RU2298280C1 - Transistorized microwave oscillator with electrical frequency retuning - Google Patents

Abstract

FIELD: electronic engineering.

SUBSTANCE: the transistorized microwave oscillator with an electrical frequency retuning has an active device a field-effect transistor with a gate in the form of a Schottky barrier connected according to the common-source circuit, two film resistors with resistance R1 and R2 respectively. The second field-effect transistor with a gate in the form of a Schottky barrier also connected according to the common-source circuit is used as the voltage-controlled semiconductor device. The end of the oscillatory system is connected to the drain of the second field-effect transistor, some of the ends of both film resistors are connected to the gate of the first field effect transistor, and the other ends of these film transistors are connected to the common source and the gate of the second field-effect transistor respectively, control voltage of he negative polarity is applied to the gate of the second field-effect transistor, this voltage varies within 0 to Uo, where Uo - the negative pinch-off voltage of the second field-effect transistor.

EFFECT: enhanced band of frequency retuning, and provided creation of a transistorized microwave oscillator of a monolithic modification.

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Description

The invention relates to electronic equipment, namely to microwave generators on a transistor with electrical frequency tuning.

In communication systems and radar stations, microwave generators are widely used, in which the frequency is controlled by voltage. In some cases, it is necessary to carry out frequency tuning at which the generator frequency varies from the control voltage in a wide frequency range.

A known microwave generator on a transistor with electrical frequency tuning, containing a bipolar transistor as an active device, made of a semiconductor material - silicon, and connected to it an oscillating system and a voltage-controlled semiconductor device - a varactor diode included in a two-terminal circuit [1, p. 191].

The use of a varactor diode as a voltage-controlled semiconductor device is based on the dependence of the capacitance of the varactor diode on the voltage applied to it.

The frequency tuning range of such a generator is up to 30%.

The main disadvantages of this microwave generator on a transistor:

- the low upper limit of the frequency tuning range of 6-8 GHz, which is determined by the limiting frequency of the semiconductor material - silicon,

- the impossibility of achieving a wide range of frequency tuning by a varactor diode, due to its nonlinear capacitance-voltage characteristic, which has a certain (uncontrolled) law of capacitance variation, depending on one voltage.

A known microwave generator on a transistor with electric frequency tuning - a prototype containing a field-effect transistor with a gate in the form of a Schottky barrier as an active device made of a semiconductor material - gallium arsenide, an oscillating system connected to it and a voltage-controlled semiconductor device, while the field-effect transistor connected according to the circuit with a common source, one end of the oscillatory system is connected to the gate of the field-effect transistor, and the other to a voltage-controlled semiconductor device, in the quality of which is the same as in the first analogue, a varactor diode [1, p. 193].

The use of a microwave transistor with a gate in the form of a Schottky barrier in this generator, made of a semiconductor material of group A ^III B ^V - gallium arsenide, which has a higher electron mobility compared to a semiconductor material - silicon, of which a bipolar transistor is made - the active device in the previous analogue allowed to increase the lower limit of the frequency tuning range above 10 GHz.

However, the difficulty of obtaining a wide range of frequency tuning, due to the use of a varactor diode, characterized by an uncontrolled capacitance-voltage characteristic, is inherent in this design of a microwave generator on a transistor with electric frequency tuning.

In addition, it is impossible to create a monolithic microwave generator design, since a field-effect transistor with a gate in the form of a Schottky barrier and a varactor diode are made separately from different semiconductor materials.

The technical result of the invention is to increase the frequency tuning range and the possibility of creating a microwave generator on a transistor with electrical frequency tuning in a monolithic design.

The technical result is achieved by the fact that in the well-known microwave generator on a transistor with electric frequency adjustment containing an active device - a field effect transistor with a gate in the form of a Schottky barrier, made of semiconductor material of group A ^III B ^V and connected according to the circuit with a common source, the drain of which serves the output and to which voltage of positive polarity, an oscillating system and a voltage-controlled semiconductor device is applied, while one end of the oscillating system is connected to the gate in the form of a barrier A Schottky field-effect transistor, and the other with a voltage-controlled semiconductor device U, two film resistors with resistance R ₁ and R _2, respectively, are introduced into it, and a second field-effect transistor with a gate in the form of a Schottky barrier is used as a voltage-controlled semiconductor device It made also of a semiconductor material of a ^III B ^V and also connected with the common source circuit, and the other end of the oscillatory system is connected to the drain of the second field effect transistor, one of the ends of the wallpaper film resistors connected to the gate of the first field effect transistor, and the other ends of these film resistors with a resistance R ₁ and R ₂ are connected to a common source and gate as a barrier Schottky second field effect transistor, respectively, while the gate in a Schottky barrier of the second FET is supplied control voltage U of negative polarity, varying from 0 to U _o , where

U _o - negative cutoff voltage of the second field effect transistor.

The oscillation system is a separation capacitance and inductance.

The resistances R ₁ and R _{2 of the} film resistors are 80 / U _o / and 320 / U _o /, respectively.

A microwave generator on a transistor with electrical frequency tuning can be performed both in hybrid and in integral integral design.

The invention consists in the following.

The microwave generator contains two field-effect transistors with a gate in the form of a Schottky barrier made of a semiconductor material - gallium arsenide, connected according to the scheme with a common source, and one of them - the first - is used to obtain generation at a frequency f and a given output power realized using voltage of positive polarity supplied to the drain of the first field-effect transistor, and the other as the second as a semiconductor device controlled by voltage U serves to obtain generation at a frequency f. The total capacitance of a second field-effect transistor with a gate in the form of a Schottky barrier depends on two voltages - on the drain and gate in the form of a Schottky barrier of a second field-effect transistor, in contrast to a varactor diode, the capacitance of which, as mentioned above, depends on only one voltage.

The presence in the proposed design of the generator of microwave microwave film resistors with resistances R ₁ and R ₂ and the proposed other connection of structural elements in combination with a more complex functional dependence on the voltages of the full capacitances of the first and second field-effect transistors than the varactor diode allows you to set these values of these voltages U and 0.8 U, respectively, in which the frequency tuning range of the generator increases by 1.5 times or more.

When applying the control voltage U of negative polarity to the gate in the form of a Schottky barrier of the second field-effect transistor, which is changed in the range from 0 to U _o and, accordingly, when the control voltage of negative polarity on the first field-effect transistor is 0.8 U, varying in the range from 0 to 0, 8 U _o , the capacitance-voltage characteristics of the total capacitances of the first and second field-effect transistors vary from the magnitude of the above control voltages so that the frequency tuning range of the microwave generator increases by more than 1.5 times.

Changing the control voltage U of negative polarity more than U _o leads to the current cutoff of the second field effect transistor.

The change in the control voltage of negative polarity at the first field-effect transistor is limited to 0.8 U _o , since with a lower limit value the required interval for changing the total capacitance of the first field-effect transistor is not achieved, and with a larger limit value, current cutoff occurs on it. Accordingly, the resistances R ₁ and R _{2 of the} film resistors are taken so as to provide a limit value of the control voltage of negative polarity at the first field effect transistor equal to 0.8 U _o .

The invention is illustrated by drawings:

figure 1 shows one of the options for a microwave generator on a transistor with electrical frequency tuning, where

- active device - field effect transistor - 1 s

shutter in the form of a Schottky barrier - 2, s

common source - 3,

runoff - 4,

- oscillatory system - 5, which is a

separation capacity - 11 and

inductance - 12,

- voltage controlled semiconductor device U -

second field effect transistor - 6 s

shutter in the form of a Schottky barrier - 9, connected according to the scheme with

common source - 3, and

runoff - 10,

- film resistors - 7, 8 with a resistance of R ₁ and R _2, respectively.

Figure 2 shows the dependence of the frequency of the generator f on the control voltage U.

Example 1

As an example, a variant of a microwave generator on a transistor with electrical frequency tuning in a monolithic integral design is considered.

The microwave generator is made on a substrate of a semiconductor material - gallium arsenide with a thickness of 0.1 mm. On the semiconductor substrate using the operations of electron beam lithography perform the topology of the microwave generator.

In this case, the gate in the form of a Schottky barrier 2 of the first field-effect transistor 1 is connected according to the circuit with a common source 3 and to the oscillation system 5 in the form of a separation capacitance 11 of a value equal to 20 pF, which is connected to an inductance 12 of 1 nH. The inductance 12 of the oscillatory system 5 is connected to the drain 10 of the second field-effect transistor 6, a film resistor 7 with a resistance R ₁ of 200 Ohms, one end is connected to the gate in the form of a Schottky barrier 2 of the first field-effect transistor 1, and the other end to a common source 3, a film resistor 8 with a resistance of R ₂ equal to 800 Ohms, one end connected to a gate in the form of a Schottky barrier 2 of the first field effect transistor 1, and the other end to a gate in the form of a Schottky barrier 9 of the second field effect transistor 6.

Examples 2-3.

Analogously to example 1, a microwave generator was made on a transistor with electrical frequency tuning in a monolithic integral design, but with the film resistors R ₁ and R ₂ equal to 160 Ohms and 640 Ohms, respectively (example 1), 240 Ohms and 960 Ohms, respectively (example 2 )

The device operates as follows.

A voltage of positive polarity +6 V is applied to drain 4 of the first field-effect transistor 1 with a gate in the form of a Schottky 2 barrier. A voltage of negative polarity 6 is applied to the gate in the form of a Schotky barrier 9 of a second field-effect transistor 6, which varies from 0 to a negative cutoff voltage equal to 2.5 V. The resistance of the film resistors R ₁ and R ₂ for the above negative cut-off voltage is 200 and 800 Ohms, respectively. In this case, the control voltage of negative polarity, varying from 0 to - 2.0 V., will accordingly be supplied to the gate in the form of a Schottky barrier 9 of the second field-effect transistor.

As can be seen from figure 2, the frequency f of the microwave generator varies from 10 GHz to 16 GHz, which is illustrated by curves 1, 2, 3, respectively, examples 1, 2, 3.

Thus, the proposed design of the microwave generator in comparison with the prototype will allow:

- firstly, significantly expand the frequency tuning range, more than 1.5 times,

- secondly, to realize the possibility of performing a microwave generator in both hybrid and monolithic integral design, since it contains two field-effect transistors with a gate in the form of a Schottky barrier, which can be performed in a single technological cycle on one semiconductor substrate.

The source of information

1. Solid-state microwave devices in communication technology. L.G. Gassanov, A.A. Lipatov, V.V. Markov. - M .: Radio and communications, 1988.

Claims (4)

1. A microwave generator on a transistor with electric frequency tuning, containing an active device - a field effect transistor with a gate in the form of a Schottky barrier, made of a semiconductor material of group A ^III B ^V and connected according to the circuit with a common source, the drain of which serves as an output and to which voltage is applied of positive polarity, an oscillatory system and a voltage-controlled semiconductor device, while one end of the oscillating system is connected to the gate in the form of a Schottky field-effect transistor, and the other to a semiconductor a voltage-controlled device, characterized in that two film resistors with resistance R1 and R2, respectively, are introduced into it, and a second field-effect transistor with a gate in the form of a Schottky barrier, also made of a semiconductor material of the group, is used as a voltage-controlled semiconductor device A ^III B ^V and connected also according to the scheme with a common source, and the other end of the oscillating system is connected to the drain of the second field-effect transistor, one ends of both film resistors are connected to the gate rum of the first field-effect transistor, and the other ends of these film resistors are connected to a common source and to the gate in the form of a Schottky barrier of the second field-effect transistor, respectively, while the control voltage of negative polarity, varying from 0 to U _o , where U _o is the negative cutoff voltage of the second field effect transistor. 2. A microwave generator on a transistor with electrical frequency tuning according to claim 1, characterized in that the oscillating system is a separation capacitance and inductance. 3. A microwave generator on a transistor with electrical frequency tuning according to claim 1, characterized in that the generator is made in a hybrid integrated design. 4. A microwave generator on a transistor with electrical frequency tuning according to claim 1, characterized in that the generator is made in a monolithic integral design.

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