RU2517429C1 - Voltage-controlled generator - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: voltage-controlled generator comprises two field-effect transistors, five inductance coils, seven capacitors, a conducting bias circuit, an automatic cutoff bias circuit, a control circuit and an external load.

EFFECT: wider range of operating frequencies and frequency stability of generated oscillations.

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Description

The invention relates to the field of radio engineering and can be used as a source of high-frequency oscillations in radio transmitting, radio receiving devices and measuring equipment.

The closest in technical essence of the claimed device is a voltage-controlled generator [1], containing a self-oscillator, including a first inductor, the first output of which is connected to a power source, a first capacitor, a first field effect transistor (PT), the drain of which is connected to the first output of the first a capacitor and a second terminal of a first inductor, and a second terminal of a first capacitor is connected to a common point, a second capacitor, a third capacitor, a fourth capacitor and a second the inductance carcass, the first terminal of the second capacitor connected to the first terminal of the third capacitor, the second terminal of the third capacitor connected to the first terminal of the fourth capacitor, the second terminal of the second capacitor connected to the first terminal of the second inductor and the gate of the first PT, the second terminal of the fourth capacitor connected to the second the output of the second inductor, the second output of the third capacitor and the first output of the fourth capacitor are connected to a common point, the fifth capacitor, the first the first output of which is connected to the second output of the fourth capacitor, a gate bias circuit consisting of a first resistor, a second resistor and a third inductor, while the first output of the first resistor is connected to the second output of the first inductor, the connection point of the first resistor and second resistor is connected to the first the output of the third inductor, the locking circuit bias, including the fourth inductor and the third resistor connected in series, the sixth cond nsator and external load, while the first terminal of the fourth inductor is connected to the source of the first PT and the first terminal of the sixth capacitor, the second terminal of the sixth capacitor is connected to the first terminal of the external load, and the second terminal of the external load and the second terminal of the third resistor are connected to a common point, the circuit a control comprising a fifth inductor magnetically coupled to the second inductor, and a seventh capacitor, the first terminal of which is connected to the first terminal of the fifth inductor, and the second the output of the seventh capacitor is connected to a common point, a second transformer with a terminal of a TIR type substrate is introduced, the drain and source of the second transformer with a terminal of a TIR type substrate are connected respectively to the second terminal of the fifth capacitor and a common point, and the gate of the second terminal with a terminal of TIR type substrate is connected to the second output of the fifth inductance coil, a bias voltage source, the first electrode of which is connected to the substrate of the second MOSFET type transformer, and the second bias voltage source electrode is connected to a common point, while the output of the device wa is the first terminal of the external load.

A disadvantage of the known device is the low operating frequency range and the stability of the frequency of the generated oscillations.

This is due to the fact that in the bipolar transistor (BT) of the diode-transistor switch, when it is open (the base-emitter junction is open), charge accumulation occurs, which leads to the appearance of a large diffusion capacitance. Therefore, even at relatively low frequencies, which are units of megahertz, a considerable inertia appears in the microwave and high-frequency BTs, leading to an increase in the time of its inclusion and phase shifts. With increasing frequency, the inertia increases rapidly, which leads to the appearance of significant losses in the BT and, accordingly, to a decrease in the range of operating frequencies and the stability of the frequency of the generated oscillations.

The invention is aimed at increasing the range of operating frequencies and frequency stability of the generated oscillations.

This is achieved by the fact that in the voltage-controlled generator containing a self-oscillator, including a first inductor, the first output of which is connected to a power supply source, a first capacitor, a first field effect transistor (PT), the drain of which is connected to the first output of the first capacitor and the second output of the first inductors, and the second terminal of the first capacitor is connected to a common point, the second capacitor, the third capacitor, the fourth capacitor and the second inductor, while the first output of the second the capacitor is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the first terminal of the fourth capacitor, the second terminal of the second capacitor is connected to the first terminal of the second inductor and the gate of the first PT, the second terminal of the fourth capacitor is connected to the second terminal of the second inductor, the second terminal of the third the capacitor and the first terminal of the fourth capacitor are connected to a common point, the fifth capacitor, the first terminal of which is connected to the second terminal of the four of the capacitor, a gate bias circuit consisting of a first resistor, a second resistor and a third inductor, wherein the first terminal of the first resistor is connected to the second terminal of the first inductor, the connection point of the first resistor and second resistor is connected to the first terminal of the third inductor, the locking circuit automatic bias, including a fourth inductor and a third resistor connected in series, a sixth capacitor and an external load, with the first output through a twisted inductance coil is connected to the source of the first PT and the first terminal of the sixth capacitor, the second terminal of the sixth capacitor is connected to the first terminal of the external load, and the second terminal of the external load and the second terminal of the third resistor are connected to a common point, the control circuit containing the fifth inductor is magnetically connected to the second inductor, and a seventh capacitor, the first terminal of which is connected to the first terminal of the fifth inductor, and the second terminal of the seventh capacitor is connected to a common a point, a second PT is introduced with the output of the MIS type substrate, and the drain and source of the second PT with the output of the MIS type substrate are connected respectively to the second output of the fifth capacitor and the common point, and the gate of the second PT with the output of the MIS type substrate is connected to the second output of the fifth inductor, a bias voltage source, the first electrode of which is connected to the substrate of the second MOSFET type PT, and the second bias voltage source electrode is connected to a common point, while the output of the device is the first output of the external load.

The drawing (Fig. 1) shows a diagram of a voltage-controlled generator. The voltage-controlled generator comprises a self-oscillator including a first inductor 1, the first terminal of which is connected to a power supply source E _p , a first capacitor 2, a first PT 3, drain 4 of which is connected to the first terminal of the first capacitor 2 and the second terminal of the first inductor 1 and the second terminal of the first capacitor 2 is connected to a common point, the second capacitor 5, the third capacitor 6, the fourth capacitor 7, and the second inductor 8, while the first terminal of the second capacitor 5 is connected to the gate ohm 9 of the first PT 3, and the second terminal of the second capacitor 5 is connected to the first terminal of the third capacitor 6, the second terminal of the third capacitor 6 is connected to the first terminal of the fourth capacitor 7, the second terminal of the second capacitor 5 is connected to the first terminal of the second inductor 8, the second terminal of the fourth the capacitor 7 is connected to the second terminal of the second inductor 8, the second terminal of the third capacitor 6 and the first terminal of the fourth capacitor 7 are connected to a common point, the fifth capacitor 10, the first terminal of which is connected connected to the second terminal of the fourth capacitor 7, a gate bias circuit consisting of a first resistor 11, a second resistor 12 and a third inductor 13, while the first terminal of the first resistor 11 is connected to the second terminal of the first inductor 1, and the connection point of the first resistor 11 and the second resistor 12 is connected to the first terminal of the third inductor 13, and the second terminal of the third inductor 13 is connected to the gate 9 of the first PT 3, a locking automatic bias circuit including the fourth coil the inductance 14 and the third resistor 15 connected in series, the sixth capacitor 17 and the external load 18, while the first terminal of the fourth inductor 14 is connected to the source 16 of the first PT 3 and the first terminal of the sixth capacitor 17, the second terminal of the sixth capacitor 17 is connected to the first terminal of the external load 18, and the second terminal of the third resistor 15 is connected to a common point, a control circuit comprising a fifth inductor 19, magnetically coupled to the second inductor 8, and a seventh capacitor 20, the first terminal of which connected to the first terminal of the fifth inductor 19, and the second terminal of the seventh capacitor 20 is connected to a common point, the second PT 21 with the output of the MIS type substrate 22 is introduced, and the drain 23 and the source 24 of the second PT 21 with the output of the MIS type substrate 22 are connected respectively to the second terminal of the fifth capacitor 10 and the common point, and the gate 25 of the second PT 21 with the output of the MIS type substrate 22 is connected to the second terminal of the fifth inductance coil 19, a bias voltage source E _b , the first electrode 26 of which is connected to the terminal output of the substrate 22 of the second MDP 21 type, and the second electrode of the bias voltage source E _{b is} connected to a common point, while the output of the device is the first output of the external load 18.

The device operates as follows. When you turn on the source of the supply voltage E _p through the first inductor 1 to the drain 4 of the first PT 3 on which the oscillator is made, the supply voltage E _p is supplied, and the gate 9 of the first PT 3 through the third inductor 13 is supplied with a biasing bias voltage generated by the first resistor 11 and the second resistor 12 from the source E _p . At the same time, a bias voltage of -E _in is applied to the output of the substrate 22 of the second PT 21 from the potential electrode 26.

By choosing the value of the feedback coefficient, determined by the values of the capacitances of the second and third capacitors 5 and 6, and the voltage of the unlocking bias on the gate 9 of the first PT 3, vibration excitation is achieved in the circuit of the oscillator formed by the capacities of the second capacitor 5, third capacitor 6, fourth capacitor 7, forming the first branch of the oscillatory circuit, and the inductance of the second inductor 8, making up the second branch of this circuit.

With increasing signal level in the circuit, the automatic bias voltage at the third resistor 15 also increases, which leads to the establishment of a stationary mode with a constant frequency ω _g and amplitude. At the same time, a frequency voltage ω _g generated on the fourth capacitor 7 is applied through the fifth capacitor 10 between the drain 23 and the source 24 of the second PT 21 with the output of the MIS type substrate 22 and, due to the magnetic coupling of the second inductor 8 with the third inductor 19, is created between the gate 25 second Fri 21 and a common point. At the same time, the RF signal taken from the third capacitor 6 of the oscillatory circuit of the oscillator, through the sixth capacitor 17 is transmitted to the output of the device.

A distinctive feature of MOS type field effect transistors from BT is, as you know, that they pass current well in the opposite direction, i.e. have two-sided conductivity. However, the manufacturing technology of MIS field-effect transistors is such that a p-n junction is formed parallel to the channel (drain-source terminals), which, at negative values of the drain current, when the voltage on the channel exceeds the cut-off voltage (E '= 0.5 ... 0.7 V), opens and therefore begins to pass current. The drain current stops when the PT closes, when the gate-source voltage becomes less than E '.

For normal operation of the key, it is necessary to ensure a mode in which a stable and fast switching of the PT occurs. For this purpose, a negative locking bias voltage -E _b is supplied to the output of the substrate 22 of the second PT 21 for an MIS transistor with an n-channel (Fig. 1). In the case of using a PT with a p-channel, a blocking voltage + E _b is applied to its substrate. In both cases, the bias voltage modulo should exceed E 'by approximately an order of magnitude. This ensures stable switching of the transistor in both directions and with low inertia. Therefore, an MIS type PT is a double-acting high-frequency key, since its inertia begins to manifest itself at frequencies above 40 ... 50% of its cutoff frequency.

Thus, in the inventive device, a double-acting controlled key can be implemented with a significantly higher upper cut-off frequency compared to the diode-transistor key presented in [1].

Together with the capacity of the fifth constant capacitor 10, this switch with two-sided conductivity and its control circuit, formed by the fifth inductor 19, magnetically coupled to the second inductor 8, and the seventh capacitor 20, form a controlled capacitance.

The frequency control of the generated oscillations ω _{g is} controlled by applying a control voltage E _y to the input of the device and is based on a change in the controlled capacitance [1]

$${\mathrm{FROM}}_{\mathrm{at}}={\mathrm{FROM}}_0-{\pi }^{-\mathrm{one}}(\alpha -\sin \alpha \cdot \cos \alpha ){\mathrm{FROM}}_0,(\mathrm{one})$$

where C ₀ is the capacity of the fifth (linear) capacitor C10;

$$\cos \alpha =(E_{\mathrm{at}}-E\text{'}\text{'})/U_{oc},(2)$$

where U _oc is the voltage amplitude between the gate 25 of the second PT 21 and the common point.

With the simultaneous action of a control and high-frequency voltage of purity ω _g , between the gate 25 of the PT21 type MIS and the common point, the fifth capacitor 10 is periodically connected to the fourth capacitor 7. The change in E _y leads to a change in the equivalent capacitance and frequency of the high-frequency oscillations over a wide range.

The frequency of the generated oscillations is determined by the expression [1]

$${\omega }_g=P{\{({\mathrm{FROM}}_{\mathrm{at}}+{\mathrm{FROM}}_{\mathrm{one}}+{\mathrm{FROM}}_E)/[L_K({\mathrm{FROM}}_{\mathrm{at}}+{\mathrm{FROM}}_{\mathrm{one}}){\mathrm{FROM}}_E]\}}^{0.5},(3)$$

where C ₁ is the capacity of the third capacitor 7;

$${\mathrm{FROM}}_E=({\mathrm{FROM}}_2+{\mathrm{FROM}}_{3\mathrm{AND}})({\mathrm{FROM}}_3+{\mathrm{FROM}}_{\mathrm{FROM}\mathrm{AND}})/({\mathrm{FROM}}_2+{\mathrm{FROM}}_{3\mathrm{AND}}+{\mathrm{FROM}}_3+{\mathrm{FROM}}_{\mathrm{FROM}\mathrm{AND}}),(\mathrm{four})$$

where C ₂ is the capacity of the second capacitor 5; C ₃ - the capacity of the third capacitor 6; With _CI , C _SI - the capacity of the first PT 3; L _K - inductance of the second inductor 8.

Along with this, when a modulating voltage of sound frequencies is applied to the input of the device, linear frequency modulation is also realized, which is due to the linearity of the modulation characteristic (3). In this case, by selecting both the capacitance C _{0 of the} fifth capacitor 10 and the bias voltage E _b on the substrate of the second PT21, the slope of the modulation characteristics can be controlled.

To increase the stable operation of the voltage-controlled generator, the first inductor 1 is interlocked (with high resistance for frequency fluctuations ω _g ). The first capacitor 2, the sixth and seventh capacitors 17, 20 are blocking, but their resistance is chosen to be much lower, at least an order of magnitude, compared with the wave resistance of the oscillator circuit of the oscillator and the resistance of the external load 18, respectively. As a result, the capacitance of the first capacitor 2 achieves the grounding of the drain 4 of the first PT 3 at a high frequency and ensures the stability of excitation and operation. The sixth capacitor 17 eliminates the passage of direct voltage to the external load 18.

To reduce the shunting effect of the third resistor 15 of the oscillatory circuit, which can occur due to the parallel connection of the third resistor 15 and the third capacitor 6, which is an element of the oscillator circuit, a fourth inductor 14 is turned on, which increases the resistance of the source 16 of the first PT 3 to the high frequency of the branch point.

In many cases, it is advisable to use not a field-effect transistor, as shown in the drawing, but a VT, which due to the significantly greater steepness of the pass-through characteristic when the generated powers are equal, ensures the excitation and operation of the device when the external load changes, as an active element that provides self-oscillation of self-oscillation, supply voltage and during operation. In addition, PTs, unlike BTs, are subject to static electricity, which impairs the reliability of the device.

However, the use of a PT is justified, for example, in those cases where it is necessary to reduce the level of undesirable oscillations at the output of the device, and in some cases to improve the conditions for matching the equivalent circuit resistance with the internal resistance of the transistor, especially with increasing generated power and frequency.

The voltage-controlled generator is implemented in practice, since domestic PTs are known, for example, KP 907, KP908, KP909 and others [3], which have a separate substrate output, which in this case is the fourth electrode, a small (several Ohms) saturation resistance, and therefore can be used as a double-acting managed key. The cutoff frequency of these transistors is about one GHz. It is possible to implement the inventive device in the VHF range in the form of a hybrid integrated circuit and on more modern transformers.

In addition, PT compared with BT have large input and output resistances. Therefore, the use of PTs both as an active element in the excitation of oscillations, and as a double-acting controlled key in a voltage-controlled generator circuit, leads to a smaller change in the quality factor of the oscillating circuit and, with the equality of the structural quality factor of the circuits and external load resistances, provides greater frequency stability fluctuations.

Compared with when varactors (varicaps) are used as a frequency controller, the inventive device achieves a constant modulation characteristic slope in a wide range of operating frequencies and creates a significantly higher level of RF power in an external load.

INFORMATION SOURCES

1. Bocharov M.I. The use of synthesized nonlinear reactive elements for controlling the frequency of oscillators / M.I. Bocharov, M.V. Klykov, O. P. Novozhilov // Radio Engineering, 1987. No. 4. S.21-23.

2. Razevig V.D. Systems for end-to-end design of electronic devices Design - Lab 8.0 / V.D. Razevig, 1999. - 699 p.

3. Semiconductor devices. Transistors of large and medium power: Reference / A.A. Zaitsev, A.I. Mirkin, V.V. Mokryakov and others; under the editorship of A.V. Golomedova. - M.: Radio and Communications, 1989 .-- 640 p.

Claims (1)

A voltage controlled oscillator comprising an oscillator including a first inductor, the first terminal of which is connected to a power supply source, a first capacitor, a first field effect transistor (PT), the drain of which is connected to the first terminal of the first capacitor and the second terminal of the first inductor, and the second terminal the first capacitor is connected to a common point, the second capacitor, the third capacitor, the fourth capacitor and the second inductor, while the first output of the second capacitor is connected to the first terminal of the third capacitor, the second terminal of the third capacitor is connected to the first terminal of the fourth capacitor, the second terminal of the second capacitor is connected to the first terminal of the second inductor and the gate of the first PT, the second terminal of the fourth capacitor is connected to the second terminal of the second inductor, the second terminal of the third capacitor and the first the output of the fourth capacitor is connected to a common point, the fifth capacitor, the first output of which is connected to the second output of the fourth capacitor, the circuit from a bias bias consisting of a first resistor, a second resistor and a third inductor, wherein the first terminal of the first resistor is connected to the second terminal of the first inductor, the connection point of the first resistor and second resistor is connected to the first terminal of the third inductor, a locking bias circuit including the fourth inductor and the third resistor connected in series, the sixth capacitor and the external load, while the first output of the fourth coil is inductive the bridge is connected to the source of the first PT and the first terminal of the sixth capacitor, the second terminal of the sixth capacitor is connected to the first terminal of the external load, and the second terminal of the external load and the second terminal of the third resistor are connected to a common point, the control circuit containing the fifth inductor magnetically coupled to a second inductor, and a seventh capacitor, the first terminal of which is connected to the first terminal of the fifth inductor, and the second terminal of the seventh capacitor is connected to a common point, characterized in that a second PT is introduced with an MIS type substrate terminal; moreover, the drain and source of a second DT with an MIS type substrate terminal are connected respectively to the second terminal of the fifth capacitor and a common point, and the gate of the second DT with terminal MIS type substrate is connected to the second terminal of the fifth inductor, voltage source bias, the first electrode of which is connected to the substrate of the second MOSFET type FET, and the second electrode of the bias voltage source is connected to a common point, while the output of the device is the first output of the external load.