Telecommunications – Transmitter and receiver at same station – With a common signal processing stage
Reexamination Certificate
1998-03-20
2001-07-17
Bost, Dwayne D. (Department: 2744)
Telecommunications
Transmitter and receiver at same station
With a common signal processing stage
C455S084000, C455S090300, C455S073000
Reexamination Certificate
active
06263193
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microwave transmitter/receiver module that operates in microwave frequency bands involving centimeter waves and millimeter waves.
2. Description of the Related Art
FIGS. 1A and 1B
are a perspective view and a block diagram showing a microwave transmitter module according to a prior art operating in microwave bands around 10 GHz or over including sub-millimeter and millimeter bands.
The module has a semiconductor chip
71
a
serving as an oscillator (OSC), a semiconductor chip
71
b
serving as a modulator (MOD), and a semiconductor chip
71
c
serving as a power amplifier (PA). Each of the chips has a square shape of about 2 mm×2 mm. The chips
71
a
to
71
c
are housed in separate chambers and are shielded by a package
75
from external electromagnetic fields. The chips
71
a
to
71
c
are connected to one another through microwave transmission lines such as coaxial lines and microstrip lines.
This kind of structure is employed not only for transmitter modules but also for receiver modules having low-noise high-frequency amplifiers (LNAs) and demodulators.
Accommodating the chips
71
a
to
71
c
in three separate chambers as shown in
FIG. 1A
complicates the structure of the package. It is preferable to package all of the chips
71
a
to
71
b
in a single chamber and shield them from external electromagnetic fields. The package with a single chamber to accommodate and shield all chips, however, unavoidably has a large space to easily cause a cavity resonance.
To solve the problem of cavity resonance, the applicant of the present invention has proposed a microwave transmitter/receiver (T/R) module in Japanese Patent Application No. 8-180846. This module is shown in
FIGS. 2A and 2B
. The module has a single closed space that contains transmitter and receiver antenna patterns, etc., to provide functions necessary for microwave communication. The closed space has a narrowed space
90
.
A semiconductor chip
85
is mounted on a circuit board
82
, which is housed in a housing
84
made of a conductor. I/O terminals
88
electrically connecting between the chip
85
and the outside are arranged on side walls at central part of the housing
84
where the narrowed space
90
is present. The housing
84
is covered with a lid
81
. A conductor layer
86
is formed at central part of the bottom surface of the lid
81
. The narrowed space
90
is an electromagnetically narrowed space defined by three conductor planes consisting of the bottom and two side faces of the narrowed space
90
and one plane consisting of the conductor layer
86
at bottom of the lid
81
. The board
82
further has receiver antenna patterns
83
, transmitter antenna patterns
87
, and feeders
89
b
and
89
a
for connecting the antenna patterns
83
and
87
to the chip
85
.
FIG. 2B
is a sectional view taken along a line III—III of
FIG. 2A
, showing part of the board
82
. The board
82
consists of a first insulation layer or substrate
94
, a conductive ground layer
93
formed on the insulation layer
94
, and a second insulation layer
92
formed on the ground layer
93
. The feeder
89
a
is formed on the second insulation layer
92
and is connected to the chip
85
through a bump
91
.
The electromagnetically narrowed space
90
forms a waveguide. The waveguide has a cutoff frequency that is designed to be higher than a carrier frequency for microwave communication, to avoid the problem of cavity resonance and realize a compact module.
This module has the following problems:
(a) The housing
84
affects the antenna patterns
83
and
87
, and therefore, the antenna patterns
83
and
87
must sufficiently be separated from the housing
84
. This increases the size of the module and elongates the feeders
89
b
and
89
a
between the antenna patterns
83
and
87
and the chip
85
, to increase feeder losses.
(b) The lid
81
also affects the antenna patterns
83
and
87
. The lid
81
must be thick to provide a sufficient mechanical strength to protect the inside of the module. This, however, increases electromagnetic radiation losses.
In this way, the microwave T/R module of
FIGS. 2A and 2B
has the problem of large size to secure the performance of the antenna patterns and the problem of electromagnetic radiation losses and feeder losses.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a compact microwave T/R module.
Another object of the present invention is to provide a microwave T/R module capable of suppressing feeder losses and securing high-frequency performance.
Still another object of the present invention is to provide a microwave T/R module capable of suppressing electromagnetic radiation losses and securing the performance of antenna patterns.
Still another object of the present invention is to provide a microwave T/R module that is easy to process and secures high manufacturing yield.
In order to accomplish the objects, a first aspect of the present invention provides a microwave T/R module having at least a package, a receiver antenna pattern, and a transmitter antenna pattern. The package has at least a circuit board and a housing. The circuit board has a semiconductor chip mounted on the bottom surface thereof and serves as a lid to close the housing and contain the semiconductor chip in the housing. The receiver antenna pattern is formed on the top surface of the circuit board. The transmitter antenna pattern is formed on the top surface of the board at a different position from the receiver antenna pattern. When covered with the board, the housing defines an electromagnetically narrowed first space around the semiconductor chip. The first space serves as a waveguide whose cutoff frequency is higher than a carrier frequency for microwave communication. The receiver and transmitter antenna patterns are each electromagnetically connected to the semiconductor chip. More precisely, the antenna patterns and semiconductor chip are connected to each other through electromagnetic energy coupling of electromagnetic waves that pass through slots formed through a conductor layer having a shielding function. This electromagnetic connection or coupling must be discriminated from electrical connection made with flows of electric current. In this specification, the term “microwaves” covers a wide range of microwaves including millimeter waves. Microwave T/R modules of the present invention are applicable to microwaves of, preferably, 10 GHz or above, more preferably, 60 GHz or above. In this specification, the “board” or “circuit board” is a high-frequency circuit board having microstrip lines, etc., and being operable on microwaves of 10 GHz or above.
The microwave T/R module of the first aspect may have second and third spaces. The second space is formed just below the receiver antenna pattern and is so sized to produce a cavity resonance with respect to the carrier frequency for microwave communication. The third space is formed Just below the transmitter antenna pattern and is so sized to produce a cavity resonance with respect to the carrier frequency for microwave communication. The first, second, and third spaces form a single continuous space to simplify the structure of the module.
Consequently, the microwave T/R module of the first aspect is compact and capable of securing the performance of the antenna patterns.
A second aspect of the present invention provides a microwave T/R module having at least a package, a receiver antenna pattern, and a transmitter antenna pattern. The package has at least a housing for accommodating a semiconductor chip. The receiver antenna pattern is formed on the bottom surface of the housing. The transmitter antenna pattern is formed on the bottom surface of the housing at a different position from the receiver antenna pattern. The housing has an electromagnetically narrowed first space to surround the semiconductor chip. The first space serves as a waveguide whose cutoff frequency is higher than a carrier frequency for microwa
Iseki Yuji
Konno Mitsuo
Yamaguchi Keiichi
Bost Dwayne D.
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Redmon Joy
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