Amplifiers – With semiconductor amplifying device – Including field effect transistor
Reexamination Certificate
1999-11-23
2001-10-30
Pascal, Robert (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including field effect transistor
C330S283000, C330S302000
Reexamination Certificate
active
06310517
ABSTRACT:
TECHNICAL FIELD
The present invention is related to a microwave amplifier arranged by employing a field-effect transistor.
BACKGROUND OF THE INVENTION
In general, a conventional microwave amplifier is known from, for example, Japanese Patent Laid-open No. 285811/1986. This first prior art will how be explained with reference to FIG.
21
.
In this drawing, reference numeral
110
shows a microwave amplifier; reference numeral
111
indicates a field-effect transistor (will be referred to as an “FET”); reference numeral
112
represents a resistor; and reference numeral
113
shows a connection conductor for connecting the FET
111
to the ground plane. This connection conductor
113
functions as a tip shortcircuit stub which contains an inductance component in a high frequency field. Also, reference numeral
114
represents a tip open stub, the length of which is equal to a ¼ wavelength at an operating frequency of the circuit. Specifically, the ¼ wavelenghth means a ¼ of a wavelength. The wavelength corresponds to the operating frequency of the circuit.
As indicated in
FIG. 22
, since the connection conductor
113
owns the inductance component “A”, the FET
111
can be grounded by employing only the connection conductor
113
at a low frequency under which the inductance component “A” is negligible. However, the inductance component “A” is not negligible in a high frequency, and thus, a gain of the FET
111
is deteriorated. As a consequence, it is possible to avoid such a gain deterioration of the FET
111
by employing the tip open stub
114
so as to ground the FET
111
in the high frequency sense. Also, at this stage, in order to suppress unwanted oscillation of the FET
111
, the resistor
112
is connected.
Next, a description will now be made of a second prior art with reference to FIG.
23
.
FIG. 23
is the diagram for representing the low noise amplifier described in “HEMT DIRECT COOLING TYPE LOW NOISE AMPLIFIER”, SHINGAKU GIHO MW 92-149,
Japanese Electronic Information Communication Institute. In this drawing, reference numeral
120
indicates a low noise amplifier; reference numeral
121
represents an FET; and reference numeral
122
shows an inductor. A source electrode of the FET
121
is grounded via the inductor
122
. As a result, the input impedance for minimizing noise of the FET
121
can be located in the vicinity of the impedance for minimizing the reflection, and also both the noise figure and the reflection coefficient on the input side can be improved at the same time.
On the other hand, any of the above-described prior art owns the below-mentioned problems. First, the microwave amplifier
110
corresponding to the first prior art owns such a problem that unnecessary electric power is consumed by the resistor
112
connected to the source electrode of the FET
111
, and thus, the output power characteristic would be deteriorated. Also, as shown in
FIG. 24
, the low noise amplifier
120
corresponding to the second prior art owns such a problem that since the inductor
122
connected to the source electrode of the FET
121
owns the stray capacitance “B”, this inductor is resonated at a predetermined frequency, and thus, operation would become unstable.
The present invention has an object to solve these problems.
DISCLOSURE OF THE INVENTION
A microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, wherein: both an inductor and a resistor are loaded in a parallel manner between a source electrode of the field-effect transistor and the ground.
Also, a microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, wherein: a first inductor and a stabilizing circuit are loaded in a parallel manner between a source electrode of said field-effect transistor and the ground; and the stabilizing circuit is equipped with a second inductor and a resistor series-connected to the second inductor, the second inductor is resonated at a frequency different from another frequency at which the first inductor is resonated by a stray capacitance component.
Further, a microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, wherein: a first inductor and a stabilizing circuit are loaded in a parallel manner between a source electrode of the field-effect transistor and the ground; the stabilizing circuit is equipped with a resonant unit in which a second inductor is parallel-connected to a capacitor, and a resistor series-connected to the resonant unit; and the resonant unit is resonated at a frequency different from another frequency at which the first inductor is resonated by a stray capacitance component.
Also, a microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, wherein: a first inductor and a stabilizing circuit are loaded in a parallel manner between a source electrode of the field-effect transistor and the ground; the stabilizing circuit is equipped with a resonant unit in which a second inductor is series-connected to a capacitor, and a resistor series-connected to the resonant unit; and the resonant unit is resonated at a frequency different from another frequency at which the first inductor is resonated by a stray capacitance component.
Further, a microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, wherein: an inductor and a stabilizing circuit are loaded in a parallel manner between a source electrode of the field-effect transistor and the ground; the stabilizing circuit is equipped with a short stub and a resistor series-connected to the short stub; and a length of the short stub is equal to a ½ wavelength at a frequency where the inductor is resonated by a stray capacitance component.
Further, a microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, wherein: an inductor and a stabilizing circuit are loaded in a parallel manner between a source electrode of the field-effect transistor and the ground; and the stabilizing circuit is equipped with a short stub and a resistor series-connected to the short stub; and a length of the short stub is equal to a ¼ wavelength at a frequency different from such a frequency that the inductor is resonated by a stray capacitance component.
Also, a microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, comprising: an inductor loaded between a source electrode of the field-effect transistor and the ground; a resistor, one end of which is connected to the electrode; and an open stub connected to the Other end of the resistor, the length of which is equal to a ½ wavelength at a frequency where the inductor is resonated by a stray capacitance component.
Further, a microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, comprising: an inductor loaded between a source electrode of the field-effect transistor and the ground; a resistor, one end of which is connected to the electrode; and an open stub connected to the other end of the resistor, the length of which is equal to a ¼ wavelength at a frequency different from such a frequency that the inductor is resonated by a stray capacitance component.
Also, a microwave amplifier, according to the present invention, is featured by such a microwave amplifier arranged by employing a field-effect transistor, comprising: an inductor loaded between a source electrode of the field-effect transistor and the ground; a resistor connected between a drain electrode of the field-effect transistor and an output terminal; an
Itoh Yasushi
Nakahara Kazuhiko
Choe Henry
Mitsubishi Denki & Kabushiki Kaisha
Pascal Robert
Rothwell Figg Ernst & Manbeck
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