Oscillators – Solid state active element oscillator – Transistors
Reexamination Certificate
2000-08-22
2002-03-19
Mis, David (Department: 2817)
Oscillators
Solid state active element oscillator
Transistors
C331S1170FE, C331S074000, C331S17700V, C331S185000
Reexamination Certificate
active
06359521
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oscillator with a buffer circuit, for use in a portable telephone or the like.
2. Description of the Related Art
FIG. 5
shows the construction of a conventional oscillator with a buffer circuit. An oscillation circuit
41
is of a common-collector connection type and comprises: an oscillation transistor
41
a
; a grounding capacitor
41
b
for connecting the collector of the oscillation transistor
41
a
to the ground so as to pass high frequencies; a feedback capacitor
41
c
connected between the base and the emitter of the oscillation transistor
41
a
; a feedback capacitor
41
d
connected between the emitter the oscillation transistor
41
a
and the ground; an inductance device
41
e
connected between the base of the oscillation transistor
41
a
and the ground; and a varactor diode
41
f
. The inductance device
41
e
takes the form of a strip line.
A buffer circuit
42
has an amplification transistor
42
a
and is an amplification circuit of a common-emitter connection type. The emitter of the amplification transistor
42
a
has a D.C. ground connection via an emitter bias resistor
42
b
and, further, connected to the ground via a bypass capacitor
42
c
so as to pass high frequencies.
The emitter of the oscillation transistor
41
a
and the collector of the amplification transistor
42
a
are connected via a choke inductor
43
. A common collector current is passed to the oscillation transistor
41
a
and the amplification transistor
42
a
by a power supply voltage Vb applied to the collector of the oscillation transistor
41
a.
A control voltage Vc is applied to the cathode of the varactor diode
41
f
via a choke inductor
44
, the oscillation circuit
41
oscillates at a frequency determined by the voltage value, and the oscillation signal is outputted from the emitter of the oscillation transistor
41
a
and is supplied to the base of the amplification transistor
42
a
via a coupling capacitor
45
. The amplified oscillation signal is outputted from the collector of the amplification transistor
42
a
to a load via a d.c. blocking capacitor
46
.
In the conventional oscillator with the buffer circuit, since the emitter of the oscillation transistor
41
a
and the collector of the amplification transistor
42
a
are connected to each other via the choke inductor
43
and the potential at the emitter and that at the collector are equal to each other. The power supply voltage Vb is therefore applied to the collector of the amplification transistor
42
a
with little attenuation of ripples of the power supply voltage Vb, and the ripple component is multiplexed on the oscillation signal amplified by the buffer circuit
42
. Consequently, the C/N ratio of the oscillation signal to be outputted deteriorates.
Since the phase of an amplified oscillation signal appearing at the collector of the amplification transistor
42
a
and that of an oscillation signal to be applied from the emitter of the oscillation transistor
41
a
to the collector of the amplification transistor
42
a
via the choke inductor
43
are opposite to each other, the level of the oscillation signal outputted from the collector of the amplification transistor
42
a
decreases.
Further, since the emitter of the oscillation transistor
41
a
is connected to the load via the choke inductor
43
and the d.c. blocking capacitor
46
, the load and the choke inductor
43
are arranged in series and interposed as an equivalent feedback capacitance between the emitter of the oscillation transistor
41
a
and the ground. The equivalent feedback capacitance changes according to the frequency characteristic of the reactance component of the load and a problem such that the oscillation frequency fluctuates occurs.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an oscillator with a buffer circuit in which deterioration in the C/N ratio due to ripples of the power supply voltage is lessened, fluctuations in the oscillation frequency caused by a change in the reactance of a load is suppressed and, further, an oscillation signal is sufficiently amplified by a buffer circuit.
In order to achieve the subject, according to the invention, there is provided an oscillator with a buffer circuit, comprising: an oscillation circuit having an oscillation transistor; and a buffer circuit which has an amplification transistor and amplifies an oscillation signal outputted from the oscillation circuit by the amplification transistor, wherein a power supply voltage is applied to the collector of either the oscillation transistor or the amplification transistor, the emitter of the other transistor has a D.C. ground connection, and the emitter of the transistor to which the power supply voltage is applied is connected to the collector of the other transistor via a resistor.
In the oscillator with a buffer circuit according to the invention, the power supply voltage is applied to the collector of the oscillation transistor, the oscillation circuit is of a common-collector connection type, the buffer circuit is an amplification circuit of a common-base connection type, and an oscillation signal is supplied from the emitter of the oscillation transistor to the emitter of the amplification transistor.
In the oscillator with a buffer circuit according to the invention, the power supply voltage is applied to the collector of the oscillation transistor, the oscillation circuit is an oscillation circuit of a common-base connection type, an amplification circuit of a common-emitter connection type is used as the buffer circuit, and an oscillation signal is supplied from the emitter of the oscillation transistor to the base of the amplification transistor.
In the oscillator with a buffer circuit according to the invention, the base of the oscillation transistor and the base of the amplification transistor are connected via a bias resistor, a base bias voltage is applied to the oscillation transistor, and the emitter of the amplification transistor has a D.C. ground connection.
In the oscillator with a buffer circuit according to the invention, the base of the oscillation transistor and the base of the amplification transistor are connected via a bias resistor, a base bias voltage is applied to the oscillation transistor, and the emitter of the amplification transistor is directly connected to the ground.
In the oscillator with a buffer circuit according to the invention, the power supply voltage is applied to the collector of the amplification transistor and an -amplifier of a common-emitter connection type is used as the buffer circuit.
In the oscillator with a buffer circuit according to the invention, the oscillation circuit is of a common-collector connection type and an oscillation signal is supplied from the emitter of the oscillation transistor to the base of the amplification transistor.
In the oscillator with a buffer circuit according to the invention, the base of the amplification transistor and the base of the oscillation transistor are connected via a bias resistor, a base bias voltage of the amplification transistor is applied, and the emitter of the oscillation transistor has a D.C. ground connection.
In the oscillator with a buffer circuit according to the invention, the base of the amplification transistor and the base of the oscillation transistor are connected via a bias resistor, a base bias voltage of the amplification transistor is applied, and the emitter of the oscillation transistor is directly connected to the ground.
REFERENCES:
patent: 4797638 (1989-01-01), Usui et al.
patent: 11-312924 (1999-11-01), None
Ishigaki Isao
Nakano Kazuhiro
Alps Electric Co. ,Ltd.
Beyer Weaver & Thomas LLP
Mis David
LandOfFree
Oscillator with buffer circuit in which deterioration in C/N... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Oscillator with buffer circuit in which deterioration in C/N..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oscillator with buffer circuit in which deterioration in C/N... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2822958