dielectric constant of dielectric substrate.
The quantity that substrate integration wave-guide resonant cavity is promoted in the present invention is available more accurate as a result, in a certain range
Interior quantity is more, as a result more accurate.
The utility model has the advantages that compared with prior art, the present invention having following advantage:
1) measurement result is accurate, the method for the present invention it is innovative by feed structure impedance and feed structure itself to resonant cavity
In the influence of no-load resonance frequency is considered in, while the method for extraction dielectric constant even can by way of Simultaneous Equations
To remove the influence of the external factor such as the probe of connected vector Network Analyzer and transmission line structure, thus measurement result is more
Accurately, measurement accuracy is improved;
2) measurement process is simple, and traditional measurement method based on circuit model needs to measure Smith's original image and passes through function
The means such as fitting extract key parameter, and the method for the present invention only needs simply to measure the scattering parameter of sample you can learn that letter needed for all
Breath, in addition the method for the present invention can be with the influence of all external connection devices of De- embedding or transformational structure, and does not need additional
Measurement and analysis.
Detailed description of the invention
Fig. 1 is the sectional perspective schematic diagram of dielectric constant measurement structure of the invention;
Fig. 2 is the partial top view of dielectric constant measurement structure of the invention;
Fig. 3 is the schematic diagram of the sample one of the embodiment of the present invention 1;
Fig. 4 is the schematic diagram of the sample two of the embodiment of the present invention 1;
Fig. 5 is the schematic diagram of the sample three of the embodiment of the present invention 1;
Fig. 6 is the schematic diagram of the sample four of the embodiment of the present invention 2;
Fig. 7 is the schematic diagram of the sample five of the embodiment of the present invention 2;
Fig. 8 is the schematic diagram of the sample six of the embodiment of the present invention 2.
Specific embodiment
In the following with reference to the drawings and specific embodiments, the present invention is furture elucidated.
Embodiment 1:
As depicted in figs. 1 and 2, with a thickness of hsubThree substrates are respectively set on the medium substrate 1 of=6.52um and integrate wave
Resonant cavity 2 is led, the cavity size of three substrate integration wave-guide resonant cavities 2 is 340um × 340um, three substrate integration wave-guides
The inside cavity middle of resonant cavity 2 is provided with metalized blind vias 3, the respectively first rectangular metalized blind vias 31, second party
Shape metalized blind vias 32, the first rectangular metalized blind vias 33, are just respectively formed sample 1,2 and of sample on medium substrate 1 in this way
Sample 3, referring in particular to Fig. 3~Fig. 5.In the present embodiment three metalized blind vias 3 be square structure and side length it is identical, height not
Together, the height of the first rectangular metalized blind vias 31 is h1=0um, side length l1=8um;The height of second rectangular metalized blind vias 32
Degree is h2=2.76um, side length l1=8um;The height of third square metalized blind vias 33 is h3=5.52, side length l1=
8um。
The top layer of substrate integration wave-guide resonant cavity 2 is provided with coplanar waveguide ground 4 and GSG pads structure 5, is grounded coplanar
Waveguide 4 and GSG pads structure 5 form the feed structure of substrate integration wave-guide resonant cavity 2, and coplanar waveguide ground 4 respectively connected
Substrate integration wave-guide resonant cavity 2 and GSG pads structure 5, the probe of the size compatibility pitch=100um of GSG pads.
Specific implementation step is as follows:
1) vector network analyzer is contacted and be connected to probe by GSG pads structure 5, pass through vector network analysis
Instrument measures the cascade scattering parameter of each substrate integration wave-guide resonant cavity 2 and GSG pads structure 5, obtains sample by scattering parameter
Having for sheet 1 carries resonance frequency fL1=319.17GHz, loaded quality factor QL1=233.4479;Sample 2 has load resonance frequency
fL2=318.56GHz, loaded quality factor QL2=116.5168;Having for sample 3 carries resonance frequency fL3=318.72GHz, there is load
Quality factor qL3=71.3735;
2) it can be obtained by embedding formula (3)
It can be obtained by Perturbation Formulas (5):
Wherein 2 volume V=a of substrate integration wave-guide resonant cavityeff×deff×hsub, aeffWith deffRespectively substrate integrates wave
The equivalent length and equivalent width of resonant cavity are led, can be calculated by formula (7).
Simultaneous Equations (8) (9) calculate the no-load resonance frequency f of substrate integration wave-guide resonant cavityu=323.9GHz;
3) according to obtained no-load resonance frequency fu, dielectric substrate dielectric constant is calculated by following resonance equation (6)
εr:
Embodiment 2:
As depicted in figs. 1 and 2, with a thickness of hsubThree substrates are respectively set on the medium substrate 1 of=6.52um and integrate wave
Resonant cavity 2 is led, the cavity size of three substrate integration wave-guide resonant cavities 2 is 340um × 340um, three substrate integration wave-guides
The inside cavity middle of resonant cavity 2 is provided with metalized blind vias 3.Respectively square metalized blind vias 34, the 5th side
Shape metalized blind vias 35, hexagon metalized blind vias 36 are just respectively formed sample 4,5 and of sample on medium substrate 1 in this way
Sample 6, referring in particular to Fig. 6~Fig. 8.In the present embodiment three metalized blind vias 3 be square structure and the identical, side length of height not
Identical, the height of square metalized blind vias 34 is h4=5.52um, side length l4=0um;5th square metal blind hole 35
Height be h4=5.52um, side length l5=2um;The height of hexagon metalized blind vias 36 is h4=5.52um, side length are
l6=5um.
The top layer of substrate integration wave-guide resonant cavity 2 is provided with coplanar waveguide ground 4 and GSG pads structure 5, is grounded coplanar
Waveguide 4 and GSG pads structure 5 form the feed structure of substrate integration wave-guide resonant cavity 2, and coplanar waveguide ground 4 respectively connected
Substrate integration wave-guide resonant cavity 2 and GSG pads structure 5, the probe of the size compatibility pitch=100um of GSG pads.
Specific implementation step is as follows:
1) vector network analyzer is contacted and be connected to probe by GSG pads structure 5, pass through vector network analysis
Instrument measures the cascade scattering parameter of each the substrate integration wave-guide resonant cavity and GSG pads structure, is obtained by scattering parameter
Having for sample 1 carries resonance frequency fL4=319.17GHz, loaded quality factor QL4=233.4479;Having for sample 2 carries resonance frequency
Rate fL5=318.43GHz, loaded quality factor QL5=247.5742;Having for sample 3 carries resonance frequency fL6=317.33GHz, has
Carry quality factor qL6=248.4770;
2) it can be obtained by embedding formula (3)
According to above-mentioned theory, have:
Had according to Perturbation Formulas:
Wherein 2 volume V=a of substrate integration wave-guide resonant cavityeff×deff×hsub, aeffWith deffRespectively substrate integrates wave
The equivalent length and equivalent width of resonant cavity are led, can be calculated by formula (7).
Simultaneous Equations (10) (11) calculate the no-load resonance frequency f of substrate integration wave-guide resonant cavityu=
323.7GHz;
3) according to obtained no-load resonance frequency fu, dielectric substrate dielectric constant is calculated by following resonance equation (6)
εr:
Embodiment 3:
The present embodiment carries out the method for embodiment 1 and embodiment 2 with traditional several dielectric constant measurement methods respectively
Comparison, specific data are as shown in the table:
It can see according to upper table in high-frequency band, the De- embedding method of traditional dielectric constant measurement not only proposes precision
It rises without helping to deteriorate result instead.This is because in millimeter wave submillimeter wave or even Terahertz frequency range, feed structure with it is humorous
Chamber itself comparable size of shaking is quasi-, and influence of the feed structure to cavity resonator structure is very important.And the sheet that Examples 1 and 2 provide
It invents shown dielectric constant measurement method and shows the precision that the other conventional methods of the frequency range do not have, while this method
Easy to operate, process is simple, has larger application value.