The invention relates in general to a high frequency circuit module, and in particular, to ground layers in a high frequency circuit module.
As technology advances, mobile telecommunication devices continue to shrink in scale and increase in circuit density. Consequently leakage current is a significant issue. To resolve the leakage current issue high dielectric material is utilized as a circuit substrate. This complicates high frequency circuit design.
Moreover, an even thinner line width of the stripline has to be employed to maintain the original impedance, but the minimum line width is limited by current technology.
A multi-layer high dielectric constant substrate is commonly used to further enhance circuit density, but the substrate has severer parasitical capacitance effect.
Multi-layer circuit structures require more field shielding ground layers. The result has a severer parasitical capacitance effect, and degrade the performance of the high frequency circuit modules. To counter the parasitical capacitance issue, the line width of striplines may be reduced. Unfortunately the minimum line width is limited by current technology.
The invention is directed to a circuit module with less parasitical capacitance.
According to one embodiment of the invention, a circuit module with less parasitical capacitance is provided. The circuit module comprises at least one first circuit structure, at least one second circuit structure, at least one block layer, at least one first ground layer, and at least one second ground layer. The first circuit structure is disposed in at least one first substrate. The second circuit structure is disposed in at least one second substrate. The first substrate and the second substrate form a stacked substrate. One side of the block layer contacts with the stacked substrate. The first ground layer is between the first circuit structure and the second circuit structure. And the second ground layer is on another side of the block layer, and is electrically coupled to the first ground layer.
In another embodiment of the invention, a circuit module contacting one side of an external system is described. The circuit module comprises at least one first circuit structure, at least one second circuit structure, at least one block layer, and at least one first ground layer. The first circuit structure is disposed in at least one first substrate. The second circuit structure is disposed in at least one second substrate. The first substrate and the second substrate form a stacked substrate. One side of the stacked substrate contacts with the side of the external system. The first ground layer is between the first circuit structure and the second circuit structure. The first ground layer is electrically coupled to a second ground layer which on another side of the external system. The dielectric constant of the external system is lower than those of the first circuit structure and the second circuit structure.
The invention will become more fully understood from the detailed description, given hereinbelow, and the accompanying drawings. The drawings and description are provided for purposes of illustration only and, thus, are not intended to be limiting of the present invention.
Referring now to
The circuit region 402 is formed by stacked substrates 420, and comprises at least one circuit structure 410, 412, and at least one ground layer 406. The material of the substrate 420 may be a low dielectric material (low-k dielectrics), ceramic material, organic polymer material, silicon material or a high dielectric material (high-k dielectrics). The ground layer 406 is disposed between the circuit structures 410 and 412, which may be a digital circuit structures, a high-power circuit structures, a low-power circuit structures, an analog circuit structures, or a stripline circuit structures. Furthermore, the elements 422a and 422b are formed on circuit region 402 and electrically coupled with the circuit structure 410. The elements 422a and 422b may be resistor, capacitor, inductor, microprocessor, controller, or other un-embedded elements.
One side of the block layer 404 is contacted with one side of the top or bottom substrate 420 of the circuit region 402, and another side of the block layer 404 has a ground layer 408 and connection pads 414 and 416. The dielectric constant of the block layer 404 is lower than that of the top or bottom substrate 420, and may be any low dielectric material, ceramic material, high molecular material, silicon material or high dielectric material.
The ground layer 408 is coupled to the ground layer 406 through at least one connecting segment 418, thus the ground layer 408 is extended to at least one region which doesn't has the circuit structures in circuit region 402, thereby the dimension of the effective ground layer will increase without increasing that of communication circuit module 400. Consequently, the ground layer 408 can be an electromagnetic shield between the circuit structures 410 and 412 by the ground layer 406, and prevent the interference between the circuit structures 410 and 412. The material of ground layers 406 and 408 may be metal, carbon fiber or other conductive material.
The circuit structures 410 and 412 are electrically coupled to the external system by the connection pads 414 and 416.
The surface of the external system 500 comprises a circuit structure 502a and a ground layer 502b, both disposed on the same or different surfaces of the external system 500. The external system 500 may be a printed circuit board.
The circuit structures 410 and 412 of the communication module 400a are coupled to the circuit structure 502a of external system 500 by connecting segment 418b, connection pads 418c and 504b, or connecting to the external system 500 and fixed by the connection pads. Ground layer 406 of the communication circuit module 400a is coupled to the ground layer 502b of the external system 500 through connecting segments 418 and 418a, to provide a complete ground layer. Connection between the ground layers 406 and 502b may be accomplished by connecting segments 418 and 418a directly, coupling connection pads 418c and 504a electrically, or connecting segment 418a penetrating ground layer 502b and secured by connection pad 504.
In this embodiment, some part of the ground layer is on the external system, and the block layer of the circuit module has a lower dielectric constant than that of the external system, resulting in reduced parasitical capacitance between the modules, and reduced a dimension of the circuit module.
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Number | Date | Country | Kind |
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94121368 | Jun 2005 | TW | national |