JPH1155033A - Oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oscillated output of a desired band while avoiding the fluctuations of band width and of a carrier/noise power ratio. SOLUTION: 1st and 2nd resonators 33 and 34 having different capacitance and inductance components, are provided and corresponding to a band switching control signal CNTB, the resonator to be connected to a variable capacitor VD2 is switched so that the oscillated outputs of different bands can be easily generated. Since the resonator has the capacitance component, the capacitance variable range of the resonance circuit changes when the resonator is switched, thus the fluctuations of the band width and of the carrier/noise power ratio caused by that band width fluctuation can be prevented when frequency bands are switched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order.

BACKGROUND OF THE INVENTION Prior Art (FIG. 7) Problems to be Solved by the Invention (FIG. 8) Means for Solving the Problems Embodiments of the Invention (1) First Embodiment (1- 1) Overall configuration of mobile phone (FIGS. 1 and 2) (1-2) Configuration of variable oscillation circuit (FIG. 3) (1-3) Specific configuration of variable oscillation circuit (FIG. 4) (1-4) Operation And effects (FIG. 5) (2) Other embodiments (FIG. 6) Effects of the invention

[0003]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillating device, and is suitably applied to, for example, a portable telephone capable of switching a frequency band to be used.

[0004]

2. Description of the Related Art In recent years, portable telephones have become widespread because telephone calls while moving or outdoors are possible. This mobile phone has a predetermined area (each cell)
It is possible to make a call by performing wireless communication with a base station installed as a fixed wireless station.

[0005] Various systems have been proposed as a wireless communication system between the portable telephone and the base station.
There is a code division multiple access system called a CDMA (Code Division Multiple Access) system. This CDMA system is a system that enables multiplex communication by making a spreading code to be multiplied by a transmission signal different for each user, and is a conventional FDMA (Frequency Division Multiple Acquisition).
cess) There is an advantage that the number of lines can be increased as compared with the method and the like. For this reason, all countries are going to introduce the CDMA system in the future.

[0006] Incidentally, the communication protocol of the CDMA system is standardized and is almost common in each country. However, due to the existing wireless communication system, the frequency band allocated to the CDMA mobile phone system will be different for each country. As shown in FIG. 7, for example, in the United States, the frequency band for transmission is about 824 to 849 [MHz],
Approximately 869 to 894 [MHz] is scheduled to be allocated as a frequency band for reception, whereas in Japan the bands for transmission and reception are reversed, and approximately 887 to 925 [MHz] for transmission.
], About 832 to 870 [MHz] will be allocated for reception.

[0007]

By the way, since the communication protocol is common even if the frequency band differs in each country, if the frequency band can be easily switched, for example, the mobile phone used in Japan is used. It can be used even when the telephone is taken abroad, which would improve convenience. Also, without actually using it overseas,
If the frequency band can be easily switched, it is possible to easily switch between manufacturing a mobile phone for Japan and a mobile phone for foreign countries simply by changing the setting of the frequency band during manufacturing, thereby reducing manufacturing costs and manufacturing efficiency. It seems that improvement can be realized.

Here, the simplest method for switching the frequency band of the portable telephone is to provide a plurality of oscillating circuits having different oscillation frequency bands with respect to the portable telephone, and to control these from outside. A method is conceivable in which a desired oscillation signal can be selected from a plurality of oscillation signals generated by the oscillation circuit. By doing so, an oscillation signal in a desired frequency band can be obtained by external control, and the mobile phone can be operated in a desired frequency band. However, in this method, since a plurality of oscillation circuits are provided, it is unavoidable to increase the size of the device, and it is hard to say that this method is very suitable for a mobile phone that requires reduction in size, weight, and power consumption.

As a second method, a method in which a variable oscillation circuit capable of changing an oscillation frequency band is provided in a portable telephone can be considered. This variable oscillation circuit generates an oscillation signal in a desired frequency band by being configured so that the resonance frequency of a resonance circuit provided therein can be largely varied. Therefore, if this variable oscillation circuit is provided in a mobile phone, the circuit scale of the oscillation circuit can be reduced as compared with the case where only a plurality of oscillation circuits are provided as described above, and as a result, the device can be downsized. I can do it.

Here, as the variable oscillation circuit, a variable oscillation circuit having a configuration as shown in FIG. 8 can be considered. The variable oscillation circuit 1 basically has an oscillation circuit called a so-called LC oscillation circuit, and has a resonance signal S1 generated by the resonance circuit 2.
Is input to the feedback amplifier 3 to obtain an oscillation output S2.

The resonance circuit 2 has first and second input terminals IN
1 and IN2. The first input terminal IN1 receives an oscillation frequency control signal CNTF. The oscillation frequency of the resonance signal S1 is changed according to the voltage level of the oscillation frequency control signal CNTF. Have been made to gain. The resonance circuit 2 receives the band switching control signal CNTB at the second input terminal IN2, and can change the frequency band of the resonance signal S1 according to the voltage level of the band switching control signal CNTB. It has been done.

Here, a variable capacitance diode VD1 called a varicap diode is connected to the first input terminal IN1, and a capacitor C1 is connected to the first input terminal IN1. In this case, the capacitance CB of the variable capacitance diode VD1 changes according to the voltage level of the oscillation frequency control signal CNTF, whereby the LC resonance circuit composed of the capacitance CB of the variable capacitance diode VD1 and the capacitance CA of the capacitor C1. Is changed so that the frequency of the resonance signal S1 can be changed.

The other end of the capacitor C1 is a capacitor C
2 is connected to the input terminal of the feedback amplifier 3 so that the resonance signal S1 generated in the resonance circuit 2 can be input to the feedback amplifier 3. The other ends of the capacitor C1 are connected to cascade-connected coils L1 and L2.
Are connected, and the coils L1 and L2, the variable capacitance diode VD1 and the capacitor C1 constitute an LC resonance circuit. In this case, a pin diode D1 is connected via a capacitor C3 to a connection midpoint between the coil L1 and the coil L2, and a second input terminal IN2 and a capacitor are connected to the anode of the pin diode D1 via a resistor R1. C4 is connected.

When the voltage level of band switching control signal CNTB input to second input terminal IN2 is at level "H", pin diode D1 is turned on (so-called on state), and the voltage of band switching control signal CNTB is turned on. When the level is "L", the connection state of the coil L2 is switched to a short-circuit state or a non-short-circuit state in accordance with the voltage level of the band switching control signal CNTB. It has been made to be. Therefore, in the resonance circuit 2, the band switching control signal CN
The inductance of the LC resonance circuit can be controlled by switching the connection state of the coil L2 according to TB, and thus the frequency band of the resonance signal S1 can be largely changed.

Here, assuming that the inductances of the coils L1 and L2 are LA and LB, respectively, the frequency f1 of the resonance signal S1 when the coil L2 is connected is expressed by the following equation.

[0016]

(Equation 1)

As shown in FIG. 2, the inductance is represented by the inductances LA and LB of the coils L1 and L2 and the capacitance C0. At this time, the capacitance C0 is obtained by changing the capacitance CB of the variable capacitance diode VD1 by the following equation.

[0018]

(Equation 2)

When the coil L2 is connected, the frequency f1 of the resonance signal S1 becomes
Next formula

[0020]

(Equation 3)

It can be varied within the range shown in FIG. Thus, as the variable oscillation circuit 1, when the coil L2 is connected, the oscillation output S2 in the frequency range represented by the equation (3) is obtained.
Can be output.

On the other hand, the frequency f2 of the resonance signal S1 when the coil L2 is short-circuited is expressed by the following equation.

[0023]

(Equation 4)

[0024] As shown in Fig. 2, the inductance L is represented by the inductance LA of the coil L1 and the capacitance C0. Also in this case, since the capacitance C0 can be changed within the range shown in the equation (2), when the coil L2 is short-circuited, the frequency f2 of the resonance signal S1 is calculated by the following equation.

[0025]

(Equation 5)

It can be changed within the range shown in FIG. Thus, as the variable oscillation circuit 1, when the coil L2 is short-circuited, the oscillation output S2 of the frequency range represented by the equation (5) is obtained.
Can be output.

By the way, in the variable oscillation circuit 1,
By controlling the connection state of the coil L2 by the band switching control signal CNTB, the oscillation output S2 of two types of bands is provided.
Can be obtained, but by changing the band only by changing the inductance of the LC resonance circuit without changing the capacitance C0 of the LC resonance circuit,
There are inconveniences when each bandwidth is different. Further, since the respective bandwidths are different from each other, an inconvenience occurs when the carrier-to-noise power ratio C / N of the oscillation output S2 fluctuates when the bandwidth is changed.

The present invention has been made in view of the above points, and proposes an oscillation device capable of obtaining an oscillation output in a desired band while avoiding a fluctuation in a bandwidth and a fluctuation in a carrier-to-noise power ratio. What you want to do.

[0029]

According to the present invention, there is provided an oscillating device for generating oscillating outputs in different frequency bands, comprising: a first resonator having a capacitance component and an inductance component; A second resonator having a capacitance component and an inductance component different from those of the first resonator, a variable capacitor whose capacitance component changes in response to an input frequency control signal, and a variable capacitor in response to an input band switching control signal. A switching switch for connecting one of the first and second resonators to a variable capacitor, and a resonance generated by a resonance circuit formed by the first or second resonator and the variable capacitor. A feedback amplifier that outputs an oscillation output by feedback-amplifying a signal is provided.

As described above, the first and second resonators having different capacitance components and inductance components are provided, and the resonator connected to the variable capacitor is switched according to the band switching control signal. Oscillation outputs of different frequency bands can be easily generated. Further, when the resonator is switched, the capacitance variable range of the resonance circuit changes because the resonator has a capacitance component. Therefore, if the capacitance component and the inductance component of the resonator are set to predetermined values in advance, the bandwidth changes when the frequency band is switched, and the carrier-to-noise power ratio generated due to the bandwidth change. Fluctuations can be avoided beforehand.

Further, according to the present invention, in an oscillating device adapted to generate oscillation outputs of different frequency bands, a first resonance signal of a desired frequency within the first frequency band is controlled in accordance with an input frequency control signal. , A first feedback amplifier that feedback-amplifies the first resonance signal to output an oscillation output within a first frequency band, and a second frequency amplifier according to the frequency control signal. A second resonance circuit that generates a second resonance signal having a desired frequency in the band, a second feedback amplifier that outputs an oscillation output in the second frequency band by feedback-amplifying the second resonance signal, and ,
A switching switch for supplying a power supply voltage to one of the first and second feedback amplifiers according to the input band switching control signal is provided.

As described above, the first frequency band is used for the first frequency band.
And a first feedback amplifier, and a second resonance circuit and a second feedback amplifier are provided for the second frequency band, and the first or second feedback amplifier is switched according to the band switching control signal. By supplying the power supply voltage to one of them, an oscillation output in a different frequency band can be easily generated. Also, in this case, since the resonance circuit and the feedback amplifier are separated for each band, if the capacitance component and the inductance component of the resonance circuit are set to predetermined values in advance, the bandwidth fluctuates when the frequency band is switched. And the fluctuation of the carrier-to-noise power ratio caused by the fluctuation of the bandwidth can be avoided.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment (1-1) Overall Configuration of Mobile Phone In FIG. 1, reference numeral 10 denotes a CD to which the present invention is applied as a whole.
1 shows a MA type mobile phone, in which an audio signal S10 collected by a microphone 11 is input to an audio processing unit 12,
Here, a predetermined encoding process is performed on the audio signal S10 to generate transmission data S11, which is input to the baseband processing unit 13. The baseband processing unit 13 uses the local signal S12 having the frequency fl3 supplied from the oscillator 14 to transmit the transmission data S11
Is subjected to a predetermined modulation process, and the resulting transmission signal S
13 is output to the transmission unit 15.

The transmitting section 15 is provided with a local signal S supplied from a variable oscillation circuit 16 constituting a channel synthesizer.
14 to perform a frequency conversion process on the transmission signal S13 to generate a transmission signal S15 of a desired channel within a transmission band defined by a communication protocol, and supply the transmission signal S15 to the antenna 18 via the antenna sharing device 17. I do. As a result, in the mobile phone 10, a transmission signal S15 corresponding to the audio signal S10 is transmitted to a base station (not shown) via the antenna 18.

On the other hand, the transmission signal transmitted from the base station is received by antenna 18. The antenna 18 receives the received signal S16 via the antenna duplexer 17 and
Output to The reception unit 19 performs a frequency conversion process using the local signal S14 supplied from the variable oscillation circuit 16 on the reception signal S16 within the reception band specified by the communication protocol, thereby obtaining the intermediate frequency reception signal. S17 is generated and output to the baseband processing unit 13.

The baseband processing section 13 has a local signal S18 having a frequency fl2 supplied from the oscillator 20.
And performs a predetermined demodulation process on the received signal S17 using
The reception data S19 obtained as a result is output to the audio processing unit 12. The audio processing unit 12 restores the audio signal S20 by performing a predetermined decoding process on the received data S19, and outputs this to the speaker 21. As a result, the mobile phone 10 can output the voice signal S20 of the communication partner transmitted via the base station from the speaker 21.

Here, the mobile phone 10 is provided with an operation unit 22 including a jog dial, various operation keys, a liquid crystal display, and the like. An operation command input through the jog dial or operation keys of the operation unit 22 is provided. The control unit 23 outputs a control command S21 to each circuit block based on the control command. Thus, in the portable telephone 10, the operation of each circuit block is controlled to perform, for example, a calling process.
The control unit 23 receives an RSSI (Received Signal Strength Indicator) signal indicating the received electric field strength from the reception unit 19 and displays the electric field strength grasped by the RSSI signal on the liquid crystal display of the operation unit 22. Has been made.

The control unit 23 also has a predetermined control data S2
2 to the baseband processing unit 13 to transmit the control data S22 to the base station via the baseband processing unit 13 and the transmitting unit 15 and the like, thereby performing various processes such as location registration and line connection. The communication is performed with a base station. The control unit 23 receives control data S23 from the base station received from the base station via the reception unit 19 and the baseband processing unit 13 from the baseband processing unit 13,
Thereby, an incoming call from the base station or the like is detected.

Further, the control section 23 outputs an oscillation frequency control signal CNTF to the variable oscillation circuit 16 to control the frequency of the local signal S14 generated by the variable oscillation circuit 16. Thus, the portable telephone 10 can perform transmission and reception on a desired channel within a band defined by a communication protocol. Further, the control unit 23 outputs a band switching control signal CNTB to the variable oscillation circuit 16 so that the frequency band of the local signal S14 generated by the variable oscillation circuit 16 can be switched to the band fl1 or fl1 '. It has been done. Thus, the mobile phone 10 can be used in, for example, both Japan and the United States where the CDMA communication protocol is the same, by switching the frequency band to be used. When the band is changed, the frequency of the local signal S12 for transmission also needs to be changed. Therefore, in this case, the control unit 23 outputs the control signal S24 to the oscillator 14 and outputs the local signal S1.
The second frequency fl3 is also changed.

Here, the frequency relationship in the mobile phone 10 will be described. First, as shown in FIG.
A band of 887 to 925 [MHz] will be allocated as a transmission band of the MA system, and a band of 832 to 870 [MHz] will be allocated as a reception band. On the other hand, in the United States, the transmission band of the CDMA system is 824.04 to 848.97 [MHz].
869.04 ~ 893.97 as the reception band
[MHz] will be assigned. Therefore, in order to be able to use in both countries, it must be possible to support these bands.

Therefore, in the portable telephone 10, the intermediate frequency of the receiving section 19 is set to 109.8 [MHz], and the oscillation frequency fl2 of the receiving oscillator 20 is set to 109.
It is set to 8 [MHz]. The variable oscillation circuit 16 has an oscillation band f of at least 722.2 to 760.2 [MHz] in accordance with the intermediate frequency 109.8 [MHz].
11, a local signal S14 of 832 to 870 [MH
z] can be received. Also, the oscillation band fl1 of the variable oscillation circuit 16 is 722.2-
In accordance with 760.2 [MHz], the oscillation frequency fl3 of the transmitting oscillator 14 is set to 164.8 [MHz].
The transmission signal S15 of up to 925 [MHz] can be transmitted. As described above, the oscillation frequency fl1 of the variable oscillation circuit 16, the reception oscillator 20, and the transmission oscillator 14,
fl2 and fl3 are respectively 722.2 to 760.2 [MHz],
By setting to 109.8 [MHz] and 164.8 [MHz], the mobile phone 10 can operate in the transmission and reception bands in Japan.

In this portable telephone 10, the oscillation frequency fl2 of the receiving oscillator 20 is maintained at 109.8 [MHz], and the band of the variable oscillation circuit 16 is set to at least 978.84
It can be changed to the oscillation band fl1 'of 1003.8 [MHz], whereby the reception band of the United States is 869.04.
The receiving signal S16 of 89893.97 [MHz] can be received. In addition, in the portable telephone 10, the oscillation frequency fl3 of the transmission oscillator 14 can be changed to 154.8 [MHz] in addition to the change of the band of the variable oscillation circuit 16, which is the transmission band in the United States. 824.04-
The transmission signal S15 of 848.97 [MHz] can be transmitted. Thus, in this portable telephone 10, the band of the variable oscillation circuit 16 can be changed to the oscillation band fl1 'of 978.84 to 1003.8 [MHz], and the oscillation frequency fl3 of the oscillator 14 for transmission can be changed to 154.8 [MHz]. As a result, it can be used not only in Japan but also in the United States.

The oscillation band fl of the variable oscillation circuit 16
1, fl1 'is strictly 722.2 to 760.2 [MHz
, 978.84 to 1003.8 [MHz], and it is sufficient that at least these ranges are included. That is, as the variable oscillation circuit 16, for example, the local signal S14 in the range of 710 to 770 [MHz] (the bandwidth is 60 [MHz]).
960 to 1,020 [MHz] (the bandwidth is also 6
0 [MHz]) can be generated.

(1-2) Configuration of Variable Oscillation Circuit Next, in this section, the configuration of the variable oscillation circuit 16 will be described with reference to FIG. As shown in FIG. 3, the variable oscillation circuit 16 is roughly composed of a resonance circuit 30, a feedback amplifier 31, and a buffer amplifier 32, and a resonance signal S30 generated by the resonance circuit 30 is input to the feedback amplifier 31. To obtain an oscillation output S31.
2 to output the local signal S14 as described above.

First, the resonance circuit 30 has two resonators 33 and 34 which are composed of a capacitance component and an inductance component, and each component is different from each other. For example, an LC resonance circuit is formed by a variable capacitance diode VD2 comprising a varicap diode, and a resonance signal S30 is generated by the LC resonance circuit.

Further, the resonance circuit 30 has first and second input terminals IN1 and IN2, and the first input terminal IN1 receives the oscillation frequency control signal CNTF. In this case, the first input terminal I
N1 is a variable capacitance diode VD2 via a coil L10.
, So that the oscillation frequency control signal CNTF received at the first input terminal IN1 can be supplied to the variable capacitance diode VD2.

The variable capacitance diode VD2 is an element whose capacitance Cx changes according to the input voltage, and the capacitance Cx changes according to the voltage level of the oscillation frequency control signal CNTF. Therefore, the oscillation frequency control signal CNT
By controlling the voltage level of F, the capacitance Cx of the variable capacitance diode VD2 can be changed. Thus, in the resonance circuit 30, the capacitance component of the LC resonance circuit can be varied by controlling the voltage level of the oscillation frequency control signal CNTF, so that a resonance signal S30 having a desired frequency can be generated. By the way, coil L10
Is an element for preventing the resonance signal S30 generated in the LC resonance circuit from flowing to another circuit via the first input terminal IN1.

The cathode of the variable capacitance diode VD2 is connected to the input terminal of the feedback amplifier 31, and
The resonance signal S30 generated in the C resonance circuit can be input to the feedback amplifier 31. The cathode of the variable capacitance diode VD2 is also connected to the switching switch 35. The switching switch 35 selects one of the two resonators 33 or 34 according to the band switching control signal CNTB input via the second input terminal IN2, and connects this to the cathode of the variable capacitance diode VD2. It is made to connect to. Thus, in the resonance circuit 30, the connection of the resonators 33 and 34 to the variable capacitance diode VD2 is switched in accordance with the band switching control signal CNTB, thereby changing the inductance component of the LC resonance circuit and changing the oscillation frequency of the resonance signal S30. The band can be changed.

Incidentally, since the resonators 33 and 34 include the capacitance component, when the resonators 33 and 34 are switched, the variable range of the capacitance component of the LC resonance circuit is also changed. Thereby, in this resonance circuit 30,
Unlike the conventional case where only the inductance component of the LC resonance circuit is simply changed, the bandwidth of each oscillation frequency band can be equalized even when the oscillation frequency band is changed.

The resonance signal S30 generated in the resonance circuit 30 is input to the feedback amplifier 31 having an amplification degree of 1 or more and is subjected to feedback amplification, whereby the variable oscillation circuit 16 oscillates at the frequency of the resonance signal S30. An oscillation output S31 can be obtained. This oscillation output S31 is output via the buffer amplifier 32 and output as a local signal S14. In this case, since the buffer amplifier 32 is provided at the output stage of the variable oscillation circuit 16, the output terminal O
It is possible to prevent the oscillation frequency from deviating from a desired value due to the impedance fluctuation of the load connected to the UT1.

(1-3) Specific Configuration of Variable Oscillation Circuit In this section, a specific configuration of the variable oscillation circuit 16 will be described. FIG. 4 in which the same reference numerals are assigned to parts corresponding to FIG. 3 shows a specific configuration of the variable oscillation circuit 16. First, in the resonance circuit 30, as in the above-described case, the first input terminal IN1 is connected to the variable capacitance diode VD2 via the coil L10 to thereby control the first input terminal I1.
The oscillation frequency control signal CNTF input to N1 is supplied to the variable capacitance diode VD2 so that the capacitance Cx of the variable capacitance diode VD2 can be varied. Thus, the resonance circuit 30 can generate a resonance signal S30 of a desired frequency by changing the capacitance component of the LC resonance circuit including the resonator 33 or 34 and the variable capacitance diode VD2.

One end of each of the above-described resonators 33 and 34 is connected to the cathode of the variable capacitance diode VD2. The resonator 33 includes a capacitor C5 and a coil L3 connected in cascade, and has a capacitance component and an inductance component. Similarly, resonator 3
Reference numeral 4 also includes a capacitor C6 and a coil L4 connected in cascade, and has a capacitance component and an inductance component. The other ends of these resonators 33 and 34 are grounded via pin diodes D2 and D3 constituting the above-mentioned switching switch 35, respectively. Incidentally, the values of the capacitors C5 and C6 and the values of the coils L3 and L4 are respectively different predetermined values.

Here, the anode of the pin diode D2 is connected to the second input terminal IN2 via the resistor R2, whereby the band switching control signal CNTB supplied to the second input terminal IN2 is transmitted to the pin diode D2. To be supplied to the anode. Pin diode D2
Is an element that switches between a conductive state and a non-conductive state according to the voltage level of the input voltage applied to the anode. Accordingly, by switching the voltage level of band switching control signal CNTB to level "H", pin diode D2 can be switched to the conductive state, and by switching the voltage level of band switching control signal CNTB to level "L", the pin can be switched to the low state. The diode D2 can be switched to a non-conductive state. In this way, in this resonance circuit 30, the conduction / non-conduction state of pin diode D2 is controlled by controlling the voltage level of band switching control signal CNTB, and the connection state of resonator 33 to variable capacitance diode VD2 is controlled. Have been made to gain.

Similarly, the third input terminal IN2 'is connected to the anode of the pin diode D3 via the resistor R3, whereby the band switching control signal CNTB' supplied to the third input terminal IN2 '. Can be supplied to the anode of the pin diode D3. Similarly, the pin diode D3 is an element whose conduction / non-conduction state is switched according to the voltage level of the input voltage applied to the anode. Therefore, by switching the voltage level of band switching control signal CNTB 'to level "H", pin diode D
3 can be switched to the conducting state, and the pin diode D3 can be switched to the non-conducting state by switching the voltage level of the band switching control signal CNTB 'to the level "L". Thus, the resonance circuit 30
Control the voltage level of the band switching control signal CNTB 'to control the conduction / non-conduction state of the pin diode D3, thereby controlling the resonator 3 with respect to the variable capacitance diode VD2.
4 can be controlled.

Thus, with such a configuration, in the resonance circuit 30, the band switching control signals CNTB, CNT
By controlling the voltage level of B ', the resonators 33 and 34 connected to the variable capacitance diode VD2 are switched, thereby changing the inductance component of the LC resonance circuit and switching the oscillation frequency band of the resonance signal S30. it can. Incidentally, in this case, the band switching control signal CN
Since the relationship between TB and the band switching control signal CNTB 'may be in opposite phases, the band switching control signal CNTB is inverted by, for example, an inverting circuit to thereby control the band switching control signal CNTB'.
By generating B ', the band switching control signal CNTB' can be easily generated.

The resonance signal S30 generated by the resonance circuit 30 as described above is supplied to the transistor Q via the capacitor C7.
1 is input to the base. The base of the transistor Q1 is grounded via a resistor R4 and a resistor R5
Is connected to a power supply Vcc via the power supply, so that a predetermined bias voltage is supplied. The collector of the transistor Q1 is connected to the power supply Vcc,
The emitter is grounded via a resistor R6 and connected to the base via a capacitor C8, whereby the transistor Q1 constitutes a feedback amplifier 31 whose output is fed back to its input. The feedback amplifier 31 having such a configuration outputs the output voltage according to the signal input to the base, thereby generating the resonance signal S30.
An oscillation output S31 corresponding to the above is output.

Oscillation output S output from feedback amplifier 31
31 is input to the base of the emitter-grounded transistor Q2. The base of the transistor Q2 is grounded via a capacitor C9, and the collector is connected to a power supply Vcc via a resistor R7, so that the transistor Q2 constitutes a buffer amplifier 32. The buffer amplifier 32 having such a configuration outputs a collector potential corresponding to a signal input to the base, thereby outputting a local signal S1 corresponding to the oscillation output S31.
4 is output to the collector end. Thus, the local signal S14 is output to the output terminal OUT1 via the coupling capacitor C10 for cutting the DC component. Incidentally, a bypass capacitor C11 is connected to a power supply line for supplying the power supply Vcc to the transistors Q1 and Q2, so that the influence of noise components generated in the power supply Vcc can be removed.

(1-4) Operation and Effect In the above configuration, in the case of the variable oscillation circuit 16, as shown in FIG. 3, two resonators 33 and 34 having a capacitance component and an inductance component are provided.
These two resonators 33 and 34 are connected to a band switching control signal CN.
Switch according to TB. In this case, the resonators 33 and 34
Are different from each other, the band of the resonance signal S30 generated in the resonance circuit 30 can be easily switched between the two bands by switching the resonators 33 and 34 connected to the variable capacitance diode VD2. . Since the resonators 33 and 34 each have a capacitance component, the variable range of the capacitance component of the resonance circuit 30 is changed by switching the connection between the resonators 33 and 34. Therefore, if the capacitance components of the resonators 33 and 34 are set to predetermined values in advance, the bandwidths of the resonance circuits 30 can be made equal when the bands are switched. Further, in the resonance circuit 30, since the bandwidths can be equalized, it is possible to prevent the carrier-to-noise power ratio C / N from fluctuating when the bands are switched.

Here, in this regard, a comparison with the conventional variable oscillation circuit 1 will be described. In the conventional variable oscillation circuit 1,
Capacitance component C0 of resonance circuit 2 is equal to capacitor C1.
And the capacitance CB of the variable capacitance diode VD1.

[0061]

(Equation 6)

Is represented by Here, the variable capacitance diode V
Assuming that the minimum value of the capacitance CB of D1 is CBmin, the minimum value Cmin of the capacitance component C0 is expressed by the following equation.

[0063]

(Equation 7)

Is represented by Further, assuming that the maximum value of the capacitance CB is CBmax, the maximum value Cmax of the capacitance component C0 is expressed by the following equation.

[0065]

(Equation 8)

Is represented by Therefore, the capacitance component C0 of the resonance circuit 1 can be varied in the range of Cmin to Cmax shown by the equations (7) and (8).

In the conventional resonance circuit 1, as can be seen from the equations (7) and (8), even if the connection of the coil L2 is changed, the variable range of the capacitance component C0 does not change. The resonance frequencies f1 and f2 of the resonance circuit 1
Is expressed by the above-described equation (1) or (4). Therefore, if the variable range of the capacitance component C0 does not change, the connection of the coil L2 is controlled to change the inductance component to (LA +
When changing to LB) or LA, the bandwidth of the resonance frequencies f1 and f2 changes. For this reason, in the conventional variable oscillation circuit 1, when the band of the oscillation frequency is changed, there has been a problem that the bandwidth changes.

The bandwidth of the oscillation frequency is 20 [MHz] when the coil L2 is connected as shown in FIG.
If the coil L2 is short-circuited and the frequency is 30 [MHz], the frequency deviation due to the noise component superimposed on the oscillation frequency control signal CNTF is increased 30/20 times when the coil L2 is short-circuited. As a result, this deviation appears as noise power, and the carrier-to-noise power ratio C / N is more deteriorated when the coil L2 is short-circuited. Thus, the conventional variable oscillation circuit 1
Then, when the band of the oscillation frequency is changed, the bandwidth fluctuates, and the carrier-to-noise power ratio C / N also fluctuates due to the fluctuation of the bandwidth, causing inconvenience.

On the other hand, in the variable oscillation circuit 16 according to the present embodiment, the band of the oscillation frequency is changed by switching the resonators 33 and 34 each including a capacitance component and an inductance component. The variable range of the capacitance component of the resonance circuit 30 changes according to the capacitance components of the resonance circuits 33 and 34. For this reason, if the capacitance components of the resonators 33 and 34 are set to predetermined values in advance, it is possible to avoid the fluctuation of the bandwidth and the fluctuation of the carrier-to-noise power ratio C / N when the oscillation frequency band is switched. be able to.

Further, in the case of the variable oscillation circuit 16, the number of components as the oscillation circuit can be reduced as compared with the conventional method of providing a plurality of oscillation circuits, thereby reducing the space on the substrate. Thus, the size and weight of the mobile phone can be reduced. In addition, by reducing the number of parts, the cost of the mobile phone can be reduced.

According to the above configuration, the first and second resonators 33 and 34 having different capacitance components and inductance components are provided, and the variable capacitance diode VD2 is controlled in accordance with the band switching control signal CNTB. By switching the resonators 33 and 34 to be connected to each other, it is possible to easily obtain the oscillation output S31 of the desired band while avoiding the fluctuation of the bandwidth and the fluctuation of the carrier-to-noise power ratio.

(2) Other Embodiments In the above embodiment, two resonators 33 and 34 are provided for the resonance circuit 30 and the resonators 33 and
4, the oscillation frequency band of the variable oscillation circuit 16 is switched. However, the present invention is not limited to this. A resonance circuit and a feedback amplifier are separately provided for each oscillation frequency band. By controlling the operation of the feedback amplifier in response to this, an effect similar to that described above can be obtained even if an oscillation output in a desired band is obtained.

This point will be specifically described with reference to FIG. In FIG. 6, in which parts corresponding to those in FIG. 3 are assigned the same reference numerals, reference numeral 40 denotes a variable oscillation circuit as a whole, and feedback amplifiers 31 and 31 'are provided for each oscillation frequency band. First, the resonator 3 is connected to the input terminal of the first feedback amplifier 31.
3 and a first resonance circuit 30 including a variable capacitance diode VD2. In the first resonance circuit 30, the oscillation frequency control signal CNTF input to the first input terminal IN1 is supplied to the variable capacitance diode VD2 via the coil L10, and the variable capacitance diode VD2 is used by using the oscillation frequency control signal CNTF. By varying the capacitance of VD2, a resonance signal S30 of a desired frequency is generated. The resonance signal S30 is input to the first feedback amplifier 31, and the first feedback amplifier 31
As a result, the signal is output as an oscillation output S31. By outputting the oscillation output S31 to the output terminal OUT1 via the buffer amplifier 32, a local signal S14 in the first oscillation frequency band can be obtained.

On the other hand, a second resonance circuit 30 'including a resonator 34 and a variable capacitance diode VD2' is connected to the input terminal of the second feedback amplifier 31 '. Also in the second resonance circuit 30 ', the oscillation frequency control signal CNTF input to the first input terminal IN1 is supplied to the variable capacitance diode VD2' via the coil L10 ', and the oscillation frequency control signal CNTF is used. Variable capacitance diode V
By varying the capacitance of D2 ', a resonance signal S30' having a desired frequency is generated. The resonance signal S30 'is similarly input to the second feedback amplifier 31', and is amplified as a feedback signal by the second feedback amplifier 31 'to be output as an oscillation output S31'. By outputting the oscillation output S31 'to the output terminal OUT1 via the buffer amplifier 32, a local signal S14 in the second oscillation frequency band can be obtained.

Incidentally, the first and second feedback amplifiers 31,
A power input terminal 31 'is connected to a power supply Vcc via a switch SW1.
The power supply Vcc is supplied according to the connection state of W1. This switch SW1 is connected to a second input terminal IN.
The connection state is switched according to the band switching control signal CNTB input to the control signal 2. Accordingly, if the connection state of the switch SW1 is controlled using the band switching control signal CNTB, the power supply voltage is supplied to only one of the first and second feedback amplifiers 31 and 31 ', and only one of the first and second feedback amplifiers 31 and 31' is supplied. Can be operated, and only the oscillation output S31 or S31 'of one of the oscillation frequency bands can be generated.

In this way, in the variable oscillation circuit 40, the frequency band of the local signal S14 can be switched by controlling the power supply to the first and second feedback amplifiers 31 and 31 '. .
Incidentally, in this case, since the resonance circuit and the feedback amplifier are separated for each band, if the capacitance component and the inductance component of each of the resonance circuits 30 and 30 'are set to predetermined values in advance, the oscillation frequency band can be reduced. It is possible to avoid the fluctuation of the bandwidth when switching and the fluctuation of the carrier-to-noise power ratio C / N caused by the fluctuation of the bandwidth. In the case of the variable oscillation circuit 40, since the variable capacitance diodes are separately provided, if the variable range of the variable capacitance diodes is changed in advance, the resonator 3
It is not always necessary to have a capacitance component as 3, 34. In the variable oscillation circuit 40, the resonance circuit and the feedback amplifier are separately provided for each band as described above, so that, for example, the 800 [MHz] band or the 1.9 [GHz] band.
Even when the bands are extremely far apart, such as a band, the capacitance and inductance components can be set to optimal values,
There is an effect that the oscillation outputs S31 and S31 'of that band can be obtained reliably. Further, by supplying power to only one of the feedback amplifiers 31 or 31 ', power consumption can be reduced as compared with a conventional case where a plurality of oscillation circuits are simply provided.

In the above embodiment, the case where the resonance signal S30 of the desired frequency is generated by changing the capacitance component of the resonance circuit by the variable capacitance diode VD2 has been described, but the present invention is not limited to this. Other variable capacitors may be used as long as the capacitance component changes according to the input frequency control signal.

In the above embodiment, the case where the local signal S14 of the frequency bands fl1 and fl1 'as shown in FIG. 2 is generated has been described. However, the present invention is not limited to this, and other frequency bands may be generated. Local signal S14
May be generated. The point is that the local signal S14 in the frequency band specified by the predetermined communication method may be generated.

In the above embodiment, the CDM
Although the case where the present invention is applied to the A-type mobile phone has been described, the present invention is not limited to this, and may be applied to other communication-type mobile phones. In short, the present invention can be widely applied to any communication terminal device having at least two or more defined frequency bands and capable of performing communication in any of those bands.

[0080]

As described above, according to the present invention, a first capacitor having different capacitance components and inductance components is provided.
And the second resonator is provided, and the resonator connected to the variable capacitor is switched according to the band switching control signal, thereby avoiding the fluctuation of the bandwidth and the fluctuation of the carrier-to-noise power ratio. Then, an oscillation output in a desired band can be obtained.

A first resonance circuit and a first feedback amplifier are provided for the first frequency band, and a second resonance circuit and a second feedback amplifier are provided for the second frequency band. By supplying the power supply voltage to one of the first and second feedback amplifiers according to the signal, it is possible to avoid fluctuations in the bandwidth and the carrier-to-noise power ratio, and A band oscillation output can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a mobile phone to which the present invention is applied.

FIG. 2 is a table showing frequency bands of each country assigned to a CDMA mobile phone;

FIG. 3 is a block diagram showing a configuration of a variable oscillation circuit.

FIG. 4 is a circuit diagram showing a specific configuration of a variable oscillation circuit.

FIG. 5 is a schematic diagram used for comparison with a conventional variable oscillation circuit.

FIG. 6 is a block diagram showing a configuration of a variable oscillation circuit according to another embodiment.

FIG. 7 is a schematic diagram used for a brief description of frequency bands assigned in each country.

FIG. 8 is a block diagram showing a conventional variable oscillation circuit.

[Explanation of symbols]

1, 16, 40 ... variable oscillation circuit, 2, 30 ... resonance circuit, 3, 31 ... feedback amplifier, 10 ... mobile phone, 1
1 microphone, 12 voice processing unit, 13 baseband processing unit, 14, 20 oscillator, 15 transmitting unit, 17 antenna duplexer, 18 antenna, 1
9 receiving section, 21 speaker, 22 operating section, 2
3 ... Control unit, 32 ... Buffer amplifier, 33, 34 ...
... resonator.

Claims (2)

[Claims] An oscillation device configured to generate an oscillation output in a different frequency band, comprising: a first resonator having a capacitance component and an inductance component; and a capacitance component and an inductance component different from the first resonator. A variable capacitance device whose capacitance component changes in response to an input frequency control signal; and a first or second capacitor in response to an input band switching control signal.
A switching switch for connecting one of the resonators to the variable capacitor, and a resonance signal generated by a resonance circuit formed by the first or second resonator and the variable capacitor. An oscillation device comprising: a feedback amplifier that outputs the oscillation output by performing feedback amplification. 2. An oscillating device adapted to generate oscillation outputs in different frequency bands, wherein a first resonance signal having a desired frequency within a first frequency band is generated according to an input frequency control signal. A first resonance circuit and the first resonance signal by feedback amplifying the first resonance signal.
A first feedback amplifier that outputs the oscillation output in a frequency band of; a second resonance circuit that generates a second resonance signal of a desired frequency in a second frequency band in response to the frequency control signal; By feedback amplifying the second resonance signal, the second resonance signal is amplified.
A second feedback amplifier that outputs the oscillation output within the frequency band of
A switching switch for supplying a power supply voltage to one of the feedback amplifiers.