JPH0969757A - Tuning circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To not only miniaturize the shape of the whole of a radio device but also keep the signal purity of an oscillation circuit high to provide many reception channels by generating a selection voltage corresponding to user's designation contents and applying it to a varactor diode of a frequency selection part to adjust the tuning frequency of the frequency selection part. SOLUTION: When the user designates a reception channel, designation contents are fetched by a CPU circuit 2, and selection voltage data corresponding to designation contents is outputted from a voltage information table 7. It is converted into an analog signal by a D/A conversion part 8 and is applied to a varactor diode 3 of a frequency selection part 6. Then, the varactor diode 3 has a capacity corresponding to the frequency of a signal as the selection object, and the frequency selection part 6 selects the tuning frequency corresponding to the capacity of the varactor diode 3, the capacity of a capacitor 4, and the inductance of a coil 5, and the signal of the selection object frequency in the high frequency signal obtained by the antenna of the radio device is extracted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tuning circuit that widens the reception band of various wireless devices and facilitates multi-channelization.

[0002]

2. Description of the Related Art When the reception band of a wireless device is widened to increase the number of channels, it is necessary to adjust the selection characteristics of the reception high frequency section.
It is necessary to make the single-peak characteristic of each channel steep over a wide band, and as technologies for this purpose, technologies such as a preset tuning method and a filter switching method have been developed. FIG. 6 is a circuit diagram showing an example of a tuning circuit using the preset tuning method among the preset tuning method and the filter switching method. Tuning circuit 10 shown in this figure
1 is one of a plurality of variable resistors 102 that generate a selection voltage corresponding to the frequency of each channel to be selected and one of the selection voltages output from each variable resistor 102 according to the reception channel designated by the user. Selection voltage generator 104 configured by a switch 103 for selecting
And a variable capacitance diode (varicap) 105 having a capacitance corresponding to the selection voltage output from the selection voltage generation unit 104, a capacitor 106 connected in series with the variable capacitance diode 105, and a capacitor 106 connected in parallel therewith. Frequency selection unit 10 configured by the coil 107
8 and.

When the receiving channel is selected by the user, the switch 103 operates to select one of the selection voltages output from each variable resistor 102, and this selects the variable capacitance diode 105 of the frequency selection unit 108. Is applied. As a result, this variable capacitance diode 10
5 becomes a capacitance according to the frequency of the signal to be selected, and the frequency selection unit 108 tunes according to the capacitance of the variable capacitance diode 105, the capacitance of the capacitor 106, and the inductance of the coil 107. The frequency becomes, and the signal of the selection target frequency in the high frequency signal obtained by the antenna of the wireless device is extracted.

FIG. 7 is a circuit diagram showing an example of a tuning circuit using the filter switching system among the preset tuning system and the filter switching system described above. The tuning circuit 110 shown in this figure is composed of elements such as a helical filter and a SAW filter, and has a plurality of filter elements 111 having steep characteristics that allow only signals of the frequency of each channel to be selected to pass, and each of these filters. Element 111
Among them, an input-side switch 112 that selects a filter element 111 according to a reception channel designated by a user, takes in a high-frequency signal obtained by an antenna of a wireless device, and inputs the high-frequency signal to the selected filter element 111; Of the elements 111, select the filter element 111 according to the reception channel designated by the user,
An output side switch 113 that takes in and outputs a signal of a frequency output from the filter element 111 is provided. Then, when the receiving channel is selected by the user, the input side switch 112 and the output side switch 113
Of the filter elements 111,
Filter element 111 corresponding to the designated reception channel
Is selected, and the signal of the selection target frequency in the high frequency signal obtained by the antenna of the wireless device is extracted by this filter element 111.

[0005]

The preset tuning type tuning circuit and the filter switching type tuning circuit described above have the following problems. That is, in the tuning circuit 101 using the preset tuning method shown in FIG. 6, in order to supply the selection voltage for each channel selection to the frequency selection unit 108, the variable resistors 102 for the number of channels are provided independently of other circuits. It is necessary to provide the selection voltage generation unit 104 that is arranged in the same manner or the selection voltage generation unit 104 that also serves as the control voltage circuit of the oscillation circuit (VCO) that constitutes the synthesizer unit. At this time, if the selection voltage generator 104 independent of other circuits is used,
On the circuit board, the variable resistor 102 dedicated to the reception channel selection
Since it is necessary to provide the same number as the number of receiving channels, there is a problem that the component area becomes large.
Further, when the selection voltage generator 104 that also serves as the control voltage circuit of the oscillation circuit is used, when DC noise is generated from the variable capacitance diode 105 used in the frequency selection unit 108, this DC noise is transmitted to the oscillation circuit side. There is a problem that the current flows backward and is superimposed on the control voltage of the oscillation circuit, which deteriorates the signal purity (C / N) of the oscillation circuit.
Further, in the filter switching type tuning circuit 110 shown in FIG. 7, the plurality of filter elements 111 having steep characteristics are switched to switch the tuning frequency.
If the tuning circuit 110 is made to have a wider band, the number of the filter elements 111 increases accordingly, and there is a problem that the size cannot be reduced. In view of the above circumstances, the present invention achieves multi-channel reception while reducing the number of components on the circuit board, reducing the overall shape of the wireless device, and maintaining high signal purity of the oscillator circuit. It is an object of the present invention to provide a tuning circuit capable of performing.

[0006]

In order to achieve the above object, a tuning circuit according to the present invention comprises, in claim 1, a series circuit or a parallel circuit of an inductance and a capacitance. In the tuning circuit that extracts at least one of the values and extracts the signal of the specified channel, multiple voltage data for selection necessary to select the signal of each channel is stored and specified by the user. At least one of the value of the inductance or the value of the capacitance forming the series circuit or the parallel circuit, based on the selection voltage data output from the table. Either one is made variable, and the signal of the specified channel is extracted. It is characterized by a door.

According to a second aspect, in the tuning circuit according to the first aspect, a temperature detecting element is provided on the side of the series circuit or the parallel circuit, and the temperature detecting element detects the temperature on the side of the series circuit or the parallel circuit. Then, the value of the selection voltage data output from the table is corrected according to the detection result, and the series circuit or the parallel circuit is configured based on the corrected selection voltage data obtained by this correction operation. At least one of the value of the inductance and the value of the capacitance is made variable, and the signal of the designated channel is extracted.

According to a third aspect of the present invention, in the tuning circuit according to the first or second aspect, a second inductance or a second capacitance is provided on the side of the series circuit or the parallel circuit, and the second inductance or the second capacitance is provided, depending on the range of the receiving channel. The variable range of the channel is expanded by connecting or disconnecting the second inductance or the second capacitance to the inductance or the capacitance in series or in parallel.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 is a circuit diagram showing a first embodiment of a tuning circuit according to the present invention. The tuning circuit 1a shown in this figure includes a CPU circuit 2 that controls the operation of the entire wireless device, and a variable capacitance diode (varicap) that has a capacitance according to the selection voltage output from the CPU circuit 2.
3, a variable-capacitance diode 3, a capacitor 4 connected in series, and a coil 5 connected in parallel with the capacitor 4, and a frequency selection unit 6 is provided. The C
The PU circuit 2 stores a plurality of selection voltage data necessary for selecting each channel to be selected, and outputs a voltage information table 7 for outputting selection voltage data designated by the user, and this voltage information table. And a D / A converter 8 for D / A converting (digital / analog converting) the selection voltage data output from the output terminal 7. With the above configuration, when the receiving channel is designated by the user, the CPU circuit 2 takes in the designation content of the user, and the voltage information table 7 outputs the selection voltage data corresponding to the designation content (address data). At the same time, the D / A conversion unit 8 converts the selection voltage data into an analog signal (selection voltage), which is applied to the variable capacitance diode 3 of the frequency selection unit 6.

As a result, the capacitance of the variable capacitance diode 3 becomes a capacitance according to the frequency of the signal to be selected, and the frequency selecting section 6 causes the capacitance of the variable capacitance diode 3 and the capacitance of the capacitor 4 to A tuning frequency corresponding to the inductance of the coil 5 is obtained, and a signal of a selection target frequency in the high frequency signal obtained by the antenna of the wireless device is extracted. As described above, in the first embodiment, the voltage information table 7 provided in the CPU circuit 2 is provided.
And the D / A converter 8 generate a selection voltage according to the contents specified by the user, and apply this to the variable capacitance diode 3 of the frequency selection unit 6 to change the tuning frequency of the frequency selection unit 6. Since the adjustment is made, it is possible to reduce the number of components on the circuit board, reduce the overall shape of the wireless device, and maintain the signal purity of the oscillation circuit at a high level to achieve a multi-channel reception channel. it can.

FIG. 2 is a circuit diagram showing a second embodiment of the tuning circuit according to the present invention. The tuning circuit 1b shown in this figure includes a CPU circuit 10 for controlling the operation of the entire wireless device and a C circuit.
It is configured by a variable capacitance diode (varicap) 11 having a capacitance according to the selection voltage generated by the PU circuit 10, a capacitor 12 connected in series with the variable capacitance diode 11, and a coil 13 connected in parallel with these. And a C thermistor having a resistance value according to the ambient temperature.
A temperature detection element 15 that receives the selection voltage having a constant current value output from the PU circuit 10 and transmits the selection voltage to the variable capacitance diode 11 of the frequency selection unit 14, and a voltage generated across the temperature detection element 15. In response to this, a calculation unit 21 for generating a temperature detection signal is provided.

The CPU circuit 10 stores a plurality of selection voltage data required to select each channel to be selected, and outputs a selection voltage data designated by the user, and a voltage information table 16 is provided. The calculation unit 21
A / D conversion (analog /
A / D conversion unit 17 that performs digital conversion to generate temperature detection data, and voltage correction data corresponding to each temperature detection data are stored, and the value of the temperature detection data output from the A / D conversion unit 17 is stored in the A / D conversion unit 17. The correction information table 18 that outputs the corresponding voltage correction data, and the selection voltage data that is output from the voltage information table 16 is corrected based on the voltage correction data that is output from the correction information table 18, and the temperature correction is performed. Calculation unit 19 for calculating selection voltage data
And D / A conversion (digital / analog conversion) of the temperature-corrected selection voltage data output from the calculation unit 19
And a D / A converter 20 for generating a selection voltage.

In this case, each voltage correction data stored in the correction information table 18 has a data structure centering on a reference temperature (for example, 25 ° C.) of the frequency selecting section 14 as shown in FIG. As a result, the accuracy of temperature decomposition within a predetermined temperature range centered on the reference temperature is improved, and errors due to variations in room temperature values of the thermistors forming the temperature detection element 15 are reduced. With the above configuration, when the receiving channel is selected by the user, the CPU circuit 10 takes in the contents designated by the user, and the voltage information table 16 outputs the selection voltage data corresponding to the contents designated (address data). It

In parallel with this operation, the temperature detecting element 15 detects the temperature of the frequency selecting section 14, the arithmetic section 21 outputs a temperature detection signal, and the CPU
The temperature detection signal is taken in by the circuit 10 and the A / D
The conversion unit 17 converts the temperature detection data, and the correction information table 18 outputs voltage correction data corresponding to the temperature detection data (address data). And CPU
The correction information table 1 is calculated by the calculation unit 19 of the circuit 10.
The value of the selection voltage data output from the voltage information table 16 is corrected on the basis of the voltage correction data output from 8 to obtain the temperature-corrected selection voltage data, and the D / A conversion unit 20 then The temperature-corrected selection voltage data is converted into an analog signal (selection voltage), which is the variable capacitance diode 11 of the frequency selection unit 14.
Is applied to

As a result, the variable capacitance diode 11
Becomes a capacitance according to the frequency of the signal to be selected, and the frequency selection unit 14 causes the variable capacitance diode 11 to operate.
Capacity, the capacity of the capacitor 12, and the coil 1
The frequency becomes a tuning frequency according to the inductance of No. 3, and the signal of the selection target frequency in the high frequency signal obtained by the antenna of the wireless device is extracted. As described above, in the second embodiment, the voltage information table 16 provided in the CPU circuit 10 and the D / A conversion unit 20 generate the selection voltage according to the contents specified by the user, and generate it. Since the tuning frequency of the frequency selection unit 14 is adjusted by applying the variable capacitance diode 11 of the frequency selection unit 14, the number of components on the circuit board can be reduced and the overall shape of the wireless device can be reduced. In addition, it is possible to achieve multi-channel reception while maintaining high signal purity of the oscillation circuit.

Further, in the second embodiment, the temperature detecting element 15 detects the temperature on the frequency selecting section 14 side, and the calculating section 21 generates a temperature detecting signal having a value corresponding to the detection result of the temperature detecting element 15. In addition, after the temperature detection signal is converted into temperature detection data by the A / D conversion unit 17 provided in the CPU circuit 10, the voltage correction data corresponding to the value of the temperature detection data is output from the correction information table 18. The value of the voltage data for selection output from the voltage information table 16 is corrected by the calculation unit 19 based on the voltage correction data, so that even if the ambient temperature of the frequency selection unit 14 changes, The selection characteristics of the receiving channel can be kept constant.

FIG. 4 is a circuit diagram showing a third embodiment of the tuning circuit according to the present invention. In this figure, the same parts as those shown in FIG. 2 are designated by the same reference numerals. The tuning circuit 1c shown in this figure is different from the tuning circuit 1b shown in FIG. 2 in that the frequency selecting section 14 includes a second variable capacitance diode 2
3 and a changeover switch 22 are provided, and the changeover switch 22 is operated in accordance with the value of the band changing control signal output from the CPU circuit 10 to change the second variable capacitance diode 23 to the variable capacitance diode 11. This means that they can be connected or disconnected in parallel. With the above configuration, it is determined by the CPU circuit 10 in which range range the reception channel designated by the user is, and the changeover switch 22 is operated based on the determination result, so that the second variable capacitance diode 23 operates. By connecting or disconnecting the variable capacitance diode 11 in parallel, the reception channel can be varied over a wide range. As a result, in this third embodiment, in addition to the effects of the second embodiment described above, without significantly increasing the number of parts,
It is possible to dramatically increase the number of reception channels and easily achieve multichannels.

FIG. 5 is a circuit diagram showing a fourth embodiment of the tuning circuit according to the present invention. In this figure, the same parts as those shown in FIG. 2 are designated by the same reference numerals. The tuning circuit 1d shown in this figure is different from the tuning circuit 1b shown in FIG.
5 and the changeover switch 24 are provided, and the changeover switch 24 is operated in accordance with the value of the band changing control signal output from the CPU circuit 10, so that the second variable capacitance diode 25 is changed to the variable capacitance diode 11. This means that they can be connected in series or shunted (short-circuited). With the above configuration, it is determined by the CPU circuit 10 in which range range the reception channel designated by the user is, and the changeover switch 24 is operated based on the determination result so that the second variable capacitance diode 25 is activated. The receiving channel can be varied over a wide range by being connected in series or shunted to the variable capacitance diode 11. Thus, in the fourth embodiment, similarly to the third embodiment described above, in addition to the effect of the second embodiment, the number of receiving channels can be dramatically increased without significantly increasing the number of parts. The number of channels can be increased easily.

[0019]

As described above, according to the present invention, in claim 1, the number of parts on the circuit board is reduced, the overall shape of the wireless device is reduced, and the signal purity of the oscillation circuit is increased. It is possible to achieve multi-channel reception while maintaining the same. In addition to the effect of claim 1, in claim 2, even if the ambient temperature changes, the selection characteristic of the reception channel can be kept constant. In addition to the effect of claim 1, in claim 3, the number of receiving channels can be significantly increased while reducing the number of parts.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a tuning circuit according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the tuning circuit according to the present invention.

3 is a graph showing a characteristic example of voltage correction data stored in a correction information table shown in FIG.

FIG. 4 is a circuit diagram showing a third embodiment of the tuning circuit according to the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the tuning circuit according to the present invention.

FIG. 6 is a circuit diagram showing an example of a tuning circuit using a conventionally known preset tuning method.

FIG. 7 is a circuit diagram showing an example of a tuning circuit using a conventionally known filter switching method.

[Explanation of symbols]

 1a to 1d Tuning circuit 2 CPU circuit 3 Variable capacitance diode (capacitance) 4 Capacitor (capacitance) 5 Coil (inductance) 6 Frequency selection unit 7 Voltage information table (table) 8 D / A conversion unit 10 CPU circuit 11 Variable capacitance diode ( Capacitance 12 Capacitor 13 Coil (Inductance) 14 Frequency selection unit 15 Temperature detection element 16 Voltage information table (Table) 17 A / D conversion unit 18 Correction information table 19 Calculation unit 20 D / A conversion unit 21 Calculation unit 22 Changeover switch 23 Variable capacitance diode 24 Changeover switch 25 Variable capacitance diode

Claims (3)

[Claims] 1. A tuning circuit configured by a series circuit or a parallel circuit of an inductance and a capacitance, wherein at least one of the value of the inductance and the value of the capacitance is varied to extract a signal of a designated channel. , A table for storing a plurality of selection voltage data necessary for selecting a signal of each channel and outputting the selection voltage data of the channel specified by the user is provided. A tuning circuit which extracts a signal of a designated channel by varying at least one of the value of the inductance and the value of the capacitance forming the series circuit or the parallel circuit based on voltage data. . 2. The tuning circuit according to claim 1, wherein a temperature detecting element is provided on the series circuit or parallel circuit side,
This temperature detection element detects the temperature of the series circuit or the parallel circuit side, corrects the value of the selection voltage data output from the table according to the detection result, and corrects the voltage obtained by this correction operation. Based on the voltage data for selection, at least one of the value of the inductance and the value of the capacitance forming the series circuit or the parallel circuit is varied to extract a signal of a designated channel. Tuning circuit. 3. The tuning circuit according to claim 1, wherein a second inductance or a second capacitance is provided on the side of the series circuit or the parallel circuit, and the second inductance is provided according to a range of a receiving channel. Alternatively, a tuning circuit is characterized in that a second capacitance is connected to or disconnected from the inductance or capacitance in series or in parallel to expand the variable range of the channel.