Oscillators – Plural oscillators – Adjustable frequency
Reexamination Certificate
2001-05-31
2002-12-31
Mis, David C. (Department: 2817)
Oscillators
Plural oscillators
Adjustable frequency
C331S096000, C331S1170FE, C331S1170FE, C331S17700V, C331S179000
Reexamination Certificate
active
06501338
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a three-band switching oscillator for use in portable telephones or the like, which is designed to output an oscillation signal in any one of three frequency bands.
2. Description of the Related Art
The recent oscillators have been designed to make oscillation in a plurality of frequency bands.
FIG. 5
is an illustration of an arrangement of a conventional three-band switching oscillator handling three systems, for example, DCS (cellular telephone using 1800 MHz band), PCS (cellular telephone using 1900 MHz band) and GSM (cellular telephone using 900 MHz band). In addition, this takes four modes: output of an oscillation signal in any one of frequency bands and non-output of an oscillation signal in these frequency bands.
In
FIG. 5
, a first voltage-controlled oscillator
31
is composed of a first oscillation transistor
32
and a first resonance circuit
33
connected to the base thereof, and serves as a common collector type oscillator. The first resonance circuit
33
includes a first varactor diode
33
a
and resonant lines
33
b
and
33
c
connected in series to each other, while a switching diode
33
d
is connected in parallel with one resonant line
33
c
. The anode of the first varactor diode
33
a
is grounded while the cathode thereof is connected to a control terminal
34
. Moreover, the cathode of the switching diode
33
d
is in a grounded condition.
An oscillation signal is outputted from the emitter of the first oscillation transistor
32
and is inputted to the base of a first amplification transistor
35
a
constituting a first amplifier
35
. In addition, the oscillation signal amplified is outputted from the collector of the first amplification transistor
35
a.
The first amplification transistor
35
a
and the first oscillation transistor
32
are connected in series with respect to a power supply, and a power supply voltage Vb is applied to the collector of the first amplification transistor
35
a
, while a voltage is applied through the emitter thereof to the collector of the first oscillation transistor
32
. In addition, resistors
36
,
37
and
38
for setting a bias voltage are connected to the base of the first amplification transistor
35
a
and the base of the first oscillation transistor
32
, and the resistor
36
is connected to the emitter of the first switching transistor
39
. The power supply voltage Vb is given to the collector of the first switching transistor
39
, while the base thereof is connected to as first switching terminal
40
. The anode of the switching diode
33
d
is connected to a second switching terminal
41
.
Meanwhile, a second voltage-controlled oscillator
51
is composed of a second oscillation transistor
52
and a second resonance circuit
53
connected to the base thereof, and acts as a common collector type oscillator. The second resonance circuit
53
includes a second varactor diode
53
a
, a resonant line
53
b
, and other elements. The anode of the second varactor diode
53
a
is grounded, while the cathode thereof is connected to the control terminal
34
.
An oscillation signal is outputted from the second oscillation transistor
52
and is inputted to the base of a second amplification transistor
54
a
constituting a second amplifier
54
. In addition, the oscillation signal amplified is outputted from the collector of the second amplification transistor
54
a.
The second amplification transistor
54
a
and the second oscillation transistor
52
are connected in series with respect to the power supply, and the power supply voltage Vb is applied to the collector of the second amplification transistor
54
a
, while a voltage is supplied through the emitter thereof to the collector of the second oscillation transistor
52
. In addition, resistors
55
,
56
and
57
for setting a bias voltage are connected to the base of the second amplification transistor
54
a
and the base of the second oscillation transistor
52
, and the resistor
55
is connected to the emitter of a second switching transistor
58
. The power supply voltage Vb is given to the collector of the second switching transistor
58
, and the base thereof is connected to a third switching terminal
59
.
In the above-mentioned arrangement, a high-level or low-level switching voltage coming from the body side of the portable telephone is applied to the first switching terminal
40
, the second switching terminal
41
and the third switching terminal
59
. Referring to
FIG. 6
, a description will be given of an operation of each of the voltage-controlled oscillators
31
and
51
based on;this switching voltage. In the description which will be given with reference to
FIG. 6
, the first to third switching terminals
40
,
41
and
59
are taken as SW
1
, SW
2
and SW
3
, respectively, while the high-level and low-level switching voltages are taken as (H) and (L), respectively. In addition, the first voltage-controlled oscillator
31
is taken as VCO
1
and the second voltage-controlled oscillator
51
is taken as VCO
2
.
First, when the SW
1
is at (L), the first switching transistor
39
turns off to stop the bias voltage supply to the base of the first oscillation transistor
32
, thereby making the first voltage-controlled oscillator
31
inoperative. Contrary to this, when the SW
1
is at (H), it becomes operative. In addition, when the SW
2
is at (L) in the operative condition, the switching diode
33
d
turns off, and the VCO
1
oscillates in a first frequency band which is low in frequency. This frequency band is for use in the DCS system. On the other hand, when the SW
2
is at (H), the switching diode
33
d
turns on, so the VCO
1
oscillates in a second frequency band which is high in frequency. This frequency band is for use in the PCS system.
In like manner, when the SW
3
is at (L), the second switching transistor
58
turns off to stop the bias voltage supply to the base of the second oscillation transistor
52
, so the second voltage-controlled oscillator
51
becomes inoperative. Contrary to this, when the SW
2
is at (H), it becomes in an actuated condition, and the oscillation takes place in a third frequency band. This frequency band is available for the GSM system.
That is, in the above-described operation, a high-level or low-level switching voltage is inputted to the first to third switching terminals
40
,
41
and
59
, and eight switching modes are attainable according to combinations thereof.
FIG. 6
shows these switching modes, and of these, the modes No.
1
and No.
2
are the same operational contents and the modes No.
3
and No.
4
are the same operational contents, so only one modes are put to use. In addition, since the first voltage-controlled oscillator
31
and the second voltage-controlled oscillator
51
are not put to use at the same time, the modes No.
7
and No.
8
are not employable.
In the above-described conventional three-band switching oscillator, the three switching terminals (
40
,
41
,
59
) are used in order to obtain four necessary switching modes. The most important point to an oscillator for use in a portable telephone is size reduction, and hence, various improvements have been made in order to realize the size reduction. An decrease in number of terminals contributes greatly to the size reduction; however, an approach to decrease the number of terminals has not been made until now.
Furthermore, in the conventional three-band switching oscillator, since the binary switching voltages are applied to the three switching terminals, unnecessary switching modes come about. This complicates the circuit on the body side of a portable telephone which generates the switching voltages.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a three-band switching oscillator capable of decreasing the number of switching terminals for achieving the size reduction and of simplifying the arrangement of the body side of a portable telephone which generates switching voltages.
Hasegawa Isao
Nakano Kazuhiro
Noumi Hiroki
Alps Electric Co. ,Ltd.
Mis David C.
LandOfFree
Three-band switching oscillator suitable for size reduction does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Three-band switching oscillator suitable for size reduction, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Three-band switching oscillator suitable for size reduction will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2978113