RU2517722C1 - Shf protective device - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: SHF protective device contains the central conductor, the first and second section of the transmission line, the first and second semiconductor devices, the first, second and third resistors and two inductance coils. Both sections of the transmission line are made as sections of the single transmission line, each having a length equal to one eighth of the wave length in the transmission line section within the central frequency of the service band and a wave impedance equal to the wave impedance of the central conductor, Schottky-barrier field-effect transistors are used as semiconductor devices, the first and third transistors are similar and have an impedance to the order higher than the wave impedance of the central conductor.

EFFECT: increase of permitted input power, expansion of the service band of frequency, reduction of SHF direct losses.

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Description

The invention relates to electronic equipment, namely to microwave protective devices on semiconductor devices.

The main parameters of the microwave protection device are:

- working frequency band,

- direct microwave losses in its open state,

- permissible input power or module attenuation coefficient of the microwave signal in the closed state.

A microwave protective device is known, comprising a central conductor and a semiconductor device — a pin diode, in which the pin diode is connected directly to the center conductor [1].

The disadvantages of this microwave protection device are:

large direct losses, since a pin diode connected directly to the transmission line has a relatively large microwave power loss,

narrow working frequency band, since the pin diode has a capacitive reactance,

and poor protection of the pn diode from direct exposure to microwave power.

A microwave protective device is known, comprising a central conductor, a segment of a transmission line connected to it, and a pin diode located at the end of the transmission line.

In which, in order to increase the allowable input power, a resistor is additionally introduced, and the segment of the transmission line is made in the form of two connected lines, a pin diode is located at the end of one line, and a resistor connected parallel to the pin diode is located at the end of the line, while the length of the connected lines is equal to

l = λ ₀ × (2k + 1) / 4,

Where

λ ₀ - wavelength at the center frequency,

k = 0, 1, 2, ... [2] is the prototype.

Due to the inclusion of a pin diode in the central conductor through a segment of the transmission line, this microwave protective device has made it possible to slightly reduce direct losses and protect the pin diode from direct exposure to microwave power.

However, the use of a segment of connected transmission lines

firstly, a narrow working frequency band, and

secondly, large direct losses and especially in the range of millimeter wavelengths.

The technical result of the claimed invention is to increase the allowable input power, expand the working frequency band and reduce direct microwave losses.

The technical result is achieved by the claimed microwave protective device containing a central conductor, one end of which is intended for the input of the microwave signal, the other is for output, a segment of a transmission line connected to it, a semiconductor device connected to the other end of a segment of a transmission line, a resistor.

A second segment of the transmission line, a second semiconductor device, two identical inductances, two identical resistors, are additionally introduced into the protective device

in this case, both segments of the transmission line are made in the form of segments of a single transmission line, each with a length equal to one eighth of the wavelength in the segment of the transmission line at the central frequency of the working frequency band, and wave impedance equal to the wave impedance of the central conductor,

as semiconductor devices, field-effect transistors with a Schottky barrier are used,

the magnitude of each inductance L (H) is equal to

, $$L=\mathrm{one}-\left(\mathrm{four}\times {\mathrm{<figure-callout\; id="2"\; label="\pi "\; filenames="00000007.png"\; state="\{\{state\}\}">\pi </figure-callout>}}^2\times f_0^2\times C_T\right)$$

,

Where

C _T - output capacitance of a field effect transistor with a Schottky barrier, F,

π is a number equal to 3.1415,

f ₀ - the center frequency of the working frequency band, Hz,

the first resistor is made with a resistance R (Ohms) equal to

R = 60 × [exp (-0.2 × Az) -1],

Where

Az - the module of a given amount of attenuation at the central frequency of the working frequency band, dB;

exp (x) is an exponential function of the argument x,

the same second and third resistors are made with resistance, an order of magnitude greater than the wave impedance of the Central conductor,

wherein one end of the first inductance is connected to the drain of the first field-effect transistor with a Schottky barrier and to the other end of the first segment of the transmission line, its other end is connected to its source and to one end of the second segment of the transmission line, its other end is connected to the drain of the second field-effect transistor with the Schottky barrier and with one end of the second inductance and the first resistor, the other ends of which are grounded, the source of the second field-effect transistor with the Schottky barrier is grounded, the gate of each field-effect transistor with the Schottky barrier is connected through the identical second and third resistors, respectively, to a source of constant voltage control.

Disclosure of the invention.

The set of essential features of the claimed microwave protection device, namely:

Introduction to the microwave protection device of the second semiconductor device will allow you to redistribute the input power between the two semiconductor devices and thereby increase the allowable input power of the microwave protection device.

And the use as each semiconductor device of a field effect transistor with a Schottky barrier, which is compared with a pin diode

firstly, it is a wider semiconductor device due to the presence of the third electrode - the gate and the associated distribution of the capacitance between the three electrodes into the components included inside the device in a parallel-serial circuit, which ultimately leads to a decrease in the total internal capacitance and, as a result, the expansion of the working frequency band of the microwave protection device,

secondly, it has significantly lower internal resistances, and especially in the millimeter wavelength range due to the use of a semiconductor material - gallium arsenide, which has higher mobility compared to silicon, of which the pin diode is made, and, as a result, a decrease in direct losses microwave protection device.

Introduction to the microwave protection device of the second segment of the transmission line and its sequential inclusion of the first and second field-effect transistors with a Schottky barrier will ensure the serial connection of field-effect transistors with a Schottky barrier, necessary for the redistribution of input power between two field-effect transistors with a Schottky barrier and, as a result, an increase in the permissible input power microwave protection device.

Transmission line segments

firstly, in the form of segments of a single transmission line, instead of a segment of coupled transmission lines, it will ensure the elimination of irretrievable power losses due to coupled transmission lines, the communication area in which is open for the emission of electromagnetic waves into space and, as a result, a decrease in direct losses of the microwave protection device of the microwave ,

secondly, with a length equal to one-eighth of the wavelength at the middle frequency of the working frequency band, it will provide a separation of resonant frequencies from the average frequency of the working frequency band and, as a result, reducing the direct microwave losses and expanding the working frequency band of the microwave protection device, and

thirdly, the value of wave impedance equal to the value of wave impedance of the central conductor will provide better coordination between transmission lines with the same wave impedances, as well as eliminating the influence of inhomogeneities that occur at the junction of the first segment of the transmission line and the central conductor and, as a result, reducing the value direct microwave losses.

The introduction into the microwave protection device of two inductors with their indicated values, each of which is connected in parallel with the corresponding field-effect transistor with a Schottky barrier, will provide in the working frequency band

firstly, the compensation of the output capacitance of a field effect transistor with a Schottky barrier and

secondly, the coordination of its internal resistance with the wave impedance of the central conductor and thereby the realization of the optimal values of the parameters of the microwave protection device and, as a result, the expansion of the working frequency band and the reduction of direct microwave losses.

The first resistor, made with the specified resistance value, will allow to realize the optimal values of the parameters of the microwave protection device and, as a result, increase the permissible input power, expand the working frequency band and reduce the direct microwave losses.

The introduction of two additional identical second and third resistors, included in the corresponding gate circuits of two field-effect transistors with a Schottky barrier, will significantly reduce the leakage currents through the gates of field-effect transistors with a Schottky barrier and, as a result, reduce the magnitude of direct microwave losses.

So, as can be seen from the foregoing, the proposed set of essential features of a microwave protection device will fully provide the technical result indicated above, namely, an increase in the allowable input power, an expansion of the working frequency band and a decrease in direct microwave losses.

The invention is illustrated by drawings.

Figure 1 gives the topology of the claimed microwave protection device,

Where

- the central conductor - 1, one end of which is intended for the input of the microwave signal - 2, the other - for the output - 3,

- the length of the transmission line is 4,

- semiconductor device - field effect transistor with a Schottky barrier - 5,

- the first resistor is 6,

- the second segment of the transmission line is 7,

- the second semiconductor device is a field effect transistor with a Schottky barrier - 8,

- two identical inductances - 9, 10, respectively,

- the same second and third resistors - 11, 12, respectively,

- source of control direct voltage -13.

Figure 2 shows its circuit diagram.

Figure 3 shows the dependence on the frequency of direct microwave losses.

Figure 4 shows the dependence on the frequency of the module attenuation coefficient.

An example of a specific implementation of the claimed microwave protection device.

All elements of the microwave protection device are made in integral integral design on a semiconductor substrate of gallium arsenide with a thickness of 0.1 mm using the classic thin-film technology.

The Central conductor 1 is made of the same width equal to 0.08 mm (50 Ohms).

The segments of the transmission line 4, 7 are each 0.35 mm long and 0.08 mm wide, which corresponds to a length equal to one eighth of the wavelength in the segment of the transmission line at the central frequency of the working frequency band, and the wave impedance equal to twice the wave impedance of the central conductor (50 ohms).

Semiconductor devices 5, 8 are made in the form of a field effect transistor with a Schottky barrier.

The first resistor 6 is made with a resistance R equal to 180 Ohms (according to the expression R = 60 × [exp (-0.2 × Az) -1] with Az equal to -8 dB).

для центральной частоты рабочей полосы частот - 36 ГГц).Both identical inductances 9, 10 are made with L equal to 0.5 nH (according to the expression $$L=\mathrm{one}-\left(\mathrm{four}\times {\mathrm{<figure-callout\; id="2"\; label="\pi "\; filenames="00000007.png"\; state="\{\{state\}\}">\pi </figure-callout>}}^2\times f_0^2\times C_T\right)$$

for the central frequency of the working frequency band - 36 GHz).

Wherein

one end of the first inductance 9 is connected to the drain of the first field-effect transistor with a Schottky barrier 5 and to the other end of the first segment of the transmission line 4, its other end is connected to its source and to one end of the second segment of the transmission line 7, its other end is connected to the drain of the second field a transistor with a Schottky barrier 8 and with one end of the second inductance 10 and the first resistor 6, the other ends of which are grounded, the source of the second field-effect transistor with a Schottky barrier is grounded, the gate of each field-effect transistor with a Schottky barrier 5, 8 is connected ene via respective identical second 11 and third resistors 12 to a source of constant voltage control 13.

The microwave protection device operates as follows.

When each field-effect transistor with a Schottky barrier 5 and 8 is supplied to the gate from a source of control direct voltage 13 of a voltage of 0 V, each field-effect transistor with a Schottky barrier opens, a direct current flows through it.

In this case, the total resistance Z _T between the drain and the source of each field-effect transistor with a Schottky barrier will be resistive and its value will be significantly (two orders of magnitude) lower than the resistance R of the first resistor 6, so that the resistance of this resistor connected in parallel with the small resistance Z _{T of the} second field-effect transistor with a Schottky barrier 8 will not affect the operation of the microwave protection device.

Inductance due to additionally introduced the same inductances 9 and 10 with their declared values in the working frequency band are compensated by segments of the transmission line 4 and 7 with their declared lengths and wave impedances.

The small resistance of the first field-effect transistor with a Schottky barrier 5 shorts the second end of the length of the transmission line 4 and the first end of the second length of the transmission line 7. The total length of the lengths of the transmission line will be equal to the sum of their lengths, that is, with the declared values of the lengths of the lengths of the transmission line - a quarter of the length waves in the transmission line.

In this case, the total resistance of the first resistor 6 and the parallel connected low resistance of the second field-effect transistor with a Schottky barrier 8, transformed to the central conductor 1 parallel to the input 2 and output 3 of the microwave protection device, will be as large as possible and thereby the direct microwave losses will be minimal.

When each field-effect transistor with a Schottky barrier 5 and 8 is supplied to the gate from a source of control constant voltage 13, a voltage equal to the cut-off voltage is minus 2.5 V, field-effect transistors with a Schottky barrier will close, and no direct current will flow through them.

In this case, the resistance Z _T between the drain and the source of each field-effect transistor with a Schottky barrier will be capacitive in nature. These resistances in the working frequency band are compensated by:

firstly, inductive resistances of the corresponding inductance 9 and 10 with the declared value,

secondly, the corresponding segment of the transmission line 4 and 7 with their stated length and impedance.

In this case, the resistance of the first resistor 6 at the other end of the second segment of the transmission line 7 is transformed through this segment of the transmission line and the first segment of the transmission line 4 to the central conductor 1 parallel to the input 2 and output 3 of the microwave protection device to a value that provides a given value of the attenuation coefficient module on the central frequency of the working frequency band.

On the manufactured samples of the microwave protection device were measured:

depending on the frequency of direct microwave losses (Fig. 3) and on the frequency of the module of the attenuation coefficient (Fig. 4).

As can be seen from figure 3 and 4 of the claimed microwave protection device will provide:

- the ability to work in the eight millimeter wavelength range (31-41 GHz),

- extension of the working frequency band to 10 GHz,

- reduction of direct microwave losses to 0.6 dB,

- an increase in the allowable input power by about 2 times (increase in the attenuation coefficient module by about 1.4 times).

Thus, the claimed microwave protection device will allow, in comparison with the prototype, to expand the operating frequency band by about 1.5 times, reduce direct microwave losses by about 1.3 times, and increase the allowable input power by about 2 times.

Information sources

1. Weissblat A.V. Microwave switching devices on semiconductor diodes. // M: Radio and communications. - 1987. - P.45.

2. RF patent No. 2189670. Priority 08.08.2001 Publ. September 20, 2002 Bull. No. 26 is a prototype.

Claims (1)

Microwave protective device containing a central conductor, one end of which is intended for microwave signal input, the other is for output, a transmission line segment connected to it, a semiconductor device connected to the other end of a transmission line segment, a resistor, characterized in that a second segment of the transmission line, a second semiconductor device, two identical inductances, two identical resistors are additionally introduced into the protective device, while both segments of the transmission line are made in the form of segments of a single transmission line, each with a length equal to one eighth of the wavelength in the segment of the transmission line on the central frequency of the working frequency band, and wave impedance equal to the impedance of the central conductor, field-effect transistors with a Shot barrier are used as semiconductor devices ki, with each inductance equal to

,
Where
L is the magnitude of each inductance, H,
C_T - output capacitance of a field effect transistor with a Schottky barrier, F,
π is a number equal to 3.1415,
f₀ - the center frequency of the working frequency band, Hz,
the first resistor is made with a resistance equal to
R = 60 × [exp (-0.2 × Az) -1],
Where
R is the resistance of the first resistor, Ohm,
Az - the module of a given amount of attenuation at the central frequency of the working frequency band, dB;
exp (x) is an exponential function of the argument x,
identical second and third resistors are made with a resistance an order of magnitude greater than the wave impedance of the central conductor, while one end of the first inductance is connected to the drain of the first field-effect transistor with a Schottky barrier and to the other end of the first segment of the transmission line, its other end is connected to its source and one end of the second segment of the transmission line, its other end is connected to the drain of the second field-effect transistor with a Schottky barrier and with one end of the second inductance and the first resistor, the second ends of which grounded, the source of the second field-effect transistor with a Schottky barrier is grounded, the gate of each field-effect transistor with a Schottky barrier is connected through the same second and third resistors, respectively, to a source of control DC voltage.

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