Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-03-17
2001-11-20
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S846000
Reexamination Certificate
active
06320543
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microwave and millimeter wave circuit apparatus used as a high-frequency module for a communication apparatus, radar, or the like and in more particular, to a microwave and millimeter wave circuit apparatus capable of reducing a transmission loss.
2. Description of the Related Art
In order to reduce the size of the microwave and millimeter wave circuit apparatus and perform mass production thereof, it is effective to prepare transmitter and receiver circuits of the microwave and millimeter wave as a multi-chip module (MCM) and make this transmitter and receiver circuits, which is the multi-chip module, as an integration block with an antenna.
FIG. 7
schematically shows a microwave and millimeter wave circuit apparatus conventionally suggested as an integration module having an antenna.
In this conventional microwave and millimeter wave circuit apparatus, a metal case package
71
contains a monolithic microwave integrated circuit (MMIC)
72
and an antenna substrate
73
which are connected to each other by a bonding wire
74
. Moreover, an intermediate frequency (IF) terminal
75
and a bias terminal
76
are connected to the MMIC
72
via a bonding wire
74
. Moreover, an attempt has been made to prepare a microwave and millimeter wave circuit apparatus using a GaAs substrate.
FIG. 8
schematically shows a conventional microwave and millimeter wave circuit apparatus using a GaAs substrate.
An MMIC substrate
81
has a receiver integrated circuit
81
a
formed on the GaAs substrate. Moreover, in an antenna substrate
82
, a patch antenna
85
is provided on a quartz substrate. On the surface of the antenna substrate
82
, a grounding metal cover
83
and a coupling slot
84
are formed. The MMIC substrate
81
and the antenna substrate
82
are bonded to each other, so that the circuit in the MMIC substrate
81
and the antenna
85
are connected to each other via the coupling slot
84
.
However, in the conventional microwave and millimeter wave circuit apparatus shown in
FIG. 7
, the MMIC
72
and the antenna substrate
73
are only connected to each other only the wire bonding
74
and are contained in the package
71
in an airtight way. Accordingly, there is a limit to reduction in size and mass production. Especially in the millimeter wave circuit, there is a problem that because of parasitic elements such as inductance caused by the wire bonding
74
, it is difficult to perform connections with a low loss and to assure performance repeatability. Furthermore, the patch antenna is connected to the RF circuit such as the MMIC on a plane-to-plane basis and a long feed line to the patch antenna is required. It is necessary to reduce the loss in the feed line. Moreover, in the conventional microwave and millimeter wave circuit apparatus shown in
FIG. 8
, there is a problem that it is necessary to accurately position the MMIC substrate
81
and the antenna substrate
82
, complicating the assembling process. Furthermore, since circuit elements are provided on the upper and the lower surface of the apparatus, there is a problem that when mounted on a stage it is impossible to measure microwave and millimeter wave characteristics using a probe apparatus or the like.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a microwave and millimeter wave circuit apparatus which can easily be produced and is capable of reducing the entire size and improving productivity.
The microwave and millimeter wave circuit apparatus according to the present invention comprises: grounding conductive layer grounded; a first dielectric layer formed on the grounding conductive layer; a signal line formed selectively on the first dielectric layer; a second dielectric layer covering at least a part of the signal line; a cavity formed in this second dielectric layer and extending to the signal line; a monolithic microwave integrated circuit arranged in the cavity and connected to the signal line; and an antenna connected to the signal line.
In the present invention, the microwave and millimeter wave circuit apparatus may further comprise two second grounding conductive layers formed so as to sandwich the signal line on the first dielectric layer and grounded, wherein the signal line and the two grounding conductive layer constitute a coplanar line.
Moreover, the first dielectric layer may have a thickness smaller than a value obtained by c/(4f·(∈r
1
−1)
½
) wherein ∈r
1
is a relative dielectric constant of the first dielectric layer, f is a frequency of the signal propagating in the signal line, and c is a light velocity, and the second dielectric layer may have a thickness smaller than a value obtained by c/(4f·(∈r
2
−1)
½
) wherein ∈r
2
is a relative dielectric constant of the second dielectric layer, f is a frequency of the signal propagating in the signal line, and c is a light velocity.
Moreover, the monolithic microwave integrated circuit may be flip-chip mounted. Furthermore, a groove may be formed in the first dielectric layer, and the first dielectric layer in the region of the groove may have a thickness smaller than a value obtained from equation c/(4f(∈r
1
−1)
½
) wherein ∈r
1
is a relative dielectric constant of the first dielectric layer, f is the maximum frequency of the signal propagating in the signal line, and c is the light velocity.
Furthermore, a second groove may be formed in the second dielectric layer, and the second dielectric layer in the region of the second groove may have a thickness smaller than a value obtained from equation c/(4f(∈r
2
−1)
½
) wherein ∈r
2
is a relative dielectric constant of the second dielectric layer, f is the maximum frequency of the signal propagating in the signal line, and c is the light velocity.
Moreover, the microwave and millimeter wave circuit apparatus may further comprise a via hole buried in the first dielectric layer and connected to the grounding conductive layer and to the second grounding conductive layer.
Furthermore, the second dielectric layer may have at least a portion where no metal cover is provided. The microwave and millimeter wave circuit apparatus may further comprise: a surface conductive layer formed on the second dielectric layer; and a second via hole buried in the second dielectric layer and connected to the second grounding conductive layer and the surface conductive layer.
Moreover, in a cross section orthogonally intersecting the extension of the signal line, the second grounding conductive layer may be formed inside of the ends of the first and the second dielectric layers.
Furthermore, the signal line may have a region exposed from the first or the second dielectric layer between the cavity and the antenna.
REFERENCES:
patent: 5903239 (1999-05-01), Takahashi et al.
patent: 6018299 (2000-01-01), Eberhardt
Ito Masaharu
Maruhashi Kenichi
Ohata Keiichi
Hutchins, Wheeler & Dittmar
Le Hoang-anh
NEC Corporation
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