JPS6327883B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a feedback type oscillation device suitable for integration into an integrated circuit.

FIG. 1 and FIG. 2 show the basic circuit of a conventionally used feedback type oscillator. Note that the DC bias circuit for the base electrode and collector electrode of the transistor 1 is omitted because it is not particularly required in the description of the present invention. In Figures 1 and 2, 3 is an emitter resistor, 4 is a grounding capacitor with an emitter electrode, transistor 1 is used with its emitter grounded, and a feedback circuit 2 is connected between the base electrode and collector electrode of transistor 1. The oscillation output is taken out from a terminal 5, which is a part of the feedback circuit, through a coupling capacitor 7 or a transformer 8, and is supplied to a load circuit 6.

The oscillation device having the above circuit configuration has excellent features such as requiring a minimum of one transistor and being able to realize a simple output extraction configuration.

However, when the above-mentioned oscillation device is made into a monolithic integrated circuit, variations in the electrical characteristics of the transistors and variations in the absolute value of the bias resistance are unavoidable, which causes the DC operating point of the transistor to vary and the characteristics of the oscillator to vary. Therefore, it has been difficult to integrate an oscillation device with a conventional circuit configuration.

Further, the configuration in which the oscillation output is taken out from a part of the feedback circuit has the problem that when the conditions of the output load circuit change, the feedback characteristics of the feedback circuit change, and the oscillation frequency and oscillation output level fluctuate.

On the other hand, as electronic circuits are becoming more integrated today and their applicable frequencies are moving toward higher frequencies, there is a long-awaited realization of an oscillation device that can operate stably in the VHF band and is suitable for integrated circuits. .

The present invention has been made based on the above points,
It is an object of the present invention to solve the problems in the conventional oscillation device described above and to provide an oscillation device suitable for integration into an integrated circuit.

FIG. 3 shows the basic circuit configuration of an embodiment of the present invention. To explain this, a feedback circuit 2 is connected between the base electrode and the collector electrode of the first transistor 1.
By connecting, a feedback type oscillation circuit is realized, and by connecting the emitter electrode of the second transistor 9 to the emitter electrode of the transistor 1,
The transistor 9 and the transistor 1 constitute a differential amplifier circuit, and the oscillation output of the oscillator is taken out from the collector electrode of the second transistor 9 and supplied to the load circuit 6.

When the oscillation device is configured as shown in Fig. 3, the problem that the DC bias point of transistor 1 fluctuates due to variations in the electrical characteristics of the transistors and variations in the absolute value of the bias resistance that occur when the transistors are manufactured can be solved by the second transistor. It is stabilized by configuring a differential amplifier circuit together with 9.

In addition, by taking out the oscillation output from the collector electrode of the transistor 9 which is emitter-coupled with the transistor 1, the transistor 9 acts as a buffer between the transistor 1, the oscillation circuit section, and the output load circuit 6, and the load condition of the output load circuit 6 is adjusted. This has the effect of stably operating the oscillation circuit against changes.

FIG. 4 is a circuit diagram of a specific embodiment of the present invention. Components having the same functions as those in FIG. 3 are given the same reference numerals. In the figure, 14 and 15 are collector load resistances of transistor 1 and transistor 9, respectively, and are load resistance 1
4 is fed back to the base electrode of the first transistor 1 through the feedback circuit 2a from the emitter electrode of the third transistor 12 used as a common collector. At the same time, the output taken out to the load resistor 15 is transferred to the fourth transistor 1 whose collector is shared in common with the third transistor 12.
The signal is supplied from the emitter electrode of No. 6 to the load circuit 6 through the coupling capacitor 22.

As described above, one transistor constituting the differential amplifier circuit is used as an active element of the oscillation circuit,
When the other transistor is configured to take out its oscillation output, collector currents with a phase relationship of 180° flow to the collector terminals of transistors 1 and 9, and the sum of the currents flowing to load resistors 14 and 15 is Furthermore, due to the collector current described above, collector voltages having the same 180° phase relationship are obtained from the load resistors 14 and 15, and the collector currents of the transistors 12 and 16 driven by this collector voltage are also 180° from each other. There is a phase relationship of .degree., and the sum of the collector currents of transistors 12 and 16 is also constant. As a result, no oscillating current accompanying the oscillation operation of the oscillation circuit appears at the power supply terminal 18, which has the effect of preventing a portion of the oscillation output from leaking to the outside through the power supply terminal.

Further, the transistor 12 constitutes the feedback circuit 2a and the feedback circuit 2 of the oscillation circuit, and also converts the impedance of the collector electrode of the amplifying transistor 1 of the oscillation circuit to match the impedance of the base electrode of the transistor 1, and oscillates. This has the effect of ensuring that the signal is returned efficiently. Further, the transistor 16 performs an impedance conversion function similarly to the transistor 12, and the output terminal 1
This has the effect of lowering the impedance at 0 and facilitating high frequency handling.

In addition, the load resistors 14 and 15 are connected to the transistor 1
By changing the resistance value of the load resistor, the output impedance at terminals 19 and 10 can be arbitrarily selected within a range that allows the DC bias conditions of transistor 9.

Further, by configuring the circuit symmetrically as described above, it is possible to stabilize the operation of the DC circuit, and therefore it is suitable for integrating the present oscillation device.

Next, the fifth transistor 13 and the sixth transistor 17 have a current sinking function that determines the emitter current of the transistors 12 and 16, respectively, and the voltage supplied to the base electrode of the transistor 17 is externally controlled by the variable resistor 23. By changing the voltage, the gain of the transistor 16 can be controlled in a DC manner, and the oscillation output at the output terminal 10 can be easily controlled (see FIG. 5).

The capacitor 11 connects the base electrode of the second transistor 9 to AC ground, and has the effect of increasing the efficiency of extracting the oscillation output. The coupling capacitor 22 can be used with a value that has a sufficiently low reactance resistance at a desired oscillation frequency, and is used for direct current blocking.

In transistors 1 and 12 that constitute a feedback oscillation circuit, the signal phase at the emitter electrode of transistor 12 is delayed at the desired oscillation frequency within a range of 270° and 360° with respect to the signal phase at the base electrode of transistor 1. By setting the transistors 1 and 12 and the load resistor 14, the piezoelectric vibrator 21 having resonance characteristics at the oscillation frequency is connected to the terminal 20 to which the base electrode of the transistor 1 is connected and the emitter electrode of the transistor 12. With a simple configuration of the feedback circuit 2a connected in series between the terminals 19, a feedback type oscillation device can be realized.

In addition, if the above phase relationship cannot be obtained at the desired oscillation frequency,
As shown in FIG. 2, an oscillation device can be realized by correcting the phase lead and delay by using the inductance element 24 and the capacitor 25 as shown. Note that this feedback circuit 2a does not necessarily need to use a piezoelectric vibrator, and the desired oscillation device can be realized by connecting a resonant circuit consisting of an inductance element 26 and capacitors 27 and 28 as shown in FIG. 6c. can.

As is clear from the above description, the present invention uses a second transistor in addition to the first transistor used as an amplification element of an oscillation device, and configures a differential amplifier circuit with the first and second transistors. Therefore, the oscillation device can be integrated into an integrated circuit, and the second transistor does not have a buffering effect between the oscillation device and the output load circuit, and the excellent effect of stabilizing the operation of the oscillation device can be obtained.

Furthermore, in the present invention, by configuring the feedback circuit and the output circuit using the third and fourth transistors that share the collector, the feedback efficiency in the feedback circuit is improved and the oscillation circuit is stabilized. ,
The output circuit can be designed to have a low output impedance, which has the effect of facilitating high frequency handling.

Furthermore, the fifth and sixth transistors are configured as a current sink circuit for the third and fourth transistors, and the DC voltage applied to the base electrode of the sixth transistor can be changed, thereby forming a feedback type oscillator. Another effect is that the level of the oscillation output supplied to the output load circuit can be controlled in a direct current manner without affecting the first and third transistors.

Furthermore, by configuring the phase relationship between the base electrode of the first transistor and the emitter electrode of the third transistor as described above, it is possible to realize an oscillation device by simply using a piezoelectric vibrator in the feedback circuit. There is an effect that it can be done.

Note that the above-described embodiment of the present invention uses a bipolar transistor as an active element, but the same operation and effect can be achieved even if a junction field effect transistor or a MOS field effect transistor is used instead. It goes without saying that these are obtained and included in the present invention.

[Brief explanation of the drawing]

1 and 2 are basic circuit configuration diagrams of a conventional oscillation device, FIG. 3 is a basic circuit configuration diagram of an embodiment of the present invention, and FIG. 4 is a circuit diagram of a specific embodiment of the present invention. , FIG. 5 is a diagram showing an example of oscillation output level control characteristics, and FIGS. 6a, b, and c are diagrams showing an example of the configuration of a feedback circuit that can be used in the present invention. 1, 9, 12, 13, 16, 17...transistor, 2, 2a...feedback circuit, 18...power terminal, 21...piezoelectric vibrator, 23...variable resistor.

Claims (1)

[Claims] 1. A differential amplifier circuit is configured including a first and a second transistor, and the same circuit is subsequently connected to each collector circuit of the first and second transistors, so that a current complementary type symmetric A feedback circuit having a positive feedback characteristic at a desired oscillation frequency is provided between the base electrode and the collector electrode of the first transistor and a subsequent circuit end to constitute a feedback type oscillation circuit, and the first An oscillation device characterized in that the oscillation output of the oscillation circuit is taken out from the collector terminal of the second transistor and the subsequent circuit end through emitter coupling of the second transistor and the second transistor. 2. In the description of claim 1, a load resistor is connected between the collector electrodes of the first and second transistors and a power supply terminal commonly used for the first and second transistors. In addition, the collector electrode of the first transistor is connected to the base electrode of the third transistor, the collector electrode of the second transistor is connected to the base electrode of the fourth transistor, and the collector electrode of the third transistor is connected to the base electrode of the third transistor. The feedback circuit is provided between the emitter electrode and the base electrode of the first transistor to constitute a feedback type oscillation circuit, and the oscillation output is extracted from the emitter electrode of the fourth transistor. oscillation device. 3. In the description of claim 2, the emitter electrode of the third transistor is connected to the collector electrode of the fifth transistor, the fifth transistor is used as a constant current source for the third transistor, and the fifth transistor is connected to the collector electrode of the fifth transistor. The collector electrode of a sixth transistor is connected to the emitter electrode of the fourth transistor, and the sixth transistor is used as a constant current source for the fourth transistor, and the DC voltage applied to the base electrode of the sixth transistor is changed. By this,
An oscillation device characterized in that the gain of the fourth transistor is controlled to control the level of the oscillation output. 4. In the statement of claim 1, 2, or 3, a piezoelectric vibrator is used in the feedback circuit, one of two terminals of the piezoelectric vibrator is used as an input terminal of the feedback circuit, and the other An oscillation device characterized in that a terminal of the oscillator is connected to an output terminal.