Oscillators – Plural oscillators – Selectively connected to common output or oscillator...
Reexamination Certificate
2000-08-08
2001-09-18
Mis, David (Department: 2817)
Oscillators
Plural oscillators
Selectively connected to common output or oscillator...
C331S048000, C331S077000, C331S1170FE, C331S175000, C331S17700V
Reexamination Certificate
active
06292063
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a two-band oscillation apparatus to be used in a hand-held telephone set used in common for different two systems.
2. Description of the Related Art
FIG. 3
illustrates a structure of a two-band oscillation apparatus of the related art consisting of a first oscillator
21
, a second oscillator
22
and an amplifier
23
. The first oscillator
21
is structured to oscillate at a low frequency band (Lf) of about 880 MHz to 940 MHz. The second oscillator
22
is structured to oscillate at a high frequency band (Hf) of about 1805 MHz to 1920 MHz which is higher than the oscillation frequency of the first oscillator
21
.
The power source voltage (Vb) is applied to the first oscillator
21
or second oscillator
22
through a first change-over switch
24
. The oscillator to which the power source voltage is applied operates to output an oscillation signal. An amplifier
23
amplifies such oscillation signal.
The amplifier
23
is formed as an emitter-grounded tuning amplifier. The power source voltage is impressed to the collector of the amplifying transistor
23
a
via a choke inductor
23
b.
The emitter of amplifying transistor is grounded through a bias resistor
23
c
and a bypass capacitor
23
d.
Moreover, a series circuit of a tuning capacitor
23
e
and a switching diode
23
f
is connected between the collector and ground. The cathode of switching diode
23
f
is grounded and a switching voltage (Vs) is impressed to the anode thereof via a second change-over switch
25
. The second change-over switch
25
is changed over in conjunction with the first change-over switch
24
.
When the power source voltage is impressed to the first oscillator
21
with the first change-over switch
24
, a switching voltage is impressed to the anode of the switching diode
23
f
of the amplifier
23
via the second change-over switch
25
to turn ON the switching diode
23
f.
An oscillation signal of the low frequency band output from the first oscillator
21
is input to the amplifier
23
. In the amplifier
23
, a parallel tuning circuit is formed of a choke inductor
23
b
and a tuning capacitor
23
e
when the switching diode
23
f
turns ON. The tuning frequency is set almost to be matched with the low frequency band. Therefore, the amplifying characteristic of the amplifier
23
shows the peak amplification degree in the low frequency band as illustrated in A of FIG.
4
. The oscillation signal of the low frequency band input to the amplifier
23
is amplified to a large extent. The amplified oscillation signal is output from the collector of amplifying transistor
23
a
via a DC-cut capacitor
23
h.
Conversely, when the power source voltage is impressed to the second oscillator
22
with the first change-over switch
24
, a change-over voltage is no longer impressed to the anode of the switching diode
23
f
of amplifier
23
with the second change-over switch
25
to turn OFF the switching diode
23
f.
An oscillation signal of the high frequency band output from the second oscillator
22
is then input to the amplifier
23
. In the amplifier
23
, when the switching diode
23
f
turns OFF, its terminal capacitance is connected in series to the tuning capacitor
23
e.
The combining capacitance of these elements is connected in parallel to the choke inductor
23
b
to form a parallel tuning circuit. The tuning frequency is set almost to be matched with the high frequency band. Therefore, the amplifying characteristic of the amplifier
23
has the peak amplification degree in the high frequency band as illustrated in B of FIG.
4
. The oscillation signal of high frequency band input to the amplifier
23
is amplified to a large extent. The amplified oscillation signal is output from the collector of amplifying transistor
23
a
via the DC-cut capacitor
23
h.
As explained above, the two-band oscillating apparatus of the related art forms an amplifier to amplify the oscillating signal of two frequency bands with a tuning amplifier. Moreover the tuning frequency of the tuning circuit of the tuning amplifier is changed over. Therefore, a large number of parts are required to impede reduction in size of the circuit.
SUMMARY OF THE INVENTION
Therefore, it is an object of the invention to provide a two-band oscillator which reduces the number of parts by simplifying the structure of amplifier and assures the higher amplification degree in two oscillation frequencies without changing-over of the amplifying characteristic.
As a means for overcoming the problems explained above, the two-band oscillation apparatus of the present invention comprises a first oscillator for outputting the oscillation signal of the first frequency band, a second oscillator for outputting the oscillation signal of the second frequency band higher than the first frequency band, and an emitter-grounded amplifier including an amplifying transistor to amplify the oscillation signal of the first frequency band or the oscillation signal of the second frequency band with the amplifying transistor. A bias resistor is connected between the emitter of the amplifying transistor and the ground. Moreover a first series resonance means having the series resonance frequency in the first frequency band and a second series resonance means having the series resonance frequency in the second frequency band are connected between the emitter and the ground.
Moreover, the two-band oscillating apparatus of the present invention uses a first capacitance element having the self series resonance frequency in the first frequency band as the first series resonance means and a second capacitance element having the self series resonance frequency in the second frequency band as the second series resonance means.
Moreover, the two-band oscillating apparatus of the present invention uses a first chip capacitor as the first capacitance element, while a second chip capacitor as the second capacitance element.
Moreover, the two-band oscillating apparatus of the present invention structures the first series resonance means with a first capacitance means and a first inductance means, and the second series resonance means with a second capacitance means and a second inductance means.
In addition, the two-band oscillating apparatus of the present invention also comprises a first conductor to connect the first capacitance means between the emitter and the ground and a second conductor to connect the second capacitance means between the emitter and the ground and defines the first conductor as the first inductance means and the second conductor as the second inductance means.
REFERENCES:
patent: 5852384 (1998-12-01), Sakakura et al.
patent: 0 886 384 A (1998-12-01), None
patent: 1002941 (1965-09-01), None
patent: 9-294018 (1997-09-01), None
patent: 11-298242 (1999-11-01), None
Ikarashi Yasuhiro
Tanemura Takeshi
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Mis David
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