JP2001257613A - Local oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend a reception frequency range of a tuner for receiving satellite broadcast. SOLUTION: The local oscillator is provided with an oscillator 1, an oscillator 2 that oscillates a frequency of a range toward higher frequencies than that of the oscillator 1, a 1/N frequency divider means 8 that applies 1/N frequency division to the oscillated frequency from the oscillator 2, a phase shift circuit 4 that receives an output signal from the 1/N frequency divider means 8 and provides an output of two signals with a phase difference, and a control terminal 6 use to receive a selection control signal that selects either of the oscillators 1, 2 and informs the phase shift circuit 4 about which of the oscillators the phase shift circuit 4 receives its input signal. Then the 1/N frequency divider means 8 is characterized in the provision of a frequency division control circuit 15 having a function of selecting '1' or '2' for the value N in response to a voltage received from a control terminal 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local oscillator used in a tuner for receiving a direct conversion satellite broadcast.

[0002]

2. Description of the Related Art As satellite broadcasting shifts from analog broadcasting to digital broadcasting, direct conversion systems are becoming the mainstream for local oscillation devices of satellite broadcast receiving tuners. The direct conversion local oscillation device of the satellite broadcast receiving tuner has a configuration as shown in FIG.
A predetermined frequency is oscillated based on the channel selection signal input to the input terminal 5 and the selection control signal input to the control terminal 6, and the oscillated signal is output to the output terminal 9 to be output to the next mixer (not shown). ).

In the local oscillator shown in FIG. 1, the input frequency range to the satellite broadcast receiving tuner is 950 MHz.
The oscillation frequency is set to 9 so that
50MHz ~ 1500MHz and 1500MHz ~ 215
The frequency band is divided into 0 MHz, and each frequency band is oscillated by a different oscillator. This is because the bandwidth of the input frequency range to the satellite broadcast receiving tuner is wide (the maximum input frequency is about 2.26 times the minimum input frequency).
This is because it is difficult to oscillate the entire range of the input frequency with one oscillator. By the way, 1900MHz which becomes 950MHz ~ 1500MHz by dividing by 1/2
At ~ 3000 MHz, the maximum frequency is about 1.
At 58 times, 1500 MHz to 2100 MHz, the maximum frequency is 1.4 times the minimum frequency, and each can be oscillated by one oscillator.

The oscillator 1 oscillates a frequency in a band of 1500 MHz to 2150 MHz based on a tuning signal input to the input terminal 5 and is the same as the frequency of the received signal.
This oscillation frequency signal is input to the phase shift circuit 4.

On the other hand, the oscillator 2 oscillates a frequency in a band of 1900 MHz to 3000 MHz, which is twice the frequency of the received signal, based on the tuning signal input to the input terminal 5. This oscillating frequency signal is frequency-divided by で in the 分 frequency dividing circuit 3 to become a frequency signal of 950 to 1500 MHz which is the same as the frequency of the received signal, and then input to the phase shift circuit 4.

The selection of the two oscillators is performed by sending a selection control voltage from the control terminal 6 to each of the oscillator 1, the oscillator 2, and the phase shift circuit 4. The oscillator 1 operates when the selection control voltage is zero. On the other hand, the oscillator 2 operates when the selection control signal is larger than zero.

The selection control voltages are 0 and V_ccBinary voltage signal
Oscillator 1 and oscillator 2
Operates as shown in FIG. That is, the selection control voltage
Is 0, the oscillator 1 operates and the oscillator 2 does not operate.
No. On the other hand, when the selection control voltage is V _ccOscillator 2
And the oscillator 1 does not operate.

[0008] In the phase shift circuit 4 receives the oscillation signal from the oscillator 1 when the selection control voltage is 0, the oscillation frequency signal from the 1/2 frequency divider 3 when the selection control voltage V _cc Works as if you typed

Therefore, 1500 MHz to 2150 MHz
When the predetermined oscillation frequency is required, the selection control voltage is set to 0, and when the oscillation frequency of 950 MHz to 1500 MHz is required, the selection control voltage is set to _Vcc to obtain the oscillation frequency required for satellite broadcast reception. Can be.

[0010]

However, there is a movement in Japan to transfer the satellites of digital BS and digital CS to the same orbit so that they can be received by a single antenna. Input frequency range from the conventional 950 MHz to 2150 MHz to 950 MHz
It is necessary to expand to z to 2600 MHz. Therefore, a local oscillation device corresponding to a frequency range which is wider than that of the related art is required.

The present invention has been made in view of the above problems, and has as its object to provide a local oscillation device which has a relatively simple configuration and supports a frequency range which is wider than the conventional one.

[0012]

In order to achieve the above object, a local oscillator according to the present invention comprises a first oscillator for oscillating a frequency in a first range and a second oscillator for oscillating on a higher frequency side than the first range. A second oscillator that oscillates a frequency within a range, frequency dividing means for dividing the oscillation frequency from the second oscillator by １ ／, and a signal supplied from one of the first oscillator and the frequency dividing means by 90%. And a selection control means for selecting a first oscillator or a second oscillator in accordance with the frequency of the received signal. Means for supplying a frequency signal supplied from the second oscillator without performing frequency division to the phase changing means, and frequency dividing control means for controlling whether or not the frequency dividing means performs frequency division. It is characterized by having There.

Further, in the local oscillator according to the present invention, a first oscillator oscillating a frequency in a first range, a second oscillator oscillating a frequency in a second range higher than the first range, 2 The frequency of the signal output from the oscillator is 1 /
Frequency dividing means for dividing by two, phase changing means for outputting a signal supplied from one of the first oscillator and the frequency dividing means as two signals having a phase difference of 90 ° from each other; Selection means for selecting a first oscillator or a second oscillator according to a frequency, and supply means for supplying a frequency supplied from the second oscillator to the phase changing means without passing through the frequency dividing means Switching means for supplying a frequency signal supplied from a second oscillator to one of the supply means and the frequency dividing means, and switching control means for controlling the switching means. I have.

[0014]

With this configuration, in addition to the frequency signal oscillated by the first oscillator and the frequency signal divided by the frequency dividing means, the original oscillation frequency signal oscillated by the second oscillator is also converted by the phase changing means. , The oscillation frequency band of the local oscillation device is expanded.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. For convenience of description, the same parts as those in FIG. 1 showing the conventional example are denoted by the same reference numerals.
FIG. 2 is a diagram illustrating a configuration of the local oscillation device according to the first embodiment of the present invention. The 1 / N frequency dividing circuit 8 is provided with a frequency dividing control circuit 15 for switching N to 1 or 2 depending on the value of the voltage supplied from the control terminal. Frequency-division control circuit 15, when the voltage supplied from the control terminal of the V _cc / 2 or less switched to N 2, the voltage supplied is switched to 1 N when greater than V _cc / 2 from the control terminal .

The frequency division control voltage of binary 0 and V _cc from the control terminal 7 to the frequency-division control circuit 15 is supplied. Therefore, the oscillator 1 and the oscillator 2 are controlled by the selection control voltage and the frequency division control voltage.
The 1 / N frequency dividing circuit 8 operates as shown in FIG. That is, when the selection control voltage is 0, the oscillator 1 operates and the oscillator 2 does not operate.
A frequency signal in the range of 0 MHz to 2150 MHz is input.

When the selection control voltage is _Vcc and the frequency division control voltage is 0, the oscillator 1 does not operate, the oscillator 2 operates, and the 1 / N frequency dividing circuit 8 sets the frequency from the oscillator 2 to 1 / 2
Since the frequency is divided, the phase shift circuit 4 applies 950 MHz to 1
A frequency signal in the range of 500 MHz is input.

When the selection control voltage is V _cc and the frequency division control voltage is V _cc , the oscillator 1 does not operate, the oscillator 2 operates, and the 1 / N frequency dividing circuit 8 outputs the frequency signal from the oscillator 2. Is output to the phase shift circuit 4 as it is as the frequency signal of the original oscillation.
A frequency signal in a range of 0 MHz is input.

Therefore, by varying the selection control voltage and the frequency division control voltage, an oscillation frequency in the range of 950 MHz to 3000 MHz can be obtained.

Next, a second embodiment will be described with reference to FIGS. FIG. 3 is a diagram illustrating a configuration of a local oscillation device according to the second embodiment. The 1 / N frequency dividing circuit 8 is provided with the frequency dividing control circuit 15 of the first embodiment. Oscillator 1, oscillator 2, 分 divider circuit 3, and phase shift circuit 4 are supplied with three-value selection / divider control voltages of 0, V _cc / 2, and V _cc from control terminal 10.

Oscillator 1, oscillator 2 and 1 / N divider circuit 8 operate as shown in FIG. 8 by the selection / divider control voltage. That is, when the selection / division control voltage is 0, the oscillator 1 operates and the oscillator 2 does not operate, so that a frequency signal in the range of 1500 MHz to 2150 MHz is input to the phase shift circuit 4.

When the selection / frequency control voltage is _Vcc / 2, the oscillator 1 does not operate, and the oscillator 2 operates. 1 /
Since the N frequency dividing circuit 8 divides the frequency from the oscillator 2 by １ ／, the phase shift circuit 4 has 950 MHz to 1500 M
A frequency signal in the range of Hz is input.

When the selection / division control voltage is _Vcc , the oscillator 1 does not operate and the oscillator 2 operates. 1 / N
Since the frequency dividing circuit 8 outputs the original oscillation frequency signal to the phase shift circuit 4 as it is, the phase shift circuit 4
A frequency signal in the range of Hz to 3000 MHz is input.

Therefore, in the present embodiment, the selection / division control voltage is set to a ternary voltage value, so that even if there is only one control terminal, the 950 MHz frequency is the same as in the first embodiment.
An oscillation frequency in the range of up to 3000 MHz can be obtained.

Next, a third embodiment will be described with reference to FIGS. FIG. 4 is a diagram illustrating a configuration of a local oscillation device according to the third embodiment. A switching circuit 11 is provided at the next stage of the oscillator 2, and the switching circuit 11
The 分 divider circuit 3 and the bypass line 13 are arranged in parallel, and the 分 divider circuit 3 and the bypass line 13 are connected to the phase shift circuit 4 respectively. When the voltage input from the control terminal is equal to or lower than _Vcc / 2, the switching circuit 11 outputs the frequency signal input from the oscillator 2 only to the 1/2 frequency dividing circuit 3, and the voltage input from the control terminal is V
When it is larger than _cc / 2, it is output only to the bypass line 13.

The control terminal 12 is supplied with a binary switching control voltage of 0 and _Vcc . Therefore, the oscillator 1, the oscillator 2, and the switching circuit 11 operate as shown in FIG. 9 by the selection control voltage and the switching control voltage. That is, the selection control voltage is 0
In this case, the oscillator 1 operates and the oscillator 2 does not operate.
A frequency signal in the range of Hz is input.

When the selection control voltage is _Vcc and the switching control voltage is 0, the oscillator 1 does not operate, the oscillator 2 operates, and the switching circuit 11 reduces the frequency signal oscillated by the oscillator 2 to 1/2. It is supplied to the frequency dividing circuit 3. 1/2 frequency dividing circuit 3
Divides the frequency from the oscillator 2 by １ ／, a frequency signal in the range of 950 MHz to 1500 MHz is input to the phase shift circuit 4.

When the selection control voltage is _Vcc and the switching control voltage is _Vcc , the oscillator 1 does not operate, the oscillator 2 operates, and the switching circuit 11 transmits the frequency signal oscillated by the oscillator 2 to the bypass line. 13. The bypass line 13 supplies the frequency from the oscillator 2 to the phase shift circuit 4 as it is.
A frequency signal in the range of Hz to 3000 MHz is input.

Therefore, in the present embodiment, a configuration using a 1/2 frequency dividing circuit similar to the conventional example without using the 1 / N frequency dividing circuit 8 as in the first and second embodiments. An oscillation frequency in the range of 950 MHz to 3000 MHz can be obtained.

Next, a fourth embodiment will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 5 is a diagram illustrating a configuration of a local oscillation device according to the fourth embodiment. A switching circuit 11 is provided at the next stage of the oscillator 2. From the switching circuit 11, a 分 frequency dividing circuit 3 and a bypass line 13 are arranged in parallel. 13
Are connected to the phase shift circuit 4 respectively. Further, the oscillator 1, the oscillator 2, the phase shift circuit 4, and the switching circuit 11 are supplied with three-value selection / switching control voltages of 0, V _cc / 2, and V _cc from the control terminal 14.

Oscillator 1, oscillator 2 and switching circuit 11 operate as shown in FIG. 10 by the selection / switching control voltage. That is, when the selection / switching control voltage is 0, the oscillator 1 operates and the oscillator 2 does not operate, so that a frequency signal in the range of 1500 MHz to 2150 MHz is input to the phase shift circuit 4.

When the selection / switching control voltage is V _cc / 2, the oscillator 1 does not operate, the oscillator 2 operates, and the switching circuit 11 reduces the frequency signal oscillated by the oscillator 2 by 1 /.
It is supplied to the divide-by-2 circuit 3. The 1/2 frequency dividing circuit 3 includes the oscillator 2
Is divided by の, so that the phase shift circuit 4
Is input with a frequency signal in the range of 950 MHz to 1500 MHz.

When the selection / switching control voltage is _Vcc , the oscillator 1 does not operate, the oscillator 2 operates, and the switching circuit 11 supplies the frequency signal oscillated by the oscillator 2 to the bypass line 13. Since the bypass line 13 outputs the frequency from the oscillator 2 to the phase shift circuit 4 as it is, 1900 MHz to 3000
A frequency signal in the range of MHz is input.

Therefore, in the present embodiment, the selection / switching control voltage is set to three values, so that even if the number of control terminals is one, the selection / switching control voltage is 950 MHz to 300 MHz as in the third embodiment.
An oscillation frequency in the range of 0 MHz can be obtained.

Next, a direct conversion tuner provided with the local oscillation device of the present invention will be described with reference to FIG. The local oscillation device 16 is any one of the first to fourth embodiments. Local oscillator 1
Numeral 6 oscillates two signals having the same frequency as the received high-frequency signal and having a phase difference of 90 ° in response to a tuning signal from a PLL (phase locked loop) 17.

On the other hand, the signal input to the high-frequency signal input terminal 18 is filtered by a tracking band-pass filter 19 whose passing frequency band is variable according to a tuning signal output from the PLL 17 so that unnecessary frequency components are filtered out. After being amplified by 20, the signal is divided into two signals. Then, the two signals are mixed with the high frequency signal output from the local oscillation device 16 in each of the mixers 21 and 22.

The mixers 21 and 22 output two signals, P and Q, each having a phase difference of 90 °. The output signal passes through low-pass filters 23 and 24 for filtering the leakage of the local oscillation signal from the local oscillator and the sampling reference signal from the digital demodulator at the next stage.
The signals are input to terminals 25 and 26 connected to the next-stage digital demodulator.

In the embodiment of the present invention, the oscillation frequency range of the oscillator 1 is 1500 MHz to 2150 MHz.
z, the oscillation frequency range of the oscillator 2 is 1900 MHz to 30
Although set to 00 MHz, a frequency range different from these frequency ranges may be set.

[0039]

According to the present invention, the frequency dividing means has means for directly supplying the frequency signal supplied from the second oscillator to the phase changing means without performing the frequency division. In addition to the frequency signal oscillated and the frequency signal divided by the frequency dividing means, an original oscillation frequency signal oscillated by the second oscillator is also input to the phase changing means. The band expands. Thereby, the frequency band that the satellite broadcast receiving tuner can receive can be expanded.

Further, since the local oscillation device is formed as an IC, a change in circuit design accompanying the implementation of the present invention is handled within the IC, and there is no need to increase the number of peripheral circuits of the IC.
As a result, the frequency band that the satellite broadcast receiving tuner can receive can be expanded without a significant increase in cost.

Further, according to the present invention, since the selection control means and the frequency division control means use the same control terminal, the circuit configuration is simplified. Thereby, cost reduction can be achieved.

According to the present invention, the supply means supplies the frequency supplied from the second oscillator to the phase changing means without passing through the frequency dividing means, and the supply means supplies the frequency signal supplied from the second oscillator to the supply means. Since there is provided switching means for supplying to either one of the frequency dividing means and the preceding frequency dividing means, it is not necessary to add a through function to the frequency dividing means, and the frequency dividing circuit conventionally used can be used as it is. it can. Thereby, the oscillation frequency band of the local oscillator can be expanded with less change in circuit design.

Further, according to the present invention, since the selection control means and the switching control means use the same control terminal,
The circuit configuration is simplified. Thereby, cost reduction can be achieved.

Further, according to the present invention, a local oscillation device having an expanded oscillation frequency band is used as a component of a direct conversion tuner, so that a direct conversion tuner capable of receiving a wide frequency band can be realized. Thereby, when the satellites of the digital BS and the digital CS are in the same orbit, it is possible to receive the satellite with one antenna.

[Brief description of the drawings]

FIG. 1 shows a conventional local oscillation device.

FIG. 2 is a diagram showing a local oscillation device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a local oscillation device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a local oscillation device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a local oscillation device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a logical configuration of a control terminal of a conventional local oscillation device.

FIG. 7 is a diagram showing a logical configuration of a control terminal of the local oscillation device according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a logical configuration of a control terminal of a local oscillation device according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating a logical configuration of a control terminal of a local oscillation device according to a third embodiment of the present invention.

FIG. 10 is a diagram showing a logical configuration of a control terminal of a local oscillation device according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a direct conversion tuner including a local oscillation device according to the present invention.

[Explanation of symbols]

1 oscillator (oscillation frequency: 950 MHz to 1500 M
Hz) 2 oscillator (oscillation frequency: 1900 MHz to 3000)
3) 1/2 frequency dividing circuit 4 phase shift circuit 5 input terminal 6 control terminal 7 control terminal 8 1 / N frequency dividing circuit 9 output terminal 10 control terminal 11 switching circuit 12 control terminal 13 bypass line 14 control terminal 15 frequency division Control circuit 16 Local oscillation device according to the present invention 17 PLL 18 High-frequency signal input terminal 19 Tracking bandpass filter 20 RF amplifier 21, 22 Mixer 23, 24 Low-pass filter 25, 26 terminal

Claims (5)

[Claims] 1. A first oscillator that oscillates a frequency in a first range, a second oscillator that oscillates a frequency in a second range higher than the first range, and an oscillation frequency of a signal output from the second oscillator Frequency dividing means for dividing into two, phase changing means for outputting a signal supplied from one of the first oscillator and the frequency dividing means as two signals having a phase difference of 90 ° from each other; And a selection control means for selecting between the first oscillator and the second oscillator in accordance with the frequency of the signal to be generated. In the local oscillation device, the frequency dividing means is supplied from the second oscillator without performing frequency division A local oscillator comprising: means for supplying a frequency signal as it is to the phase changing means; and frequency dividing control means for controlling whether or not the frequency dividing means performs frequency division. 2. The method according to claim 1, wherein said selection control means and said frequency division control means
2. The local oscillator according to claim 1, wherein the same control terminal is used and control is performed by a ternary control signal. 3. A first oscillator oscillating a first range of frequencies, a second oscillator oscillating a second range of frequencies higher than the first range, and a frequency of a signal output from the second oscillator. Frequency dividing means for dividing by 1/2, phase changing means for outputting a signal supplied from one of the first oscillator and the frequency dividing means as two signals having a phase difference of 90 ° from each other, and receiving And a selection control means for selecting between the first oscillator and the second oscillator according to the frequency of the signal. In the local oscillation device, the frequency supplied from the second oscillator is changed without passing through the frequency dividing means. Supply means for supplying the frequency signal supplied from the second oscillator to one of the supply means and the frequency dividing means; and switching control means for controlling the switching means. That Local oscillator apparatus according to symptoms. 4. The selection control means and the switching control means,
4. The local oscillator according to claim 3, wherein the same control terminal is used and control is performed by a ternary control signal. 5. A direct conversion tuner comprising the local oscillation device according to claim 1. Description: