RU2461920C1 - Broadband microwave attenuator with continuous control - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: broadband microwave attenuator with continuous control contains two transmission lines with the same wave impedance, one of them is meant for microwave signal input, the other one is for output, Schottky-barrier field-effect transistor, two resistors, one of the ends of the first resistor is connected to transmission line at input, one of the ends of the second resistor is connected to transmission line at output, Schottky-barrier field-effect transistors are connected to control voltage source which contains two Schottky-barrier field-effect transistors to which also added are three resistors and inductance, drains of both Schottky-barrier field-effect transistors are connected with each other and with the other end of the second resistor, source of the first Schottky-barrier field-effect transistor is connected to the other end of the first resistor and simultaneously to one end of inductance, the other end of which is earthed, source of the second Schottky-barrier field-effect transistor is earthed, and gates of the first and the second Schottky-barrier field-effect transistors are connected to the source of control voltage through the fourth and the fifth resistors correspondingly.

EFFECT: expanding service band and reducing initial microwave losses.

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Description

The invention relates to electronic equipment, namely to microwave attenuators on semiconductor devices, namely to microwave attenuators with continuous control of attenuation of a microwave signal.

Important electrical characteristics of the microwave attenuator are the width of the working frequency band, the magnitude of the initial microwave signal loss.

Known microwave attenuator with continuous control of the attenuation of the microwave signal, containing two transmission lines with the same wave impedances, one is for the input of the microwave signal, the other for the output and the field effect transistor with a Schottky barrier (PTS).

In this case, the source of the field-effect transistor with a Schottky barrier is connected to the transmission line at the input, the drain is connected to the transmission line at the output, and the gate is connected to the control voltage source [1].

This microwave attenuator is a classic version of an electrically controlled microwave attenuator, in which a field-effect transistor with a Schottky barrier is used as an electronic key.

This microwave attenuator provides a change in the attenuation of the microwave signal depending on the control voltage, continuously changing over a wide range.

However, this microwave attenuator cannot provide a small amount of initial microwave losses and a wide working frequency band, since a field-effect transistor with a Schottky barrier has internal capacitances that vary over wide intervals when the control voltage changes.

The known microwave attenuator also with continuous control of the attenuation of the microwave signal, containing two transmission lines with the same wave impedances, one is for the input of the microwave signal, the other is for output and three field-effect transistors with a Schottky barrier, two segments of the transmission line with a length equal to a quarter of the wavelength in the transmission line, two resistors with a resistance equal to the wave resistance of the transmission line.

Moreover, each of the two field-effect transistors with a Schottky barrier, respectively, together with a segment of the transmission line and a resistor, are located on opposite sides symmetrically or non-symmetrically from the first field-effect transistor with a Schottky barrier, while the source of the field-effect transistor with a Schottky barrier is connected to the transmission line at the input, the drain - with a transmission line at the output, and the gate is connected to a control voltage source, one end of the first resistor is connected to the transmission line at the input and one end of the second resistor is connected to the transmission line at output, and the other end of the corresponding resistor through a segment of the transmission line is connected to the drain of the corresponding field-effect transistor with a Schottky barrier, the sources of which are grounded, and the gates of three field-effect transistors with a Schottky barrier are interconnected and connected to one source of control voltage [2 - prototype].

The presence of two field-effect transistors in this microwave attenuator with a Schottky barrier, each of which, together with the mentioned transmission line segments and a resistor and in combination with their indicated connection, allowed to slightly reduce the initial microwave losses.

However, this microwave attenuator, due to the presence of segments of a quarter-wavelength transmission line in it, cannot provide a significant extension of the working frequency band.

The technical result of the claimed invention is to expand the working frequency band and reduce the initial microwave losses.

The technical result is achieved by the claimed broadband microwave attenuator with continuous control, containing two transmission lines with the same wave impedances, one is for the input of the microwave signal, the other is for output, field effect transistors with a Schottky barrier, two resistors, one of the ends of the first resistor is connected to the transmission line at the input, one of the ends of the second - with a transmission line at the output, the gates of field-effect transistors with a Schottky barrier are connected to a source of control voltage.

In this case, the microwave attenuator contains two field-effect transistors with a Schottky barrier, three resistors are added to the microwave attenuator - the third, fourth, fifth and inductance, while the fourth and fifth resistors are made with equal resistances, the ends of the third resistor are connected to the transmission lines at the input and output accordingly, the drains of both field-effect transistors with a Schottky barrier are connected to each other and to the other end of the second resistor, the source of the first field-effect transistor with a Schottky barrier is connected to the other end of the first resistor and at the same time - with one end of the inductance, the other end of which is grounded, the source of the second field-effect transistor with a Schottky barrier is grounded, and the gates of the first and second field-effect transistors with a Schottky barrier are connected to the control voltage source through the fourth and fifth resistors, respectively, and the resistance value of each resistor is an order of magnitude greater than the impedance of the transmission line at the input or output of the microwave attenuator.

Disclosure of the essence.

The essential features of the claimed broadband microwave attenuator with continuous control (hereinafter referred to as the microwave attenuator), both their combination, and each separately and in combination with the stated other connection of all elements, provide the following.

The presence in the microwave attenuator of only two field-effect transistors with a Schottky barrier provides:

firstly, a decrease in the number of capacities that make up a field-effect transistor with a Schottky barrier and, as a result, an extension of the working frequency band,

secondly, a decrease in the number of resistances that make up a field-effect transistor with a Schottky barrier and, as a result, a decrease in the initial microwave losses.

The proposed inclusion of the first field effect transistor with a Schottky barrier, so that its source is connected to one of the ends of the first resistor, and its drain - to one of the ends of the second resistor provides:

firstly, the simultaneous switching on and off of these resistors,

secondly, the exclusion of the influence of the resistances of these resistors on the attenuation of the microwave signal,

and as a consequence of both, a decrease in the initial microwave losses,

thirdly, the possibility of another grounding of the ends of these resistors and thereby eliminating the dependence of the electrical resistance of the first, second and third resistors on the frequency and, as a consequence, the extension of the working frequency band.

The presence in the attenuator of the microwave inductance provides:

firstly, with the proposed connection of one of its ends to the source of the first field-effect transistor with a Schottky barrier, compensation of the capacitance of both field-effect transistors with a Schottky barrier and, as a result, the expansion of the working frequency band.

secondly, grounding the source of a field-effect transistor with a Schottky barrier by direct current through this inductance and, as a result, ensuring the possibility of operation of the first field-effect transistor with a Schottky barrier.

The presence in the microwave attenuator of the fourth and fifth resistors included in this way reduces leakage currents through the gates of field-effect transistors with a Schottky barrier and, as a result, reduces the initial microwave losses.

The claimed connection of all elements of the microwave attenuator ensures the inclusion of two field-effect transistors with a Schottky barrier in series with each other and thereby reduce their total capacitance and, as a result, expand the working frequency band.

The connection of the gates of the first and second field-effect transistors with a Schottky barrier with a control voltage source through the fourth and fifth resistors, respectively, and when the resistance of each resistor is an order of magnitude higher than the wave impedance of the transmission line at the input or output of the microwave attenuator, reduces leakage currents through the gates and, as a result, a decrease in the initial microwave losses.

In addition, the exclusion from the microwave attenuator of segments of the transmission line with a length equal to a quarter of the wavelength eliminates spurious resonances and, as a result, additional extension of the working frequency band.

The invention is illustrated by drawings.

Figure 1 gives the topology of the claimed broadband microwave attenuator with continuous control, where:

- two microwave signal transmission lines, one at the input - 1, the other at the output - 2,

- the first and second field effect transistors with a Schottky barrier - 3 and 4, respectively,

- resistors - 5, 6, 7, 8, 9, respectively,

- inductance - 10,

- source of control voltage - 11.

Figure 2 shows its electrical circuit.

Figure 3 shows the dependence of the attenuation of the microwave signal from the control voltage U, continuously changing from zero to the cutoff voltage of the field effect transistors with a Schottky barrier.

Figure 4 shows the frequency dependence of the attenuation of the microwave signal at a voltage U equal to a cutoff voltage of -2 V - the initial loss of a microwave signal, and a voltage U equal to -1.5 V, -1 V and 0 V.

An example of a specific implementation of the claimed broadband microwave attenuator with continuous control.

The microwave attenuator is made in a monolithic integral design on a semiconductor substrate of gallium arsenide with a thickness of 0.1 mm, using classical thin-film technology.

Two transmission lines intended for the input of the microwave signal 1 and for output 2 are made with the same wave impedances equal to 50 Ohms, which corresponds to a wire width of 0.08 mm.

Two field effect transistors with a Schottky barrier 3 and 4 are each made with a gate length of 0.4 μm, a gate width of 300 μm, and the same drain and source lengths of 20 μm and have a cutoff voltage of Uot. Of -2 V.

Each resistor 5, 6, 7, 8, 9 is made in the form of a tantalum film with a thickness of 4 μm and a specific resistance of 50 Ω / square.

In this case, the resistance value of the fourth and fifth resistor exceeds the wave resistance of the transmission line at the input or output of the microwave attenuator by an order of magnitude.

Inductance is made in the form of a film of gold 3 microns thick, 20 microns wide and 2 mm long.

The operating frequency band varies from 6 GHz to 18 GHz.

Wherein

- one of the ends of the first resistor 5 is connected to the transmission line at the input 1, one of the ends of the second resistor 6 is connected to the transmission line at the output 2.

- the ends of the third resistor 7 are connected to the transmission lines at input 1 and output 2, respectively

- the drains of both field effect transistors with a Schottky barrier 3, 4 are interconnected and - with the other end of the second resistor 6,

- the source of the first field-effect transistor with a Schottky barrier 3 is connected to the other end of the first resistor 5 and at the same time to one end of the inductance 10, the other end of which is grounded,

- the source of the second field-effect transistor with a Schottky barrier 4 is grounded,

- and the gates of the first and second field-effect transistors with a Schottky barrier 3, 4 are connected to the control voltage source 11 through the fourth 8 and fifth 9 resistors, respectively.

The claimed broadband microwave attenuator with continuous control of the attenuation of the microwave signal operates as follows.

When applying to the gates of field-effect transistors with a Schottky barrier 3, 4 a control voltage U of a value equal to the cut-off voltage Uot., Both field-effect transistors with a Schottky barrier become closed from the control voltage source 11.

As a result of this, both field effect transistors with a Schottky barrier each have a large Zzak resistance.

In this case, the ends of resistors 5 and 6 will be open, idle mode will be implemented at the end of resistor 6, and a large reactance from inductance 10 will be realized at the end of resistor 5, so that resistors 5 and 6 will not affect the attenuation of the microwave signal.

In this case, in a wide working frequency band the magnitude of the initial microwave losses is realized, which will be significantly less than in the prototype.

When applying to the gates of field-effect transistors with a Schottky barrier 3, 4 a control voltage U of a value equal to 0 V, both field-effect transistors with a Schottky barrier become open from the source of control voltage 11.

As a result of this, both field-effect transistors with a Schottky barrier each have a low resistance Z open.

In this case, the ends of resistors 5 and 6 will be interconnected and - with the "ground".

In this case, the maximum attenuation is realized in a wide working frequency band.

When applying to the gates of both field-effect transistors with a Schottky barrier 3 and 4 a negative control voltage U, continuously changing in the interval from Uotc. to zero, the resistance of each of the field-effect transistors with a Schottky barrier will vary from Zexc. to Z close

In this case, the attenuation of the microwave signal will change from the magnitude of the initial losses to the maximum attenuation.

On the manufactured samples of the microwave attenuator, the attenuation values of the microwave signals were measured depending on the frequency and the varying control voltage, the results of which are given in FIGS. 3 and 4.

As seen:

From figure 3, the attenuation in the microwave attenuator varies from a value of -0.5 dB to a value of -10 dB almost linearly.

From figure 4, the initial loss in the working frequency band from 6 GHz to 18 GHz is equal to 0.7 dB, which is 1.5 times less than in the prototype.

Thus, the claimed broadband microwave attenuator with continuous control will provide in comparison with the prototype:

- an increase in the width of the working frequency band by about 2 times,

- a decrease in the magnitude of the initial microwave signal loss by about 1.5 times.

The aforementioned advantages of a broadband microwave attenuator with continuous control are especially relevant when creating miniature both individual microwave devices and, especially in monolithic integrated design, and microwave electronic devices for various purposes, including miniature phased antenna arrays.

Information sources

1. Balyko A.K., Olchev B.M., Toshchov A.A. Circuit design of an electrically controlled broadband transistor attenuator / Electronic technology. Ser. 1. Microwave technology. 1997. Vol. 1, p. 15-19.

2. RF patent №2324265 IPC Н01Р 1/22, priority 05.22.2006, publ. 05/10/2008, bull. No. 13 is a prototype.

Claims (1)

A broadband microwave attenuator with continuous control, containing two transmission lines with the same wave impedances, one for the input of the microwave signal, the other for output, field-effect transistors with a Schottky barrier, two resistors, one end of the first resistor is connected to the input transmission line, one from the ends of the second one with a transmission line at the output, the gates of field-effect transistors with a Schottky barrier are connected to a source of control voltage, characterized in that the microwave attenuator contains two field-effect transistors with a barrier Schottky, three resistors are additionally introduced into the microwave attenuator - the third, fourth, fifth and inductance, while the fourth and fifth resistors are made with equal resistances, the ends of the third resistor are connected to the transmission lines at the input and output, respectively, the drains of both field-effect transistors with the Schottky barrier are connected between themselves and with the other end of the second resistor, the source of the first field effect transistor with a Schottky barrier is connected to the other end of the first resistor and at the same time to one end of the inductance, the other end of which is flax, the source of the second field-effect transistor with a Schottky barrier is grounded, and the gates of the first and second field-effect transistors with a Schottky barrier are connected to the control voltage source through the fourth and fifth resistors, respectively, and the resistance of each resistor is an order of magnitude higher than the wave resistance of the transmission line at the input or output microwave attenuator.

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