JPH0458754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drive circuit for a YIG (Yttrium Iron Garnet) filter that supplies a required value of current to a YIG (Yttrium Iron Garnet) filter to set the frequency distribution of its frequency selection characteristics.

(Prior Art) FIG. 6 shows a receiver using a conventional YIG filter drive circuit. are sorted by YIG filter 2,
This signal is detected by a video circuit 7 via an intermediate frequency circuit 6, and a video signal is obtained from an output terminal 8. Here, the frequency selection operation of the YIG filter 2 is performed in response to a command from a drive circuit 10 composed of a voltage generation circuit 3, a voltage selection circuit 4, and a voltage-current conversion circuit 5.

The voltage generation circuit 3 generates, for example, three types of voltages V ₁ , V ₂ ,
The voltage selection circuit 4 generates the voltage V ₃ and outputs each voltage to the voltage selection circuit 4. The voltage selection circuit 4 selects three types of input voltages V ₁ ,
Select one voltage from V ₂ and V ₃ and set the voltage -
Output to current conversion circuit 5.

The voltage-current conversion circuit 5 supplies a current proportional to the input voltage to the YIG filter 2.

As a result, the frequency selection characteristics of the YIG filter 2 are determined. For example, as shown in Figure 7B, YIG
Filter 2 is a bandpass filter whose frequency distribution has a bandwidth of Δfs, but when the voltage value corresponding to the applied current value changes to voltage V ₁ , V ₂ , and V ₃ , the bandwidth Δfs changes. The center frequency is the frequency f ₁ ,
It changes to f ₂ and f ₃ .

The input high frequency signal to such a YIG filter 2 has a frequency f ₁ and a same frequency as shown in FIG. 7A.
It is assumed that the signal consists of three signals whose center frequencies are f ₂ and f ₃ and whose frequency distribution bandwidths are Δf (Δf<Δfs). Now, if the voltage selection circuit 4 selects the voltage V ₁ , the YIG filter 2 has the frequency f ₁ as its center frequency, so the signal with the center frequency f ₁ is selected as the high frequency signal (see Figure 7). Ha)).

(Problems to be Solved by the Invention) By the way, this type of YIG filter and its drive circuit are used in a wide temperature change range, and the temperature of the voltages V ₁ , V ₂ and V ₃ generated by the voltage generation circuit 3 fluctuations due to changes in the output current, drifts in the output current due to temperature changes in the voltage-current converter circuit 5, and even YIG
If the frequency selection characteristics of the filter 2 itself change due to temperature changes, the center frequency of the screening frequency will shift from f ₁ to f ₁ +fu, for example, as shown in Figure 8B, and as a result, the YIG filter 2 will output As shown in Figure 8C, the frequency distribution of the input signal differs from the frequency distribution of the input high-frequency signal (Figure 8B)), and there is a problem in that the frequency distribution lacks a portion of the bandwidth Δf. be.

The purpose of the present invention is to
An object of the present invention is to provide a drive circuit for a YIG filter that can prevent fluctuations in the frequency selection characteristics of the YIG filter.

(Means for Solving the Problems) In order to achieve the above object, a YIG filter drive circuit according to the present invention has the following configuration.

That is, the YIG filter drive circuit according to the present invention is a YIG filter drive circuit that supplies a required current to the YIG filter and sets the frequency distribution of its frequency selection characteristic. Threshold frequency that generates an upper threshold frequency signal and a lower threshold frequency signal, which are signals with frequencies close to the high cutoff frequency and the low cutoff frequency, and separated by an appropriate frequency outside the frequency distribution. a signal generator; an upper and lower limit switching circuit that receives the upper limit threshold frequency signal and the lower limit threshold frequency signal and alternately switches and outputs both; a high frequency signal that is repeated at a constant repetition frequency and has a predetermined frequency distribution; As one input,
The output of the upper and lower limit switching circuit is used as the other input,
a filter input switching circuit that alternately switches both inputs and outputs them to the YIG filter, and selects the other input at a predetermined part of time within the repetition period of the high frequency signal; a video circuit that receives the video signal and converts it into a video signal; an inverting amplifier that receives the video signal and inverts and amplifies it; and an output of the inverting amplifier and the output of the video circuit in synchronization with the switching operation of the upper/lower limit switching circuit. A polarity switching circuit that alternately switches and outputs the output; An integrating circuit that performs the required integral operation;
an integral input switching circuit that alternately switches between the output of the integrating circuit and the output of the polarity switching circuit and outputs the output to the integrating circuit in synchronization with the switching operation of the filter switching circuit; defining frequency selection characteristics of the YIG filter; a voltage generating circuit that generates a voltage of a required value to be output; an adder that receives the voltage generated by the voltage generating circuit and the output of the integrating circuit and outputs a required voltage that is the sum of both input values; and a voltage-current conversion circuit that receives the output voltage of the filter and supplies the required current to the YIG filter.

(Operation) Next, the operation of the YIG filter drive circuit having the above configuration will be explained. In addition, in the following explanation, as the applied current value increases, the frequency distribution of the YIG filter's frequency selection characteristics shifts to the higher frequency side.
It is assumed that when the applied current value decreases, it shifts to the lower frequency side. Further, it is assumed that the detection diode included in the video circuit performs positive polarity detection.

The frequency distribution of the frequency selection characteristic of the YIG filter is set by receiving the required value current. Originally, this required value current is supplied based on the required value voltage generated by the voltage generating circuit, but in the present invention, The required value voltage is corrected based on the temperature change as follows.

That is, the upper threshold frequency signal and the lower threshold frequency signal generated by the threshold frequency signal generator are alternately switched by the upper/lower limit switching circuit and applied to the other input of the filter input switching circuit. . The filter input switching circuit takes as one input a high frequency signal that is repeated at a constant repetition frequency and has a predetermined frequency distribution, takes the output of the upper and lower limit switching circuit as the other input, and alternately switches both inputs and outputs them to the YIG filter. However, at this time, the switching operation is performed so as to select the other input at a predetermined part of time within the repetition period of the high frequency signal. In other words, if the frequency distribution of the frequency selection characteristic of the YIG filter shifts to the lower frequency side due to the influence of temperature, the lower cutoff frequency will shift to lower than the frequency of the lower limit threshold frequency signal. The threshold frequency signal will fall within the frequency distribution of the YIG filter.

As a result, the output signal of the YIG filter is A in the case of only a high frequency signal (the upper/lower limit switching circuit selects the upper threshold frequency signal), and in the case of a high frequency signal and the lower limit threshold frequency signal (the upper/lower limit switching circuit selects the upper threshold frequency signal). There is a lower limit threshold frequency signal selection) B.

Such an output signal is input to the video circuit. The output of the video circuit is input directly to the polarity switching circuit and also to the polarity switching circuit via an inverting amplifier. The polarity switching circuit alternately switches and outputs the output of the inverting amplifier and the output of the video circuit in synchronization with the switching operation of the upper limit/lower limit switching circuit. That is, in this case, when the upper and lower limit switching circuit selects the upper threshold frequency signal, it selects the output signal of the inverting amplifier;
When the lower limit threshold frequency signal is selected, the output signals of the video circuit are selected and each of them is alternately output to the integral input switching circuit.

Next, the integral input switching circuit alternately switches between the output of the integrating circuit and the output of the polarity switching circuit in synchronization with the switching operation of the filter switching circuit, and outputs the output to the integrating circuit. In other words, in this case, the integral input switching circuit performs a switching operation in synchronization with the filter input circuit, and when the filter input switching circuit selects a high frequency signal, it selects the output of the integrating circuit, and the filter input switching circuit When it selects the output of the upper/lower limit switching circuit, it selects the output of the polarity switching circuit, switches each of them, and outputs them to the integrating circuit. As a result, the integrating circuit starts an integrating operation in the time interval in which the lower limit threshold frequency signal exists when the output signal of the video circuit is B,
By repeating the integral operation, an integral output of a required value (in this case, a positive value) is provided to the adder. The adder adds the integrated output to the voltage generated by the voltage generator and outputs the result to the voltage-current conversion circuit.

As a result, the voltage-current conversion circuit supplies the required current value to the YIG filter so as to correct the frequency distribution shifted to the lower frequency side to the higher frequency side.

Note that when the frequency distribution of the frequency selection characteristic of the YIG filter shifts to the higher frequency side, the integral output becomes a negative required value, so a correction operation in the opposite direction to that described above is performed.

Since the above operations are repeated, the frequency distribution of the frequency selection characteristic of the YIG filter is not affected by temperature changes and stably maintains the desired performance.

As described above, according to the present invention, when the frequency distribution of the frequency selection characteristic of the YIG filter deviates from the normal position due to fluctuations in the YIG filter and its drive circuit due to temperature changes, this can be automatically corrected. can do.

(Example) Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 shows a YIG filter drive circuit according to an embodiment of the present invention. Note that the same components as in FIG. 6 are given the same names and symbols.

The drive circuit for this YIG filter includes the YIG filter 2, voltage generation circuit 3, voltage selection circuit 4, voltage -
In addition to the current conversion circuit 5, there are also a control circuit 102, a threshold frequency signal generation circuit 103, a threshold frequency selection circuit 104, an upper/lower limit switching circuit 105, a filter input switching circuit 106, an inverting amplifier 107,
Buffer 108, buffer 109, polarity switching circuit 11
0, integral input switching circuit 111, integral circuit 112,
and an adder 113. The control circuit 102 receives a trigger signal supplied from the outside via the input terminal 101, and sends the switching signal #1 to the upper/lower limit switching circuit 105 and the polarity switching circuit 110, and passes the switching signal #2 to the upper/lower limit switching circuit 105 and the polarity switching circuit 110.
is output to the filter input switching circuit 106 and the integral input switching circuit 111, respectively. As a result, the upper/lower limit switching circuit 105, the polarity switching circuit 110, the filter input switching circuit 106, and the integral input switching circuit 11
1 are adapted to perform the switching operation in conjunction with each other (details will be described later).

The threshold frequency signal generation circuit 103 generates a plurality of pairs of threshold frequency signals f _1L and f _1M and sends them to the threshold frequency selection circuit 104. Here, the threshold frequency signal f _1L is f _1M is set at a frequency position that is slightly lower than the low cutoff frequency position of the frequency distribution of the frequency selection characteristic of the YIG filter 2 and slightly higher than the high cutoff frequency position.

In this embodiment, it is assumed that the high frequency signal consists of three types of signals whose center frequencies are f ₁ , f ₂ and f ₃ as shown in Fig. 2A, so as shown in Fig. 2B.
Frequency distribution 3 of frequency selection characteristics of YIG filter 2
1, 32, and 33 also have center frequencies f ₁ , f ₂ , and f ₃ , respectively.

Therefore, three sets _of threshold frequency signals f _{1L and} f _1M are provided _, and as _shown in FIG. _3L ,
f _3M corresponds to the frequency distribution 33, respectively. In addition,
If the bandwidth of the high frequency signal is Δf and that of the YIG filter is Δfs, then Δfs>Δf. The threshold frequency signal selection circuit 104 is a double switch that switches in conjunction with the voltage selection circuit 4.
If is set to select voltage V ₁ , then
Among the outputs of the threshold frequency signal generation circuit 103, if the signal with the same frequency f _1M as the frequency f _1L is selected and the voltage V ₂ is selected, the frequency f _2L
If it is set to select a signal with a frequency f _2M and a voltage V ₃ , a signal with a frequency f _3L and a signal with a frequency f _3M are selected and sent to the upper/lower limit switching circuit 105, respectively. The upper/lower limit switching circuit 105 is connected to the control circuit 102
This is a switch that is switched in conjunction with the polarity switching circuit 110 by the switching signal #1 supplied from the polarity switching circuit 110, and alternately switches between the upper limit and lower limit threshold frequency signals sent from the threshold frequency signal selection circuit 104. is selected and sent to the filter input switching circuit 106.

The filter input switching circuit 106 is connected to the control circuit 102
This is a switch that is switched in conjunction with the integral input switching circuit 111 by the switching signal #2 supplied from the
The high frequency signal and the upper limit or lower limit threshold frequency signal sent from the upper/lower limit switching circuit 105 are switched in a time-division manner and sent to the YIG filter 2.

Here, how the input to the YIG filter 2 changes depending on the operation of each of the circuits described above will be explained with reference to FIG.

In Fig. 3, the high-frequency signal is a signal in which a time interval containing valid information (valid interval) of a certain length of time and a time interval containing invalid information (invalid interval) alternately continue (Fig. 3). B)).

The trigger signal is input to the control circuit 102 in synchronization with the beginning position of the effective section of this high frequency signal (FIG. 3A)). In other words, control circuit 1
02 generates the switching signals #1 and #2 in response to each input of the trigger signal 101, but the switching signal #1 supplied to the upper/lower limit switching circuit 105 changes every time a trigger signal is input. This signal controls the upper/lower limit switching circuit 105 to alternately select the upper limit threshold frequency signal f _1M and the lower limit threshold frequency signal f _1L (FIG. 3D).

Therefore, the output of the upper/lower limit switching circuit 105 is as follows:
Upper and lower threshold frequency signals are output alternately. In addition, the switching signal #2 supplied to the filter input switching circuit 106 selects the high frequency signal for a period equal to the time period including valid information of the high frequency signal after the trigger signal is input, and then the next trigger signal is input. The upper and lower limit switching circuit 105
Filter input switching circuit 1 to select the output of
06 (Figure 3C).

As a result, the input signal to the YIG filter is supplied with a high frequency signal in the time interval T ₁ containing valid information of the high frequency signal, and with the upper and lower limits in the time interval T ₁ or T ₂ containing invalid information of the high frequency signal. The threshold frequency signal becomes a signal that is alternately supplied each time a trigger signal is input (FIG. 3(e)).

Further, the output video signal of the video circuit 7 becomes one input of the polarity switching circuit 110 via the buffer 108, and also undergoes polarity inversion in the inverting amplifier 107 and passes through the buffer 109 to the polarity switching circuit 110.
This is the other input.

The polarity switching circuit 110 receives the switching signal #1, alternately switches the outputs of the buffers 108 and 109, and sends the outputs to one input terminal of the integral input switching circuit 111.

The integral output of the following integral circuit 112 is input to the other input terminal of the integral input switching circuit 111. This integral input switching circuit 111 receives the switching signal #2 and alternately switches both inputs to
12.

Integrating circuit 112 receives the output of integral input switching circuit 111, integrates it, and sends it to one input terminal of adder 113. The output of the voltage selection circuit 4 is supplied to the other input terminal of the adder 113, and the added value of both input values is sent to the voltage-current conversion circuit 5.

As a result, the frequency distribution of the selection characteristic of the YIG filter 2 is determined according to the output current value of the voltage-current conversion circuit 5. The frequency distribution of the frequency selection characteristic of the YIG filter 2 is distribution 31 when the voltage selection circuit 4 selects the voltage V ₁ , distribution 32 for the voltage V ₂ ,
For voltage V ₃ , the distribution is 33, but since the output value of the adder 113 is corrected by the voltage value selected by the voltage selection circuit 4 by the output integral value of the integration circuit 112, YIG
When the frequency selection characteristic of the filter 2 deviates due to temperature change, etc., it is input to the voltage-current conversion circuit 5.
The voltage that determines the frequency selection characteristics of the YIG filter 2 is corrected.

Next, with reference to FIGS. 4 and 5, a correction operation when the frequency selection characteristic of the YIG filter 2 deviates to the lower frequency side will be described.

First, in FIG. 4, the frequency distribution of the frequency selection characteristic of the YIG filter 2 is such that a frequency distribution 31 whose center frequency is f ₁ is selected, and the center frequency of this frequency distribution 31 is from f ₁ to f ₁ −f _D (Figure 4 A).

The high frequency signal is the same as in Figure 2, with the center frequency
High frequency signals 21, 22, 2 of f _{1 ,} f ₂ and f 3
3 is input to the YIG filter 2 in the time interval T ₁ (see FIG. 3) (FIG. 4 b).

On the other hand, the upper limit threshold frequency signal f _1M and the lower limit threshold frequency signal from the upper limit/lower limit switching circuit 105
f _1L is input to the YIG filter 2 in time intervals T ₂ and T ₃ (see FIG. 3), respectively (FIG. 4 C and D).
However, since the frequency distribution 31 of the YIG filter 2 shifted to the lower frequency side, the upper and lower limit threshold frequency signals f _1L and the middle and lower limit threshold frequency signals f _1M
f _1L falls within the frequency distribution 31 of the YIG filter 2. Further, this frequency distribution 31 contains a high frequency signal 21.

As a result, from YIG filter 2, time interval T ₁
The high frequency signal 21 is output in the time interval _T3 , and the threshold frequency signal _f1L is output in the time interval T3 (FIG. 4, E, F, and G).

Next, in FIG. 5, the signal detected and output from the video circuit 7 is YIG in the time interval _T1 .
It becomes a detection signal of the high frequency signal frequency-selected by the filter 2, becomes a no-signal O _v voltage in time interval T ₂ , and becomes a lower limit threshold frequency signal (5th voltage) in time interval T ₃ . Figure b).

The detection signal of this video circuit 7 is transmitted to the buffer 108.
The output of the buffer 108 is input to the polarity switching circuit 110 (FIG. 5C).

Furthermore, the detection signal of the video circuit 7 is transmitted to the inverting amplifier 1.
At step 07, the polarity is inverted and input as a negative voltage signal to the buffer 109, and the output of the buffer 109 is input to the polarity switching circuit 110 (FIG. 5D). The polarity switching circuit 110 switches in synchronization with the upper/lower limit switching circuit 105 by switching signal #1,
When the upper/lower limit switching circuit 105 selects the upper limit frequency threshold signal f _1M , the output of the buffer 109 is selected, and when the upper/lower limit switching circuit 105 selects the lower limit frequency threshold signal f _1L , the output of the buffer 109 is selected. 10
8 is selected and outputted to the integral input switching circuit 111 (FIG. 5, E).

Integral input switching circuit 111 switches in synchronization with filter input switching circuit 106 by switching signal #2, and when filter input switching circuit 106 selects a high frequency signal, selects the output of integrating circuit 112 (time section T ₁ ), when the filter input switching circuit 106 selects the output of the upper/lower limit switching circuit 105,
Select the output of the polarity switching circuit 110 (time interval
T ₂ , T ₃ ) and output to the integrating circuit 112 (FIG. 5). Integrating circuit 112 is integral input switching circuit 111
Adder 113
(Figure 5).

Here, the detection signal related to the lower limit threshold frequency signal f _1L in the time interval T ₃ is input to the integrating circuit 112, which is accumulated and input to the adder 113 as a required positive value.

Therefore, in the adder 113, the positive voltage inputted from the integrating circuit 112 is added to the voltage _V1 supplied from the voltage selection circuit 4, and a voltage larger than _V1 is supplied to the voltage-current conversion circuit 5. Because
The current supplied to the YIG filter 2 also increases compared to when V ₁ was supplied to the voltage-current supply circuit 5,
Correct the frequency selection characteristic of YIG filter 2 to shift it to a higher frequency. This correction is performed until the cut-off frequency on the lower frequency side of the frequency selection characteristic of the YIG filter 2 becomes higher than the lower limit threshold frequency f _1L . In addition, the frequency selection characteristic shifts to the higher frequency side, and the frequency of the upper threshold frequency signal f _1M
falls within the distribution of the frequency selection characteristic of the YIG filter 2, a detected signal of the upper threshold frequency signal is output from the video circuit 7 in the time interval _T2 . This signal is inverted by an inverting amplifier 107 and
This becomes a negative voltage signal and is input to the buffer 109. The polarity switching circuit 110 selects the output of the buffer 109 during time interval _T2 and outputs it to the integral input switching circuit, so the detection signal of the upper threshold frequency signal is supplied to the integral input switching circuit 111, The output of the input switching circuit 111 is input to an integrating circuit 112, time-integrated, and input to an adder 113. Therefore, since the voltage added to the voltage V ₁ by the adder 113 becomes a negative voltage, the frequency selection characteristic of the YIG filter 2 is corrected to shift to a lower frequency. This correction is performed until the cutoff frequency on the higher frequency side of the frequency selection characteristic of the YIG filter 2 becomes lower than the upper limit threshold frequency f _1M .

As described above, deviations in the frequency selection characteristics of the YIG filter 2 due to temperature changes can be corrected. In the above embodiment, the threshold frequency selection circuit selects a plurality of pairs of threshold frequency signals generated by the threshold frequency signal generation circuit and outputs them to the upper/lower limit switching circuit. The frequency selection circuit may be omitted and the upper/lower limit switching circuit may directly select and output the frequency.

(Effects of the Invention) As described in detail above, according to the YIG filter drive circuit of the present invention, threshold frequency signals are provided on both sides of the frequency distribution of the frequency selection characteristic of the YIG filter, and the frequency distribution of the frequency selection characteristic is Even if the frequency shifts toward either the lower frequency side or the higher frequency side due to the influence of temperature, either the upper or lower threshold frequency signal will fall into the frequency distribution of the frequency selection characteristic, and this Since the drive current of the YIG filter is corrected using the integral value of the threshold frequency signal that has entered the frequency distribution, the YIG filter and its drive circuit will fluctuate due to temperature changes, which will affect the frequency selection characteristics of the YIG filter. If the frequency distribution of deviates from the normal position, this can be automatically corrected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a YIG filter drive circuit according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the relationship between the threshold frequency signal and the frequency of the frequency selection characteristic of the YIG filter according to the present invention. , Figure 3 is
Timing diagram of input signal to YIG filter, 4th
The figure is a frequency distribution diagram of the output signal of the YIG filter when the frequency selection characteristic of the YIG filter shifts to the lower frequency side, Figure 5 is the input/output timing diagram of the integrating circuit, and Figure 6 is the drive of the conventional YIG filter. The circuit block diagram, Fig. 7 is a frequency distribution diagram showing the operation of the conventional YIG filter drive circuit, and Fig. 8 is an explanatory diagram of the problems with the conventional method. FIG. 4 is a frequency distribution diagram of the output signal of the YIG filter when the frequency is shifted to the higher frequency side. 1...High frequency signal input terminal, 2...YIG filter,
3... Voltage generation circuit, 4... Voltage selection circuit, 5... Voltage-current conversion circuit, 6... Intermediate frequency circuit, 7... Video circuit, 8... Video signal output terminal, 101... Trigger signal input terminal, 102... Control circuit, 103...Threshold frequency signal generation circuit, 104...Threshold frequency signal selection circuit, 105...Upper/lower limit switching circuit, 1
06... Filter input switching circuit, 107... Inverting amplifier, 108, 109... Buffer, 110... Polarity switching circuit, 111... Integral input switching circuit, 112... Integrating circuit, 113... Adder.

Claims (1)

[Claims] 1 A drive circuit for a YIG filter that supplies a required value of current to the YIG filter and sets the frequency distribution of its frequency selection characteristic, which is close to the high cutoff frequency and the low cutoff frequency of the frequency distribution of the YIG filter, and a threshold frequency signal generator that generates an upper threshold frequency signal and a lower threshold frequency signal that are signals of frequencies separated by an appropriate frequency outside the frequency distribution; an upper and lower limit switching circuit that receives a lower limit threshold frequency signal and alternately switches between the two and outputs the same; one input is a high frequency signal that is repeated at a constant repetition frequency and has a predetermined frequency distribution, and the output of the upper and lower limit switching circuit; as the other input, and which alternately switches both inputs and outputs them to the YIG filter, and selects the other input at a predetermined part of time within the repetition period of the high frequency signal; a video circuit that receives the output of the YIG filter and converts it into a video signal; an inverting amplifier that receives the video signal and inverts and amplifies it; and an inverting amplifier that receives the output of the YIG filter and inverts and amplifies it; a polarity switching circuit that alternately switches and outputs the output and the output of the video circuit; an integrating circuit that performs a required integral operation; an output of the integrating circuit and the polarity switching circuit in synchronization with the switching operation of the filter switching circuit; an integral input switching circuit that alternately switches the output of the YIG filter and outputs it to the integrating circuit; a voltage generating circuit that generates a voltage of a required value to define the frequency selection characteristics of the YIG filter; an adder that receives the voltage and the output of the integrating circuit and outputs a required value voltage obtained by adding both input values; a voltage that receives the output voltage of the adder and supplies the required value current to the YIG filter; A YIG filter drive circuit comprising: a current conversion circuit;