Oscillators – Solid state active element oscillator – Transistors
Reexamination Certificate
2001-10-09
2003-03-11
Mis, David C. (Department: 2817)
Oscillators
Solid state active element oscillator
Transistors
C331S096000, C331S1170FE, C331S1170FE, C331S1170FE, C331S175000, C331S17700V
Reexamination Certificate
active
06531928
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high-frequency module and more particularly to a high-frequency module such as a voltage-controlled oscillator including bare chip active elements or bare chip ICs including active elements mounted on a multilayer substrate.
2. Description of the Related Art
FIG. 4
is a schematic illustration showing the essential portion of a conventional voltage-controlled oscillator. The voltage-controlled oscillator
1
contains a multilayer substrate
2
. A bare chip IC
3
, a capacitor
4
, another electronic component
5
, and other elements, are mounted on the multilayer substrate
2
. A transistor in the oscillator stage defines an active element in the IC
3
. Moreover, a bare chip transistor itself in the oscillator stage may be mounted instead of the IC
3
. Furthermore, the voltage-controlled oscillator
1
is arranged such that an electrode pattern
6
is disposed on the multilayer substrate
2
and the electronic components mounted on the multilayer substrate
2
are connected.
The voltage-controlled oscillator
1
is constructed so as to have a circuit as shown in
FIG. 5
, for example. The voltage-controlled oscillator
1
contains a capacitor C
1
connected between the power-supply voltage Vc and the ground. Moreover, one end of a strip line SL
1
is connected to the power-supply voltage Vc, and the other end of the strip line SL
1
is connected to the cathode of a variable capacitance diode D
1
and one end of a capacitor C
2
. The anode of the variable capacitance diode D
1
is connected to the ground. Furthermore, the other end of the capacitor C
2
is connected to one end of each of a strip line SL
2
, a capacitor C
3
, and another capacitor C
4
. The other ends of the strip line SL
2
and the capacitor C
3
are connected to the ground. Furthermore, the capacitor C
4
is connected to a voltage divider circuit including resistors R
1
, R
2
, and R
3
.
This voltage divider circuit is connected between the power-supply voltage Vb and the ground. Moreover, the power-supply voltage Vb is connected to the collector of the npn transistor Tr
1
through a strip line SL
3
. The emitter of this transistor Tr
1
is connected to the collector of another npn transistor Tr
2
, and the emitter of the transistor Tr
2
is connected to one end of a resistor R
4
. The other end of the transistor R
4
is connected to the ground through a parallel circuit of a strip line SL
4
and a capacitor C
5
.
The connection point of the resistors R
1
and R
2
is connected to the base of the transistor Tr
1
. Furthermore, the connection point of the resistors R
2
and R
3
and the capacitor C
4
are connected to the base of the transistor Tr
2
. Moreover, one end of a capacitor C
6
is connected to the base of the transistor Tr
1
, and the other end of the capacitor C
6
and the base of the transistor Tr
2
are connected to the emitter of the transistor Tr
2
through a capacitor C
7
. Moreover, the emitter of the transistor Tr
2
is connected to the ground through a capacitor C
8
.
Furthermore, the connection point of the power-supply voltage Vb and the strip line SL
3
is grounded through a capacitor C
9
. Moreover, the connection point of the strip line SL
3
and the transistor Tr
1
is connected to an output terminal through a capacitor C
10
and simultaneously grounded through a capacitor C
11
. Furthermore, the connection point of the emitter of the transistor Tr
1
and the collector of the transistor Tr
2
is grounded through a capacitor C
12
.
In the voltage-controlled oscillator
1
shown in
FIG. 4
, the capacitor
4
that is disposed on the multilayer substrate
2
is the capacitor C
12
connected to the collector of the transistor Tr
2
in the oscillator stage, and one end of the capacitor
4
is connected to the collector of the transistor Tr
2
provided in the IC
3
and the other end is grounded. In this voltage-controlled oscillator
1
, the electronic components are, for example, flip-chip mounted, and the IC
3
is connected to an electrode pattern
6
through bumps
7
. As a matter of course, these electronic components may be connected to the electrode pattern
6
by wire bonding. Then, a sealing resin
8
is filled between the IC
3
and the multilayer substrate
2
to secure a sufficient mounting strength.
However, in such a voltage-controlled oscillator, when the sealing resin filled between the IC and the multilayer substrate is in contact with other electronic components, particularly a capacitor connected to the collector of a transistor in the oscillator stage, since the high-frequency impedance of the electronic component changes, fluctuations of the oscillator output level and the high-frequency level and deterioration of the C/N ratio, etc., are caused, and accordingly stable characteristics cannot be obtained. Furthermore, since thermal expansion coefficients of the sealing resin and the multilayer substrate are different, there is a problem in that the reliability in a thermal shock test and the reliability of the mounted electronic parts are degraded.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide a high-frequency module in which the influence of a sealing resin used to secure the mounting strength of active elements on a multilayer substrate is minimized and stable characteristics and a high reliability are achieved.
According to a preferred embodiment of the present invention, a high-frequency module includes a multilayer substrate, a bare-chip active element mounted on the multilayer substrate, a resin for sealing the active element on the multilayer substrate, and a grounding capacitance connected to the active element. In the high-frequency module, a strip line provided inside the multilayer substrate constitutes the grounding capacitance.
Furthermore, according to another preferred embodiment of the present invention, a high-frequency module includes a multilayer substrate, a bare-chip active element mounted on the multilayer substrate, a resin for sealing the active element on the multilayer substrate, and a grounding capacitance connected to the active element. In the high-frequency module, the grounding capacitance is preferably constructed by a strip line provided inside the multilayer substrate and a capacitor provided on the multilayer substrate.
Furthermore, according to another preferred embodiment of the present invention, a high-frequency module includes a multilayer substrate, a bare-chip active element mounted on the multilayer substrate, a resin for sealing the active element on the multilayer substrate, and a grounding capacitance connected to the active element. In the high-frequency module, the grounding capacitance is preferably constructed by a strip line provided inside the multilayer substrate and a microstrip line provided on the multilayer substrate.
In these high-frequency modules, the active element is preferably a transistor or an FET (field-effect transistor) in an oscillator stage and a voltage-controlled oscillator including the active element, and the collector of the transistor or the drain of the FET is connected to the grounding capacitance to construct the voltage-controlled oscillator.
When a grounding capacitance to be connected to an active element is constructed to include a strip line disposed in the multilayer substrate, the number of electronic components to be mounted on the multilayer substrate is significantly decreased and the possibility that the sealing resin for increasing the mounting strength of the active element may contact the other electronic components such as the grounding capacitance, or others, can be eliminated. Here, when the active element is connected to the other electronic components by an electrode disposed on the multilayer substrate, the influence of a stray capacitance generated between the active element and the electrode is increased by the sealing resin attached to the electrode for connection, but when the strip line is disposed
Sato Fumitoshi
Takai Kiyofumi
Keating & Bennett LLP
Mis David C.
Murata Manufacturing Co. Ltd.
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