KR20150044788A - Low Power, High Speed Multi-Channel Chip-to-Chip Interface using Dielectric Waveguide - Google Patents

Abstract

Disclosed is an electrical fiber for board-to-board connection between transmitter I/O or receiver I/O. The electrical fiber includes a dielectric waveguide for propagating a signal to a board of a receiver side from a board of a transmitter side, and a metal cladding which wraps up the dielectric waveguide.

Description

[0001] The present invention relates to a chip-to-chip interface using a low-power, high-speed multi-channel dielectric waveguide,

Embodiments of the present invention relate to a chip-to-chip interface using a low-power, high-speed multi-channel dielectric waveguide.

Demand for bandwidth is increasing in wired communications, which requires high speed, low power, and low cost I / O. In conventional copper interconnects, attenuation due to skin effects, etc., limits system performance. In order to preserve the losses in the existing copper interconnects, penalties in terms of power, cost, etc. are applied, and this penalty exponentially increases as the data rate or transmission distance increases.

A new chip-to-chip interface using a dielectric for transport channels is proposed to solve the above-mentioned problems.

Electrical fibers for board-to-board interconnections between transmitter I / O or receiver I / O include a dielectric waveguide for propagating signals from the transmitter side board to the receiver side board; And a metal cladding for wrapping up the dielectric waveguide.

At least one of both ends of the dielectric waveguide may be tapered for impedance matching between the dielectric waveguide and the microstrip circuit.

At least one of both ends of the dielectric waveguide can be linearly shaped to optimize the impedance of the dielectric waveguide with the highest power transfer efficiency.

The metal cladding may include copper cladding.

Both ends of the dielectric waveguide can be vertically coupled to the transmitter side board and the receiver side board.

The proportion of the length of the metal cladding to the length of the dielectric waveguide can be designed based on the length of the electrical fiber.

The metal cladding may be finished with the dielectric waveguide in a predetermined form.

A board-to-board interconnect device having an electrical fiber transmits signals from a transmitter side board to a receiver side board, comprising: an electrical fiber having a metal cladding; And a microstrip circuit coupled to the electrical fiber and having a microstrip-to-wave guide transition (MWT).

At least one of both ends of the electrical fiber can be tapered for impedance matching between the electrical fiber and the microstrip circuit in the interconnect device.

At least one of both ends of the electrical fiber can be linearly shaped to optimize the impedance of the electrical fiber with the highest power transfer efficiency.

The metal cladding may include copper cladding.

The interconnecting device may further comprise a board-to-fiber connector for vertically connecting the electrical fiber to at least one of the transmitter side board and the receiver side board.

The proportion of the length of the metal cladding to the length of the electrical fiber can be designed based on the length of the electrical fiber.

The interconnecting device comprising: a microstrip feeding line for feeding the signal from the first layer to the microstrip circuit; A slotted ground plane including a slot for minimizing the ratio of the reverse traveling wave to the forward traveling wave in the second layer; A ground plane comprising an array of vias for forming an electrical connection between the slotted ground plane and the ground plane in a third layer; And a patch for emitting the signal at a resonant frequency.

The metal cladding may be finished with the dielectric waveguide in a predetermined form.

의 아이(eye) 다이어그램에 대한 시뮬레이션된 결과를 나타낸 그래프이다.1 is a diagram illustrating a structure of a chip-to-chip interface according to an embodiment of the present invention.
Figure 2a schematically illustrates a model interconnected with a two-port network in accordance with an embodiment of the present invention.
FIG. 2B is a diagram for explaining a relationship between waves reflected from each transition and transmitted waves according to an embodiment of the present invention.
Figures 3a-d are graphs illustrating analytical estimates and simulated results for S parameters in a structure interconnected according to one embodiment of the present invention.
4A-4D are graphs illustrating analytical estimates and simulated results for S parameters in a structure interconnected according to one embodiment of the present invention.
5 is a graph illustrating analytical estimation and simulated results for group delay in a structure interconnected according to an embodiment of the present invention.
Figure 6 shows a side view of a microstrip transition constructed in accordance with one embodiment of the present invention.
7 illustrates a front view of a microstrip transition constructed in accordance with one embodiment of the present invention.
8 illustrates an exploded view of a microstrip-wave guide transition constructed in accordance with one embodiment of the present invention.
9 is a view showing different lengths of an electrical fiber and a tapered waveguide having a metal cladding constructed according to an embodiment of the present invention.
10 illustrates a board-to-wave guide connector constructed in accordance with an embodiment of the present invention.
11 is a graph showing simulated results for S parameters in an interconnect configured in accordance with an embodiment of the present invention
Figure 12 shows a schematic diagram of a PAM4 28Gbps PRBS < RTI ID = 0.0 >

FIG. 5 is a graph showing simulated results of an eye diagram of an embodiment of the present invention. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following, although limited embodiments are described, these embodiments are examples of the present invention and those skilled in the art can easily modify these embodiments.

Embodiments of the present invention may provide improved interconnects instead of electrical wired lines. For example, an electrical fiber, referred to as a new type of dielectric waveguide, can replace an existing copper line. Such an electrical fiber can be defined as a dielectric waveguide having a metal cladding.

Dielectrics with frequency independent attenuation characteristics enable high data rates to be achieved without any additional receiver stage compensation, or even with very little receiver stage compensation. Parallel channel data transmission may be possible through a vertical combination of electrical fiber and PCB. PCBs with electrical fibers for board-to-board interconnections between transceiver I / O can be defined as board-to-board interconnect devices. For example, such interconnecting devices may include electrical fibers, a transmission stage board, a receiving stage board, a board-to-fiber connector, a microstrip feeding line, a slotted ground plane, a ground plane and a patch. At this time, the interconnecting device may further include vias connecting the two ground planes to one another.

The new board-to-fiber connectors are provided to securely secure multiple electrical fibers to the PCB and maximize space (area) efficiency by bringing each other as close as possible. Physically, the flexible nature of the electrical fiber can support connecting any terminations at any location in free space. The metal cladding of the electrical fiber can keep the overall transceiver power consumption constant regardless of the length of the electrical fiber. Cladding can also isolate interference of signals in other channels and adjacent electrical fibers. Here, the interference can be a cause of band-limiting problems.

Slot-coupled patch-type microstrip-to-wave guide transitions can minimize reflection between the microstrip and the waveguide. A microstrip-to-wave guide transition transmits a microstrip signal as a waveguide signal, which can have the advantage of low cost. This is because it can be manufactured through a general PCB manufacturing process.

1 is a diagram illustrating a structure of a chip-to-chip interface according to an embodiment of the present invention.

Referring to FIG. 1, an interconnect according to an embodiment of the present invention may be shown in FIG. 1 illustrates an electrical fiber 101 used as a board-to-board interconnect. The input signal comes from the output of a 50 ohm matched transmitter die 102 and is propagated along transmission line 103 and the microstrip-to-wave guide transition 104 (MWT) on the transmitter side board receives the microstrip signal To the waveguide signal. The wave, e.g., a waveguide signal, may be transmitted along the electrical fiber 101, which may be converted to a microstrip signal at the MWT 105 on the receiver side board. Similarly, the signal may be transmitted along the transmission line 106 and may proceed to a 50 ohm matched receiver input 107. Here, the dielectric waveguide can transmit a signal from the transmitter side board to the receiver side board.

Figure 2a schematically illustrates a model interconnected with a two-port network in accordance with an embodiment of the present invention. FIG. 2B is a diagram for explaining a relationship between waves reflected from each transition and transmitted waves according to an embodiment of the present invention.

At each end of the electrical fiber, the impedance discontinuity can reduce energy transfer efficiency from the transmission line to the waveguide and / or energy transfer efficiency from the waveguide to the transmission line. To interpret the effect of this discontinuity, the overall interconnections can be considered as a simple two-port network as shown in FIG. 2, which can be modeled through Equations 1-3.

 [Equation 1]

&Quot; (2) "

&Quot; (3) "

와

로 표현될 수 있다. 그리고, 반사된 웨이브들은

와

로 표현될 수 있다. 유사하게, 웨이브가이드로부터 전송 선로로의 트랜지션에서, 웨이브가이드 측 및 전송 선로 측에서의 입력 웨이브들 각각은

와

로 표현될 수 있다. 그리고, 반사된 웨이브들은

와

로 표현될 수 있다. 이러한 간략화된 모델로부터, 반사된 웨이브들 및 전송된 웨이브들 사이의 관계식은 다음을 가정한다. 전송 선로로부터 웨이브가이드로의 트랜지션에서 복소 반사 계수는

이고, 복소 전송 계수는

이다. 그리고, 웨이브가이드로부터 전송 선로로의 트랜지션에서 복소 반사 계수는

이고, 복수 전송 계수는

이다.In the transition from the transmission line to the waveguide, each of the input waves at the transmission line and the waveguide side

Wow

. ≪ / RTI > Then, the reflected waves

Wow

. ≪ / RTI > Similarly, in the transition from the waveguide to the transmission line, each of the input waves at the waveguide side and the transmission line side

Wow

. ≪ / RTI > Then, the reflected waves

Wow

. ≪ / RTI > From this simplified model, the relationship between reflected waves and transmitted waves assumes the following. The complex reflection coefficient at the transition from the transmission line to the waveguide is

, And the complex transmission coefficient is

to be. Then, in the transition from the waveguide to the transmission line, the complex reflection coefficient is

, And the plurality of transmission coefficients is

to be.

The following equations may represent a scattering matrix (e.g., S-parameters) for the overall interconnect.

 &Quot; (4) "

&Quot; (5) "

&Quot; (6) "

&Quot; (7) "

&Quot; (8) "

Figures 3a-d are graphs illustrating analytical estimates and simulated results for S parameters in a structure interconnected according to one embodiment of the present invention. 4A-4D are graphs illustrating analytical estimates and simulated results for S parameters in a structure interconnected according to one embodiment of the present invention. 5 is a graph illustrating analytical estimation and simulated results for group delay in a structure interconnected according to an embodiment of the present invention.

3, 4, and 5 are graphs illustrating analytical estimation results for S parameters in an overall interconnect constructed in accordance with an embodiment of the present invention. For example, FIGS. 3, 4, and 5 may be plotted in Equations 5 through 8 and may be representative of results for different cases of waveguide lengths (e.g., 5 cm, 10 cm) . Each result can be compared with the simulation results derived from the three-dimensional electromagnetic simulation tool (Ansys, HFSS).

Figures 3, 4 and 5 may mean that there is a waveguide-length-dependent oscillation in the results for S parameters and group delay for the overall interconnect. The longer the waveguide, the more severe the impact of such vibration. If an eye diagram is used as a metric for the evaluation of such a transmission system, such vibrations can create serious problems in eye opening and zero crossing, and even become a major cause of increasing bit error rate (BER) .

The vibrations present in the results for the S parameters and the group delay may be due to the following facts. A reflected wave that occurs in an impedance discontinuity undergoes some attenuation along the propagation, which can create a phenomenon similar to what happens in a cavity resonator. These waves can scatter back and forth within the electrical fiber, and solidify the standing wave.

Strategies to address these problems may include:

First, making the reflection coefficient r2 as small as possible,

Second, to ensure a relatively small level of channel loss while making accurate attenuation along the electrical fiber.

Third, to construct a waveguide using materials with low permittivity

These strategies can be verified by the above equations (5) to (8). Thus, according to one embodiment of the present invention, the MWT is used for the purpose of creating a lower reflection coefficient r2.

Figure 6 shows a side view of a microstrip transition constructed in accordance with one embodiment of the present invention. 7 illustrates a front view of a microstrip transition constructed in accordance with one embodiment of the present invention.

FIG. 6 shows a side view of the MWT, and FIG. 7 shows a front view of the MWT. Electrical fibers 604 and 704 having metal cladding 601 and 701 may be connected to the microstrip circuit and may be connected to the patch elements 603 and 703 disposed on the board. Here, the metal cladding 601, 701 can close the dielectric waveguides 602, 702. For example, the metal cladding 601, 701 may include a copper cladding, and the patch elements 603, 703 may comprise a microstrip line. The patch elements 603 and 703 can emit a signal at a resonant frequency.

According to one embodiment of the present invention, the metal cladding 601, 701 can finish the dielectric waveguides 602, 702 in a predetermined form. For example, a predetermined form of the metal cladding 601, 701 may expose a stop of the dielectric waveguide 602, 702 and another form of the metal cladding 601, 701 may expose a particular portion of the dielectric waveguide 602, May be punctured. In addition, the predetermined shapes of the metal cladding 601, 701 may vary.

8 illustrates an exploded view of a microstrip-wave guide transition constructed in accordance with one embodiment of the present invention.

8 shows the detailed structure of each layer of the board. The board can be fabricated in a three-layer structure. The microstrip feeding line 801 can be located in the first layer and the slotted ground plane 802 punctured by an aperture can be disposed in the second layer. The patch element 803 and the ground plane 804 may be disposed in the third layer. For example, the microstrip feeding line 801 may feed the signal to the microstrip circuit in the first layer, and the slotted ground plane 802 may be used to minimize the ratio of the reverse traveling wave to the forward traveling wave in the second layer Slots. The ground plane, including the via 807, forms an electrical connection between the grounded ground plane 802 and the ground plane 804 in the third layer. Here, the vias 807 may be arranged in an array.

의 크기와

의 두께를 갖는다. 제2 레이어와 제3 레이어 사이의 다른 코어 기판 806은 로저스(Rogers) 사의 RO3010 Prepreg로 구성될 수 있으며, 이것은

의 크기와

의 두께를 갖는다.The substrate 805 between the first layer and the second layer may be composed of CER-10 from Taconic. Here, the CER-10

The size of

. Another core substrate 806 between the second and third layers can be configured with RO3010 Prepreg from Rogers,

The size of

.

The vias 807 serve to make an electrical connection between the second ground plane and the third ground plane. The microstrip width, substrate thickness, slot size, patch size, via diameter, spacing between vias, waveguide size, and waveguide material can be optimized for a specific resonant frequency of the microstrip circuit And may be changed depending on the mode of the wave, which is obvious to those skilled in the art.

의 크기를 갖는 ECCOSTOCK PP (Laird TECHNOLOGIES.)는 60GHz 대역 신호를 MWT에서 최소의 반사를 가지고 통과시키기 위하여 사용될 수 있다. 웨이브가이드의 교차면의 사이즈가 커질수록 전파할 수 있는TE/TM 모드의 수가 증가할 수 있다. 그리고, 그것은 트랜지션의 삽입 손실에서 개선을 가져올 수 있다.In particular, the size of the slot and aperture can be an important factor in signal transmission and reflection. The size of the slot and opening surface can be optimized to minimize the ratio of the backward traveling wave to the forward traveling wave by iterative simulation. The cut-off frequency and impedance of the waveguide can be determined by the size of the intersecting surface and the type of material used. In the present invention,

ECCOSTOCK PP (Laird TECHNOLOGIES.) Can be used to pass a 60 GHz band signal with minimal reflection in MWT. The larger the size of the intersection of the waveguide, the larger the number of TE / TM modes that can propagate. And, it can lead to an improvement in insertion loss of transitions.

Figure 9 is a view showing different lengths of an electrical fiber and a tapered waveguide having a metal cladding constructed in accordance with an embodiment of the present invention.

In order to reduce the effect of vibration in the result of the S-parameter, it may be used to minimize the reflection occurring in the MWT, as well as to take an optimized attenuation along the electrical fibers 901, 902, 903. This strategy can be implemented by shortening the length of the metal cladding finishing the dielectric waveguide of the electrical fibers 901, 902, 903 at each end. Metal gliding can completely limit the electromagnetic wave that prevents the radiation loss of energy. For this reason, utilizing short metal cladding can result in large radiation losses. This type of energy loss can be considered as a damping along the electrical fibers 901, 902, 903, which can have a significant impact on vibration in the result of the S-parameter.

In addition, the dielectric loss can be considered as the attenuation along the electrical fibers 901, 902, 903. It can be attributed to the tangent loss of the dielectric waveguide and can be related to the length of the waveguide. Dielectric losses consumed along the long waveguide can reduce the effect of vibration.

Thus, a long dielectric fiber 903 can have a greater proportionality of metal cladding than a short electrical fiber 901 when considering the same channel loss. One end of the electrical fiber 904 may exhibit an isometric projection of a tapered waveguide. Impedance matching may be possible between the dielectrics used for the dielectric waveguide and the microstrip circuit on the board. For example, the proportionality of the length of the metal cladding in the length of the dielectric waveguide can be designed based on the length of the electrical fibers 901, 902, 903.

Further, based on the fact that the size of the waveguide determines its impedance, linearly shaping at least one of the two ends of the dielectric waveguide may be efficient in finding an optimal impedance. That is, at least one of both ends of the dielectric waveguide may be tapered (tapered) for impedance matching between the dielectric waveguide and the microstrip circuit. For example, at least one of both ends of the dielectric waveguide can be linearly shaped to optimize the impedance of the dielectric waveguide with the highest power transfer efficiency.

According to one embodiment of the present invention, a board-to-board interconnect using electrical fibers 901. 902. 903 includes an electrical fiber 901 with metal cladding for transmitting signals from a transmitter side board to a receiver side board, 902, and 903 and a microstrip circuit that contacts them.

10 illustrates a board-to-wave guide connector constructed in accordance with an embodiment of the present invention.

FIG. 10 shows an isometric view of the board-to-fiber connector 1001. The electrical fibers are firmly secured to the board with a board-to-fiber connector 1001. The connector bridges 1002 and 1003 can be inserted into holes drilled in the board to secure the board-to-fiber connector 1001 to the board. For example, through the board-to-fiber connector 1001, the electrical fibers can be vertically connected to at least one of the transmitter side board or the receiver side board

In addition, there may be an array of transition devices 1004, 1005, 1006 in the connector for physical fixation of the electrical fibers. With such a connector, the electrical fiber can be connected to the microstrip circuit of the board. Such a manner of vertically connecting both ends of the dielectric waveguide to the transmitter side and the receiver side board is an effective way to reduce the area required for coupling, which is well illustrated in FIG. Because of this configuration, a large number of electrical fibers can be used to simultaneously connect a plurality of channels for a parallel system with broadband. For example, the dielectric waveguide may be vertically coupled to at least one of the transmitter side board and the receiver side board.

11 is a graph showing simulated results for S parameters in an interconnect configured in accordance with an embodiment of the present invention

Referring to FIG. 11, the S-parameter simulation results of the overall interconnect configured in accordance with an embodiment of the present invention are shown graphically. For example, the result can be achieved using a 50 cm electrical fiber. The bandwidth that satisfies the 10dB return loss is from 54GHz to 79GHz at 15GHz. The insertion loss on the pass band can be less than 15dB, and the insertion loss is constant in the wide band.

의 아이(eye) 다이어그램 시뮬레이션 결과를 나타낸 그래프이다.Figure 12 shows a PAM4 28Gbps PRBS < RTI ID = 0.0 >

FIG. 7 is a graph showing the eye diagram simulation result of FIG.

의 아이(eye) 다이어그램을 보여줄 수 있다. 아이 다이어그램은 복조된 데이터 패턴을 나타낼 수 있으며, 복조된 데이터 패턴은 65GHz 캐리어로 변조되고, 본 발명의 일실시예에 따라 구성된 상호 연결의 채널을 통하여 통과한 것일 수 있다.To evaluate the performance of the overall interconnect, Figure 12 shows PAM4 28Gbps PRBS

Eye diagram of the user. The eye diagram may represent a demodulated data pattern and the demodulated data pattern may be modulated with a 65 GHz carrier and passed through a channel of the interconnect configured in accordance with an embodiment of the present invention.

Electrical fibers can suggest new ways to enable high-speed data communications. The MWT structure can transit a wideband signal with minimal reflection at discontinuity. Metal cladding that terminates the dielectric waveguide can reduce radiation losses and can be effective in reducing channel loss.

In addition, if the center frequency can move to a higher frequency band, a wider bandwidth can be achieved without paying any additional complexity or cost. Thus, the electrical fiber can provide a solution to an I / O channel that has a demand to transmit data at a very high speed. In particular, electrical fibers can replace all copper wire lines at the 100 Gbps backplane interface, which is based on the IEEE 802.3 bj KR standard. It can also be applied to the IEEE 802.3 bj SR standard with an extended transmission distance. The board-to-board interface can employ electrical fiber as a promising solution in the data center market.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (1)

An electrical fiber for board-to-board interconnection between a transmitter I / O or a receiver I / O,
A dielectric waveguide for propagating a signal from the transmitter side board to the receiver side board; And
A metal cladding for wrapping up the dielectric waveguide,
≪ / RTI >

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