JPH07249963A - Driving circuit for attenuation element - Google Patents

Abstract

PURPOSE:To more accurately execute distortion compensation for compensating the non-linear characteristic of an attenuation element. CONSTITUTION:Fifteen kinds of digital control data previously set up by switches 61-1 to 61-7 are alternatively outputted by a count value of a pulse counter which corresponds to an external command. The outputted digital control data are converted into analog voltage by a D/A converter 7 to control the attenuation element such as a PIN diode through a driver amplifier 4. When it is defined that the external command is n bits (n is 811 integer >=2) and the sorts of digital control data to be set up in respective switches are m (m is an integer >=2, and 2<m>>n), distortion compensation for compensating the non-linear characteristic of the attenuation element can be more accurately executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an attenuator driving circuit, and more particularly to an attenuator driving circuit used in a satellite-mounted or terrestrial receiver or transmitter.

[0002]

2. Description of the Related Art Generally, an attenuator is used to control the transmission output level and power consumption of a transmitter.

An attenuator using a well-known PIN diode will be described as an example of a conventional attenuator with reference to the drawings. In FIG. 6, the conventional attenuator is a PIN diode 5
A control voltage is applied to the to change the amount of attenuation. The pulses sent from the outside (for example, the ground station) are counted, and one of the outputs 1-1 to 1-n is output according to the counted value. The pulse counter 1 to be enabled and the outputs 1-1 to 1-
n control circuits 2-1 to 2-n that are provided corresponding to n and output a predetermined voltage when the corresponding output becomes effective,
A switch circuit 3 for selecting one of the outputs of the control circuits 2-1 to 2-n, which is controlled by the output 31 from the pulse counter 1, and a PIN according to the output selected by the switch circuit 3. The driver amplifier 4 for driving the diode 5 is included.

In such a configuration, the number of pulses input from the outside is counted in the pulse counter 1, the output of the control circuit corresponding to the counted value is given to the driver amplifier 4 via the switch circuit 3, and the PIN diode 5 Is driven. In other words, the pulse from the ground station is 1
n is any value, and this value is counted by the pulse counter 1 as a command, and depending on the count result, the output of any one of the control circuits 2-1 to 2-n
The IN diode 5 is driven.

Here, if the number of control circuits is 7, PI
The voltage value applied to the N diode 5 can be changed in 7 steps, and the attenuation amount can be changed in 7 steps.

FIG. 7 is a characteristic diagram showing the relationship between the attenuation and the control voltage of an attenuator using a PIN diode. A voltage of 0 [V] is output when the count value of the pulse counter 1 is the minimum value "1", and a voltage of 1 [V] is output when the count value is the maximum value "n". Therefore, if n = 7, 0 to 1
The voltage range of [V] can be changed in 7 steps. That is, in order to correct the nonlinearity of the characteristic curve, 0
The control voltage range of 1 [V] can be set in 7 steps according to the count value of the pulse counter 1.

As shown in this characteristic diagram, there is nonlinearity near the maximum and minimum values of the count value and linearity at the central portion of the control voltage. That is, the pulse number i
If (i = 1 to n) is the value of the central part of the control voltage, the differential value (slope) of this characteristic curve is almost constant, but the differential value is not constant near the minimum value and the maximum value.

Therefore, in order to make the characteristics linear for all values of the count value, distortion compensation is performed so that the control voltage near the maximum value and the minimum value of the count value is corrected and the characteristics become linear. There is a need. At high temperature, H (Ho
t), A (Ambient) at room temperature and C (Co
Id) has a temperature characteristic that changes as illustrated. Therefore, it is necessary to perform temperature compensation.

For this reason, in the conventional drive circuit, a voltage generation circuit for generating a preset voltage and a temperature compensation circuit for temperature compensation are provided in each of the control circuits 2-1 to 2-n. is there.

The internal structure of the control circuits 2-1 to 2-n will be described with reference to the drawings. FIG. 8 shows an internal configuration example of the control circuit 2-1. In the figure, the control circuit 2-1 turns on the transistor switch circuit 9 which is turned on when the output 1-1 of the pulse counter 1 is "1" and turned off when the output 1-1 is "0". A voltage generation circuit 1 which responds to generate a preset voltage
0 and a temperature compensating circuit 8 for compensating the temperature of the generated voltage.

The voltage generating circuit 10 has a variable resistor 100. By adjusting this resistor 100 in advance,
A voltage that compensates for the distortion is generated.

The temperature compensating circuit 8 includes a thermistor Z1 having a positive characteristic with respect to temperature and a thermistor Z2 having a negative characteristic with respect to temperature, and the resistance values of the resistors R1 to R4. Is optimally selected for temperature compensation of the voltage generated by the voltage generating circuit 10.

As described above, the conventional drive circuit for the attenuation element is provided with n control circuits for performing temperature compensation and distortion compensation. By selecting these control circuits with the switch circuit, the temperature and The linearity is compensated.

[0014]

SUMMARY OF THE INVENTION The above-mentioned conventional drive circuit for an attenuating element is designed to change the attenuation amount by n steps.
It is necessary to provide n control circuits for performing temperature compensation and distortion compensation, and there is a drawback that the weight and size of the circuit become large when it is desired to increase the number of steps. In particular, it is not an appropriate structure for a satellite-mounted circuit that needs to be lightweight. Further, since the switch circuit 3 is switched for each count value, it is necessary to adjust the variable resistor for compensating the distortion for each control circuit, which makes the adjustment work troublesome and the adjustment time becomes long. was there.

Here, as a known technique for linearizing the attenuation characteristic of the PIN diode attenuator, Japanese Patent Laid-Open No. 62-53015.
However, even with this known technique, it is necessary to adjust the resistance value ratio, and there is a drawback in that the adjustment work is also troublesome.

Further, the temperature compensating circuit in the control circuit needs to be adjusted according to the output impedance of the switch circuit 3. However, since the switch circuit 3 is switched for each count value, the temperature compensating circuit is provided for each control circuit. Had to be adjusted as a unit, and the circuit became complicated.

Here, Japanese Patent Publication No. 62-50003 is known as a known technique for temperature compensation of the drive circuit of the variable attenuator, but the temperature compensation circuit must be integrally adjusted for each control circuit also by this known technique. However, there is a drawback that the circuit becomes complicated.

Further, using the conventional circuit described above, FIG.
AGC (Automatic G
When the ain control circuit is configured, there is a drawback that the amount of attenuation becomes abnormal due to a transient voltage when the switch circuit is switched. That is, the above-mentioned conventional circuit is shown in FIG.
As shown in (a), the voltage generation circuits e1 to en of the voltage generation circuit in each control circuit are equivalently switched by the switch circuit 3, and as shown in FIG. There is a drawback in that the output 40 is instantaneously interrupted for t time, the attenuation amount instantaneously becomes zero, and the output of the AGC circuit is not constant as shown in FIG. In FIG. 9, 80 is an attenuator using a PIN diode (FIG. 6),
Reference numeral 81 is an amplifier, and 82 is a gain adjuster.

The present invention has been made in order to solve the above-mentioned drawbacks of the prior art, and its object is a drive circuit for an attenuating element whose circuit configuration and its adjustment are simple and whose attenuation amount does not become abnormal. Is to provide.

[0020]

A damping element drive circuit according to the present invention attenuates an attenuation element by outputting n kinds of control voltages corresponding to an external command consisting of n bits (n is an integer of 2 or more). A drive circuit for controlling the amount of change into n types, each of which has m bits (m is an integer of 2 or more, and 2 ^m
> N) control data output means for selectively outputting n kinds of digital control data preset by the data according to the external command, and conversion for converting the output digital control data into an analog voltage. And means,
The conversion output is used as the control voltage.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a drive circuit for an attenuation element according to the present invention, and the same parts as those in FIG. 6 are designated by the same reference numerals.

In the figure, the driving circuit according to the embodiment of the present invention is different from the conventional circuit in that an m-bit generator 6 for outputting an m-bit value according to the output of the pulse counter 1 is provided, and a switch is further provided. The point is that the D / A converter 7 is used without using a circuit.

The pulse from the ground station has a value of any of 1 to n, and this value is counted by the pulse counter 1 as a command, and one of the outputs 1-1 to 1-n is output according to the counting result. Becomes effective.

The m-bit generator 6 is composed of, for example, a line decoder, a line receiver, and the like.
It is for transmitting bit digital data. Then, the output m-bit digital data is D /
It is converted into an analog voltage by the A converter 7.

Further, in the present driving circuit, since the temperature compensating circuit 8 is provided on the output side of the amplifier 4, only temperature compensation adjustment can be performed independently.

Next, a configuration example of the m-bit generator 6 will be described with reference to FIG. In FIG. 2, the same parts as those in FIG. 1 are indicated by the same reference numerals.

In the figure, the m-bit generators 6 each have 4
It is configured to include line receivers 6-1 to 6-7 which generate bit (m = 4) digital data.

Switches 61-1 to 61-7 are provided corresponding to the line receivers 6-1 to 6-7, respectively. Each of these switches 61-1 to 61-7 has 4
It has an output of bits and is preset to a value of "0" or "1" for each bit.

That is, the outputs 1-1 to 1 of the pulse counter 1
The line receivers 6-1 to 6-7 selected by -7 output 4-bit values preset by the switches 61-1 to 61-7.

In such a configuration, first, a pulse is input to the pulse counter 1 from the outside, and only one of the outputs 1-1 to 1-7 becomes effective according to the count value.
As a result, any one of the line receivers 6-1 to 6-7 becomes effective.

The outputs of the line receivers 6-1 to 6-7 are D
When input to the / A converter 7, it is converted to an analog voltage and input to the amplifier 4.

Here, the count value of the pulse counter 1 is "1".
In that case, the line receiver 6-1 becomes effective, and the value preset in the switch 61-1 is input to the D / A converter 7. If the count value of the pulse counter 1 is "7", the line receiver 6-7 is enabled and the value preset in the switch 61-7 is input to the D / A converter 7. .

Here, the output of each switch is 4 bits, can take a value of 1 to 15, and the voltage value can be set to 15 steps (15 types).

That is, in this embodiment, 7 steps (7 kinds), that is, input of 3 bits of binary number,
Since the output is converted in steps, that is, for 4 bits, distortion compensation for compensating for non-linearity can be performed more finely.

Next, the setting method of each switch is shown in FIG.
Will be described with reference to. FIG. 3 is a characteristic diagram showing the relationship between the amount of attenuation of an attenuator using a PIN diode and the control voltage, and the same portions as those in FIG. 7 are designated by the same reference numerals.

In this example, in order to correct the nonlinearity of the characteristic curve, the control voltage range of 0 to 1 [V] can be set to 15 steps according to the count value of the pulse counter 1. That is, the number of pulses to the pulse counter 1 is 7 steps (3
However, the output of the m-bit generator is converted into 15 steps (4 bits).

Assuming that the reference voltage in the D / A converter 7 is e0, conventionally (1/7) × e0 [V] per step
In this example, the voltage of
Since the voltage is converted to a voltage of / 15) × e0 [V], the setting accuracy of about 2 times can be obtained by increasing 1 bit from 3 bits to 4 bits.

Here, when the number of pulses input to the pulse counter 1 is "3", the voltage required to correct the non-linearity of the characteristic curve is (1/15) × e0 × (3 + 2).
If it is [V], the switch 61-3 may be set so that (5/15) × e0 [V] is transmitted from the line receiver 6-3 (not shown).

Therefore, 5 = 1 × 2 ⁰ + 0 × 2 ¹ +1
Since it is × 2 ² + 0 × 2 ³ , switch 61-3 is
It may be set to 1,0,1,0. Therefore, switch 6
The 1-3 least significant bit is set to on, the second bit is set to off, the third bit is set to on, and the most significant bit is set to off.

The line receivers 6-1 to 6-1 have such settings.
Do all of 6-7 beforehand.

Next, another configuration example of the m-bit generator 6 will be described with reference to FIG.

In this example, it is premised that the pulse counter 1 converts the count value into a binary number and outputs the outputs 1-1 to 1-3.

The m-bit generator 6 of this example has one of a gate circuit 60 having a function of decoding the outputs 1-1 to 1-3 of the pulse counter 1 and outputs 1 to G7 of the gate circuit 60. Only one line receiver 6-
1 to 6-7 are included.

Each of the line receivers 6-1 to 6-7 has a 4-bit output as in the case of FIG. 2, and its 4-bit input is "6" for each bit by the switches 61-1 to 61-7. It is preset to a value of "0" or "1". Therefore, the switch 61-1 is selected from the line receivers 6-1 to 6-7 selected by the outputs G1 to G7 of the gate circuit 6.
A value of 4 bits set in advance by 61 to 61-7 is output. Other configurations are the same as those in FIG.

In this structure, a pulse is input to the pulse counter 1 from the outside, and the output 1 is output according to the count value.
Values from -1 to 1-3 are determined. Then, the 3-bit outputs 1-1 to 1-3 are input to the gate circuit 60, and only one of the outputs G1 to G7 becomes valid. As a result, any one of the line receivers 6-1 to 6-7 becomes effective.

The outputs of the line receivers 6-1 to 6-7 are D
When input to the / A converter 7, it is converted to an analog voltage and input to the amplifier 4.

Here, the count value of the pulse counter 1 is "1".
In that case, the line receiver 6-1 becomes effective, and the value preset in the switch 61-1 is input to the D / A converter 7. If the count value of the pulse counter 1 is "7", the line receiver 6-7 is enabled and the value preset in the switch 61-7 is input to the D / A converter 7. . The output of each switch is 4 bits and can take a value of 1 to 15, and the voltage value can be changed in 15 steps.

That is, in the present embodiment as well, 7 steps,
That is, since the input for 3 bits is converted into the output for 15 steps, that is, the output for 4 bits, the distortion compensation for compensating the non-linearity can be performed more finely.

Furthermore, if the AGC circuit (FIG. 9) described above is constructed using the circuit of this embodiment, the amount of attenuation does not become abnormal because the switch circuit is not used. That is, in the circuit of this embodiment, since the digital data is converted into the analog voltage by using the D / A converter, the voltage to the PIN diode is not interrupted and the output of the AGC circuit is kept constant. be able to.

If necessary, a low pass filter (LPF) 11 may be provided between the D / A converter 7 and the driver amplifier 4 as shown in FIG. 5 (a). With this configuration, the output 70 of the D / A converter 7 shown in FIG. 7B becomes as shown in FIG.

As described above, in the present invention, n kinds of digital control data preset by the m-bit data according to the external command consisting of n bits are selectively output, and the output data is output. It is converted into an analog voltage. Here, both n and m are integers of 2 or more, and if 2 ^m > n, distortion compensation for compensating for non-linearity can be performed more finely.

Further, since the temperature compensation circuit is provided on the output side of the D / A converter, only the temperature compensation adjustment can be performed independently.

Although the attenuation element is a PIN diode in the above-mentioned embodiment, it is obvious that the present invention can be applied to other attenuation elements.

[0055]

As described above, according to the present invention, the distortion compensation for linearly correcting the characteristic curve is digitally performed, and the arrangement of the temperature compensation circuit is changed, so that the adjustment is easy and the circuit configuration is simple. There is an effect. Further, since the digital data is converted into an analog voltage and used as the control voltage of the attenuation element without using the switch circuit, there is an effect that the instantaneous interruption does not occur and the attenuation amount does not become abnormal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a drive circuit for an attenuation element according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of m-bit generators 6-1 to 6-n and the like in FIG.

FIG. 3 is a characteristic diagram of a drive circuit for an attenuation element.

4 is a block diagram showing another configuration example of the m-bit generators 6-1 to 6-n and the like in FIG.

FIG. 5A is a schematic diagram of the output side of the D / A converter 7,
FIGS. 7B and 7C are waveform diagrams showing the operation of each part of FIG.

FIG. 6 is a block diagram showing a configuration of a conventional drive circuit for an attenuation element.

FIG. 7 is a characteristic diagram of a conventional drive circuit for an attenuation element.

8 is a circuit showing an internal configuration example of a control circuit in FIG.

FIG. 9 is a configuration diagram when a drive circuit for an attenuation element is used in an AGC circuit.

10A is an equivalent circuit of the drive circuit of FIG. 5, and FIGS. 10B and 10C are waveform diagrams showing the operation of the AGC circuit.

[Explanation of symbols]

 1 pulse counter 2-1 to 2-n control circuit 3 switch circuit 4 driver amplifier 5 PIN diode 6-1 to 6-nm bit generator 7 D / A converter 8 temperature compensation circuit

Claims (3)

[Claims] 1. A drive circuit for controlling an attenuation amount of an attenuation element to change to n types by outputting n types of control voltages corresponding to an external command consisting of n bits (n is an integer of 2 or more), Each is m bits (m is an integer of 2 or more, and 2
Control data output means for selectively outputting n kinds of digital control data preset by the data of ^m > n) according to the external command, and converting the output digital control data into an analog voltage. A drive circuit including a conversion means, wherein the converted output is the control voltage. 2. The drive circuit according to claim 1, further comprising temperature compensating means for compensating the temperature of the converted output. 3. The drive circuit according to claim 1, wherein the attenuation element is a PIN diode.