CONDUCTOR TRACK ARRANGEMENT FOR HIGH-FREQUENCY SIGNALS, BASE AND ELECTRONIC COMPONENT HAVING A CONDUCTOR TRACK ARRANGEMENT

Abstract

A conductor track arrangement for high-frequency signals is provided. The arrangement includes a carrier, a ground conductor, and a pair of signal conductors. The signal conductors are layered and are arranged on the carrier opposite the ground conductor. A distance is between the signal conductors, which have a deflection region, in which a direction of the signal conductors changes. The deflection region has a reduced distance, which is reduced compared to the distance d between the signal conductors outside the deflection region. The distance between the signal conductors in transition regions from straight portions of the signal conductors into the deflection region is reduced here symmetrically with respect to an extension of a centre line between the two signal conductors into their respective straight portions and/or a capacitor is introduced into the signal conductor considered to be the inner signal conductor in respect of the direction change.

Claims

1. A conductor track arrangement for high-frequency signals, comprising: a carrier; a ground conductor; a pair of signal conductors formed in a layer and arranged on the carrier opposite the ground conductor; a distance (d) between conductors of the pair of signal conductors, and wherein the pair of signal conductors comprises a deflection region and a transition region, the pair of signal conductors changes direction in the deflection region, the pair of signal conductors having straight portions in the transition region leading into the deflection region; and a capacitor in the transition region.

2. The arrangement of claim 1, wherein the capacitor is provided by the pair of signal conductors, within the deflection region, having a reduced distance (d.sub.r) as compared to the distance (d) outside the deflection region and the distance (d) between the pair of signal conductors in the transition region reduces symmetrically with respect to an extension of a centre line between the conductors of the pair of signal conductors.

3. The arrangement of claim 1, wherein the conductor of the pair of signal conductors inward of the change in direction in the deflection region is an inner signal conductor, and wherein the capacitor is provided by an arrangement of an open-circuited stub electrically connected to the inner signal conductor.

4. The arrangement of claim 3, wherein the open-circuited stub has a length that is shorter than a quarter of a wavelength of a highest frequency for which the conductor track arrangement is configured.

5. The arrangement of claim 3, wherein the open-circuited stub has a conductive area in the form of a fan.

6. The arrangement of claim 1, wherein the capacitor is configured such that, for a signal guided by the pair of signal conductors, a phase difference between the pair of signal conductors caused by the direction change of the pair of signal conductors in the transition region is minimized.

7. The arrangement of claim 1, wherein reduction of the distance (d) to the reduced distance d.sub.r within the deflection region is continuous and has no steps.

8. The arrangement of claim 1, wherein the pair of signal conductors have, in the deflection region, a coupling factor between a common-mode and a differential-mode wave of at most −10 dB.

9. The arrangement of claim 1, wherein the ground conductor is a further conductive layer having a layer distance (D) between the further conductive layer and the conductive layer that lies in a range of from 0.025 mm to 0.65 mm.

10. The arrangement of claim 1, wherein the pair of signal conductors is arranged on a first side of the carrier and the ground conductor is a further conductive layer on a second side of the carrier.

11. The arrangement of claim 1, further comprising a ratio (d.sub.r/d) of the reduced distance d.sub.r in relation to the distance d that lies in a range from 0.1 to 0.95.

12. The arrangement of claim 11, wherein the range is from 0.4 to 0.8.

13. The arrangement of claim 1, further comprising a ratio (W.sub.r/W) of a reduced width (W.sub.r) of the conductors in the pair of signal conductors in the deflection region in relation to a width (W) outside the deflection region that lies in a range from 0.1 to 0.93.

14. The arrangement of claim 13, wherein the range is from 0.4 to 0.8.

15. The arrangement of claim 13, wherein the pair of conductors further comprises a narrowing region that lies outside the deflection region, wherein the reduced width (W.sub.r) is within the narrowing region.

16. The arrangement of claim 1, wherein the conductor of the pair of signal conductors has, within the deflection region, an edge with two or more curved portions, wherein the two or more curved portions have different radius of curvature.

17. The arrangement of claim 1, wherein the conductor of the pair of signal conductors has, within the deflection region, an edge with at least one straight portion.

18. The arrangement of claim 1, further comprising a feature selected from a group consisting of: a submount on which the conductor track arrangement is arranged; the carrier being made of a material selected from a group consisting of aluminium-nitride ceramic, aluminium-nitride-containing ceramic, aluminium oxide (Al.sub.2O.sub.3), glass, glass, and ceramic; a ratio (W/D) of a width (W) of the pair of signal conductors to a distance (D) between the ground conductor and the pair of signal conductors that lies in a range from 0.05 to 3; a ratio (W/D) of a width (W) of the pair of signal conductors to a distance (D) between the ground conductor and the pair of signal conductors that lies in a range from 0.1 to 2; a ratio (d/D) of a distance (d) between the conductors of the pair of signal conductors outside the deflection region to a distance (D) between the ground conductor and the pair of signal conductors that lies in the range from 0.05 to 3; a ratio (d/D) of a distance (d) between the conductors of the pair of signal conductors outside the deflection region to a distance (D) between the ground conductor and the pair of signal conductors that lies in the range from 0.1 to 1.5; a limit frequency for creation of waves of higher order that lies above 60 GHz; a limit frequency for creation of waves of higher order that lies above 70 GHz; and any combinations thereof.

19. A base for an electronic component, comprising: an electronic element; the conductor track arrangement of claim 1; and an electric feedthrough, and wherein the electronic element and the electric feedthrough are connected to the pair of signal conductors so that electrical signals are carried from the feedthrough, via the pair of signal conductors, to the electronic element.

20. An electronic component, comprising: an electronic element; the conductor track arrangement of claim 1; and a housing enclosing the electronic element and the conductor track arrangement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0066] FIG. 1 shows a schematic structure of a conductor track arrangement with two signal conductors and a ground conductor,

[0067] FIG. 2 shows a plan view of a conductor track arrangement according to the prior art,

[0068] FIG. 3 shows a plan view of a first embodiment of a conductor track arrangement according to the invention,

[0069] FIG. 4 shows a plan view of a second embodiment of a conductor track arrangement according to the invention,

[0070] FIG. 5 shows a plan view of a further embodiment of the conductor track arrangement with a radially opening stub.

[0071] FIG. 6 shows a graph illustrating the phase difference between the two signal conductors according to the second embodiment,

[0072] FIG. 7 shows a diagram illustrating the coupling factor between differential-mode and common-mode waves for a conductor track arrangement according to the second embodiment,

[0073] FIG. 8 shows a graph illustrating the insertion loss for a conductor track arrangement according to the second embodiment,

[0074] FIG. 9 shows an example of a base of an electronic component, said base comprising a conductor track arrangement according to the invention, and

[0075] FIG. 10 shows a second example of a base in which the conductor track arrangement has additional ground planes.

DETAILED DESCRIPTION

[0076] FIG. 1 schematically shows a conductor track arrangement 1 in a sectional view from the side. A differential triple line is shown, which comprises two signal conductors 10, 11 and a ground conductor 4.

[0077] In the example shown in FIG. 1, the conductors 4, 10, 11 are obtained by structuring conductive layers which are applied to a carrier 2. In the example of FIG. 1, a conductive layer, which forms the signal conductors 10 and 11 by structuring, is applied to an upper side of the carrier 2, and another conductive layer, which forms the ground conductor 4 by structuring, is applied to an opposite lower side of the carrier 2.

[0078] The two signal conductors 10, 11 have a distance d from each other and a width W. These geometric parameters of the signal conductors 10, 11 are determined by the structuring of the conductive layer. The ground conductor 4 is usually at least so wide that the width of the ground conductor 4 is greater than the sum of the widths W of the signal conductors 10, 11 and of the distance d between the two signal conductors 10, 11. The width of the ground conductor 4 is also set by corresponding structuring of the further conductive layer. A distance D between the ground conductor 4 and each signal conductor 10, 11 is specified here by the thickness of the carrier 2.

[0079] The ground conductor 4 and the two signal conductors 10, 11 are coupled. This means that the distance between the conductors 4, 10, 11 is so small that their electromagnetic fields overlap. When an electrical signal is introduced into the two signal conductors 10, 11, the signal conductors 10, 11 each have a voltage U.sub.1 and U.sub.2, respectively, to the ground conductor 4. Between the two signal conductors 10, 11 there is a voltage U.sub.diff=U.sub.1−U.sub.2. If the two signal conductors 10, 11 are actuated in differential mode with a phase difference of 180° and with the same amplitude, U.sub.diff has twice the amplitude compared to a single line with only one signal conductor 10, 11 and one ground conductor 4.

[0080] However, the double amplitude only occurs if the signals on both signal conductors 10, 11 have a phase difference of 180°.

[0081] FIG. 2 shows a conductor track arrangement 1 according to the prior art in a plan view. Starting from straight portions 21, the signal conductors 10, 11 are deflected by 90° within a deflection region 20. The ground conductor 4, compare FIG. 1, is located on the lower side, which is not visible, and is also deflected by 90°.

[0082] When the direction of the differential signal conductors 10, 11 is changed, as shown in FIG. 2, the symmetry is lost because the outer signal conductor 11 is always longer than the inner signal conductor 10. The inner signal conductor 10 has the arc radius R.sub.1 and the outer signal conductor 11 has the arc radius R.sub.2. Let the distance between the two signal conductors from centre to centre be P. The length difference ΔL results from the arc difference of the two quarter circles. With R.sub.2=R.sub.1+P, the length difference results in ΔL=π/2*P.

[0083] FIG. 3 shows a plan view of a first embodiment of a conductor track arrangement 1 according to the invention. The conductor track arrangement 1 again comprises two signal conductors 10, 11 and a ground conductor 4, compare FIG. 1, which are arranged on the opposite side of a carrier 2, so that the ground conductor 4 is not visible in the representation in FIG. 3.

[0084] The signal conductors 10, 11 form a conductor pair and are deflected by 90° within a deflection region 20 starting from a first straight portion 21, wherein a centre line 30, which runs exactly between the two signal conductors 10, 11, changes its direction within the deflection region 20. In the exemplary embodiment shown in FIG. 3, the direction change is continuous along a circular arc. Outside the deflection region 20, the centre line 30 is always straight. After the direction change, the conductor pair ends in another straight portion 21′.

[0085] In accordance with the invention, the centre line 30 transitions without a jump from the straight portions outside the deflection region 20 to the curved region inside the deflection region 20. Furthermore, in the first exemplary embodiment of FIG. 3, these transitions are also continuously differentiable, so that the tangent of the circular arc shape seamlessly transitions into the straight portions.

[0086] At their respective ends, the two signal conductors 10, 11 have an original distance d from each other. Within the deflection region 20, the two signal conductors 10, 11 are arranged closer to each other so that they have a reduced distance d.sub.r from each other there. Within transition regions 23, the distance between the signal conductors 10, 11 is reduced from the original distance d to the reduced distance d.sub.r.

[0087] Advantageously, the larger original distance d is thus present at non-critical points, which permits simpler manufacture and in particular simple electrical contacting of the signal conductors 10, 11. Within the deflection region 20, on the other hand, the reduced distance d.sub.r is used to reduce transit time differences and is preferably selected to be as narrow as the manufacturing processes allow without causing undesired deviations or even short circuits between the signal conductors 10, 11.

[0088] In the exemplary embodiment shown in FIG. 3, the signal conductors 10, 11 have a reduced width W.sub.r within the deflection region 20. The width of the signal conductors 10, 11 is reduced here in narrowing regions 22, which are identical to the transition regions 23 in the first example shown. This means that the width and the distance between the signal conductors 10, 11 are reduced at the same time.

[0089] FIG. 4 shows a plan view of a second embodiment of a conductor track arrangement 1 according to the invention. As in the first embodiment shown in FIG. 3, the conductor track arrangement 1 again comprises two signal conductors 10, 11 and a ground conductor 4, compare FIG. 1, which are arranged on the opposite side of a carrier 2, and therefore the ground conductor 4 is not visible in the representation in FIG. 4. As previously described in conjunction with the first embodiment of FIG. 3, the pair formed by the signal conductors 10, 11 is deflected by 90°. As in the first embodiment, a first straight portion 21 is followed by a first transition region 23 to the deflection region 20. The conductor pair leaves the deflection region 20 at a second transition region 23′ and ends in the second straight portion 21′.

[0090] In addition to the first embodiment of FIG. 3, a difference in the transit time of signals between the inner signal conductor 10 and the outer signal conductor 11 is not only reduced by the reduced distance d.sub.r within the deflection region 20. In the second embodiment of FIG. 4, a capacitor is additionally connected to the inner signal conductor 10 in the deflection region 20 and is configured here as a stub line 24 of length L.sub.L by way of example.

[0091] The stub 24 points inwards and in this example is rotated 45° to the direction of the centre lines 30 outside the deflection region 20, i.e. relative to the orientation of the straight portions. The stub 24 can also be attached to the inner signal conductor 10 at other locations within the deflection region 20. Depending on the space available, the stub 24 can also be placed at a different rotary angle.

[0092] By loading the inner signal conductor 10 with the electrical capacitance provided by the stub line 24, a propagation speed of an electrical signal in the inner signal conductor 10 is reduced compared to the outer signal conductor 11. In this case, the choice of the geometry of the stub 24, in particular the choice of the length L.sub.L, adjusts the capacitance in such a way that the reduced propagation speed of the signal compensates for the transit time difference caused by the deflection and not fully compensated for by the reduced distance d.sub.r.

[0093] In the embodiment of FIG. 4, the application of the capacitor to the inner signal conductor 10 is shown in combination with the reduction of the distance between the signal conductors 10, 11 and the width of the signal conductors 10, 11 in the deflection region 20. This has the advantage that only a smaller transit time difference has to be compensated for by the introduction of the electrical capacitance. However, it is of course possible to compensate for the signal transit times using the capacitor, in particular the stub 24, without reducing the distance and/or without reducing the width W of the signal conductors 10, 11.

[0094] FIG. 5 shows a plan view of a third embodiment of the conductor track arrangement 1. The third example corresponds to the second exemplary embodiment described with reference to FIG. 4, wherein the geometry of the stub 24 is different in this third example.

[0095] The stub 24 is provided here with a fan 25, which is electrically conductive and forms an electrical capacitance in particular in conjunction with the ground conductor 4 on the opposite side of the carrier 2.

[0096] By using a fan 25, as shown in FIG. 5, the length of the stub 24 required to reach a certain electrical capacitance can be reduced compared to the second example in FIG. 4. This makes it easier to comply with the criterion that the length of the stub 24 should be less than a quarter of the signal wavelength, especially when configuring the conductor track arrangement 1 for electrical signals with high frequencies. Furthermore, the spatial requirement of the stub 24 can be reduced, which simplifies the arrangement of the stub 24 on the carrier 2.

[0097] The graphs in FIGS. 6 to 8 show the phase difference, coupling factor and insertion loss for an example of a differential line according to the second embodiment shown in FIG. 4.

[0098] In this example, a 0.254 mm thick aluminium-nitride carrier was chosen as carrier 2. Conductive layers were applied and structured on both sides of the carrier using thin-film technology. Outside the deflection region, the distance d between the two signal conductors is 75 μm and the signal conductors each have a line width W of 91 μm. The reduced distance d.sub.r between the two signal conductors is 45 μm. The line width W is 57 μm, so that a differential impedance of 100 Ohm is obtained. This calculates the centre-to-centre distance P=102 μm and the path difference is ΔL=160 μm. If the path difference is not to be greater than λ/10 for low-distortion transmission, the signal frequency must not be greater than f.sub.max=63 GHz.

[0099] The capacitor attached to the inner signal conductor 10 in the form of the stub 24 reduces the speed of the signal in the inner signal conductor 10 compared to the speed in the outer signal conductor 11, so that the phase difference is further reduced. The graphs each show curves for different lengths L.sub.L of the stub 24, specifically 0 μm, 250 μm, 350 μm, 450 μm and 550 μm.

[0100] FIG. 6 shows the phase difference in ° between the two signal conductors against the frequency in GHz.

[0101] It can be seen here that the phase difference can be influenced by the choice of the length L.sub.L of the stub, wherein in the present example the phase difference becomes minimal for a length L.sub.L of 550 μm. At the frequency 30 GHz, the phase difference becomes zero in this example. The length difference is thus fully compensated for this case. Also over the entire frequency range up to 55 GHz, the phase difference is still clearly compensated compared to the example without stub, i.e. with a length L.sub.L of 0. In the frequency range of from 0 to 50 GHz, the phase difference remains below 10° and does not increase much even for higher frequencies.

[0102] FIG. 7 shows the coupling factor between differential-mode and common-mode waves in dB against frequency in GHz for a conductor track arrangement according to the second embodiment of FIG. 4.

[0103] The lower the coupling factor, the lower the phase difference. Accordingly, the lowest possible coupling factor is desirable. Again, the lowest coupling is achieved here for a stub length L.sub.L of 550 μm.

[0104] FIG. 8 shows the insertion loss in dB for the differential-mode wave against the frequency in GHz for a conductor track arrangement according to the second embodiment of FIG. 4.

[0105] The low insertion loss of the differential-mode wave, which can be seen in the graph in FIG. 8, shows that the differential-mode waves are only slightly disturbed by the stub on the inner signal conductor 1. Only from a frequency of 45 GHz does the insertion loss in the examples with a stub length greater than 0 deviate from the insertion loss without a stub. At 55 GHz the additional loss is approx. 1 dB.

[0106] For all examples, the increase is moderate in the examined frequency range up to 50 GHz and only has a significant effect at frequencies above 50 GHz. In this example, a length L.sub.L of the stub of 550 μm would thus achieve the best reduction of the transit time differences with only low insertion loss.

[0107] FIG. 9 shows a base 100 for an electronic element comprising one of the conductor track arrangements 1 according to the invention.

[0108] The base 100 is made of a metal, for example, and has a through-opening 102, through which two electrical conductors in the form of pins 106 are passed in the example of FIG. 9. The pins 106 are held in place by a fixing material 104, which is electrically insulating and closes the through-opening 102. The fixing material 104 is, for example, a glass or a glass ceramic.

[0109] On a surface of the base 100, in the vicinity of the through-opening 102, there is a platform 110 on which the carrier 2 of the conductor track arrangement 1 is mounted. In particular, a ground conductor 4 arranged on the underside of the carrier 2, which is not visible in FIG. 9, can be electrically connected to the platform 110 and the base 100 so that these parts are all at ground potential.

[0110] As can be seen from FIG. 9, the signal conductors 10, 11 of the conductor track arrangement 1 are formed and arranged at a first end in such a way that they are directly opposite and preferably directly adjacent to the pins 106. In this way, an electrical connection between the pins 106 and the signal conductors 10, 11 can be easily established via a solder joint 108.

[0111] At their other end, the signal conductors 10, 11 are arranged and formed to provide a contact point 130 for contacting an electronic element (not shown). Such an electronic element can be, for example, a laser diode or a photodiode. With reference to a centre line 30, compare FIGS. 3 to 5, the pair of signal conductors 10, 11, starting from the first end facing the pins 106, initially runs straight and then reaches a deflection region 20, compare FIGS. 3 to 5, in which the direction is deflected by 90°, and then runs straight again to the second end. The conductor track arrangement 1 shown in the example of FIG. 9 corresponds to the third embodiment of the conductor track arrangement 1 already described with reference to FIG. 5. Accordingly, the conductor track arrangement 1 has a stub 24 with a fan 25, which serves as a capacitor and reduces the signal propagation speed in the inner signal conductor 10 within the deflection region 20. This compensates for part of a transit time difference that remains in the deflection region 20 even after the distance between the two signal conductors 10, 11 has been reduced.

[0112] FIG. 10 shows another example of a base 100 for an electronic element. As already described with reference to FIG. 9, the base has a carrier 2, arranged on a platform 110, with a conductor track arrangement 1. The conductor track arrangement 1 placed on the platform 110 is similar to the second variant of the conductor track arrangement 1 described with reference to FIG. 4, but has additional ground planes 120 which cover free regions of the carrier 2 at a distance from the signal conductors 10, 11. Through-platings 122, also called vias, are provided for contacting the ground planes 120 with the ground potential of the base 100 or the platform 110. The ground planes 120 serve as additional shielding of the differential line formed by the signal conductors 10, 11 and the ground conductor 4, which is not visible in FIG. 10.

[0113] Although the present invention has been described with reference to preferred exemplary embodiments, it is not limited thereto, but can be modified in a variety of ways.

LIST OF REFERENCE SIGNS

[0114]

TABLE-US-00001  1 conductor track arrangement U.sub.diff differential voltage between signal conductors  2 carrier U.sub.1 voltage between inner and ground conductors  4 ground conductor U.sub.2 voltage between outer and ground conductors 10 (inner) signal conductor d distance between inner and outer conductors 11 (outer) signal conductor d.sub.r distance between inner and outer conductors 20 deflection region D distance between ground and signal conductors 21 straight portion W width of signal conductor 21′ second straight portion W.sub.r reduced width of signal conductor 22 narrowing region R.sub.1 radius of curvature of inner signal conductor 22′ second narrowing region R.sub.2 radius of curvature of outer signal conductor 23 transition region P difference between the radii of curvature 23′ second transition region L.sub.L length of the stub 24 stub 100 base 25 fan 102 opening 30 centre line 104 fixing material 106 pin 108 solder point