SU1538214A1 - Self-excited oscillator - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to increase the level and stability of the output power when changing parameters of an external load. The oscillator contains transistors 1 and 2, capacitors 3-7, inductors 8-10 and power supply 11. The increase in output power is achieved by matching the input circuit of the active device with the source of the excitation signal in the autogenerator. In this case, conditions are created for efficiently driving a composite transistor consisting of transistor 1 and input transistor 2. This provides oscillation generation conditions with a high output power level when transistors 1 and 2 develop their full nominal powers and deliver them to an oscillating system. Because The autogenerator is an adaptive device with respect to the change in the reactive component of the external load; it has a lower sensitivity of the output power level to such changes. 1 sludge.

Description

The invention relates to radio engineering and can be used as a powerful source of electrical oscillations.

The purpose of the invention is to increase the level and stability of the output power when changing the parameters of the external load.

The drawing shows a structural electrical circuit of the oscillator.

The oscillator contains the first 1 and second 2 transistors, the first 3, second 4, third 5, fourth 6 and fifth 7 capacitors, the first 8, second 9 and third 10 inductors: and a power source 11.

The oscillator operates as follows.

When you turn on the power supply 1 1 on the electrodes of the composite transistor formed by the connection of the first 1 and second 2 transistors, the supply voltage and the bias voltage appear. The bias voltage is selected 25 as a trigger, due to which there is a soft self-excitation of the oscillator. The composite transistor begins to amplify the fluctuation oscillations present on the base of the first transistor 2, after which the amplified oscillations through the positive feedback circuit formed by the second inductor 9, third 5, fourth 6 and fifth 7 capacitors, and filtering these oscillations, come back into the base circuit of the second transistor 2. The amplitude of the oscillations in the oscillator begins to increase. The process of increasing the amplitude ends with the establishment of a stationary mode with a constant steady-state oscillation amplitude.

An increase in the locking bias at the second output of the power source 1 ', caused by the increase in the constant component of the base current of the second transistor 2, gradually transfers the second transistor 2 into the most favorable mode of operation with current cutoff with an increase in the amplitude of oscillations. The first transistor 1 operates in a continuous current cutoff mode, which is ensured by the inclusion of a third inductor 10 (this is a blocking choke) between its base and the emitter, which creates a mode of operation of the first transistor with zero bias.

Only a small fraction of P _n of the total power P, and generated by the composite transistor, necessary for its excitation, branches into the positive feedback circuit (POS). The main and largest share of P _{Bb (X} from the power of P _k passes through the output matching circuit formed by the first 3 and second 4 capacitors and the first inductor 8 and also performs the function of an output filter to the output of the oscillator, and then to the external load.

The indicated distribution of powers P _B and P _{B ) X is} provided by a certain choice of the input resistance of the PIC circuit R _noc and the input resistance Re _{U of the} output matching circuit (the PIC transforms Z _{V) (} in R _nocs and the output matching circuit transforms the load resistance of the oscillator into resistance R _CU J.

Rrroc = 472P ₅ ;

^R cc = U ^ / 2P _6blx , (1) where U ² _K1 is the amplitude of the first harmonic of the voltage at the output electrode of the composite transistor, i.e. at the junction point of the collectors of the first 1 and second 2 transistors.

The PIC circuit and the input matching circuit are connected in parallel with their input terminals to the output electrode of the composite transistor, so the parallel connection of their input resistances R _Los gives the total resistance R _XiX p equal to the critical resistance (which is necessary for the composite transistor to operate in the optimal critical mode), which is loaded by a composite transistor at its output electrode.

The circuit of the PIC is composed as follows.

The first G-link, counting from the base of the second transistor 2, is switched on. The circuit is a circuit with a negative phase shift. The B-circuit is a low-pass filter, therefore, to give the PIC circuit pronounced selective properties (as a frequency-charging circuit), an A-circuit, a high-pass filter, is connected to the B-circuit. However, the Λ-chain creates a phase shift of the positive sign ⁵ 15381 ka, and therefore, compensates for the necessary negative phase shift introduced by the B-chain. Therefore, another negative phase shift circuit is added to the A chain, i.e. 5 more one B-chain. Such a POS circuit structure is capable of providing complete phasing of the oscillator and no additional connection of G-links is required.

A positive effect in the oscillator in the form of an increase in the output power is achieved due to the fact that it ensures the matching of the input circuit of the active device with the source of the exciting signal. In this case, the conditions for the most efficient excitation of the composite transistor are created, and therefore the conditions for generating oscillations with a large level of 20 output power, when the first 1 and second 2 transistors develop their full rated powers and transfer them to the oscillating system. The PIC circuit loaded on Ζ _βΧ creates in the circuit 25 of the oscillator a phase shift Cp _pos , at which complete phasing is achieved. The composite transistor turns out to be loaded with purely active resistance 3 in its output electrode (that is, the oscillatory system consisting of a POS circuit and an output matching circuit turns out to be tuned to resonance), which means that the maximum power output to the load.

The weakening of the effect on the output power level of changes in the reactive component of the external load resistance is due to the following factors. 4

When the reactive component of the load resistance changes, a certain reactivity is introduced through the output matching circuit, which causes a violation of the phase relations q in its circuit (complete phasing is violated) and helps to reduce the output power. However, introducing a certain reactivity into the oscillator leads to a change in the frequency of 5 generated oscillations, as a result of which the active R _BX and reactive X _6x components of the input resistance of the composite transistor change (the composite transistor has a sharper $ frequency dependence of R _{& x} h Χ _0χ than that of a single transistor) . When changing r and X _Bx varies and the phase shift circuit PIC cf. _{ps> s,} and were

6 is the input resistance of the PIC circuit itself, since it is loaded on _{она βχ} . The nature of these changes is such that they contribute to the restoration of complete phasing in the oscillator and increase the power transmitted through the PIC circuit to excite the composite transistor, due to which the output power level again reaches its original value.

An autogenerator is an adaptive device with respect to a change in the reactive component of the external load resistance, which determines the much lower sensitivity of its output power level to such changes, and therefore, the influence of the latter on the output power level is attenuated.

Claims (1)

SUMMARY OF THE INVENTION An oscillator comprising a first transistor, between a collector and an emitter of which a first capacitor, a first inductor and a second capacitor are connected in series, a third capacitor and a second inductor, a third inductor, the first and second terminals of which are connected respectively to the base and emitter of the first transistors, fourth and fifth capacitors, as well as a power source, while the first terminal of the second inductor is connected to the first terminal of the third a capacitor, the second output of which is connected to the collector of the first transistor, characterized in that, in order to increase the level and stability of the output power when changing the parameters of the external load, a second transistor is introduced, the collector and emitter of which is connected respectively to the collector and base of the first transistor, the fourth capacitor is connected between the second terminal of the first capacitor and the common bus, the fifth capacitor is between the first terminal of the third capacitor and the common bus, the second terminal of the second inductor p It is connected to the base of the second transistor, the first and second outputs of the power source are connected respectively to the collector and the base of the second transistor, the emitter of the first transistor is connected to a common bus.