JPH11266170A - Receiving machine - Google Patents

Abstract

(57) Abstract: In a receiver including a DC-DC converter and a local oscillation circuit, reception disturbance due to noise from an oscillator for a DC-DC converter is reduced. SOLUTION: A DC-DC converter for boosting a power supply voltage is driven at a local oscillation frequency of a local oscillation circuit for reception provided in a receiver, which is used as it is.
This eliminates reception disturbance due to noise from the conventional oscillator dedicated to the DC-DC converter. As the DC-DC converter, a PWM DC-DC converter or a Cockcroft-Walton circuit is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a receiver, and more particularly, to a receiver having a DC-DC converter and a local oscillation circuit.

[0002]

2. Description of the Related Art A conventional portable radio will be described as an example. FIG. 5 is a circuit block diagram of a conventional portable radio. Radio waves are input from an antenna 61, amplified by an RF amplifier 62, mixed with an oscillation signal from a local oscillation circuit 64 by a mixer 63, converted into an intermediate frequency, and converted into a signal of only a desired intermediate frequency by an intermediate frequency filter 65. The sound signal is converted into a sound signal by the detection circuit 66, and the sound is output from the speaker 68 through the low frequency amplifier 67. At this time, in the electronic tuning type receiver, the variable capacitor 69
Is controlled by the PLL circuit 70 to oscillate the oscillation frequency of the local oscillation circuit 64 at a frequency separated from the reception frequency by an intermediate frequency. However, the voltage applied to the variable capacitor 69 requires a high voltage. The PLL circuit 70 uses 6 V or more. Therefore, in a portable radio that operates with about two dry cells, a high voltage is created using the DC-DC converter 71. Reference numeral 72 denotes an oscillator for driving the DC-DC converter (DC-DC converter oscillator).

[0003]

At this time, an oscillation circuit 72 is used in the DC-DC converter to generate noise that interferes with reception. Therefore, it takes a lot of cost to take measures against unnecessary radiation such as shielding, etc., the oscillation circuit itself uses sine wave oscillation with less harmonics, and a resistor is inserted in the rectifier circuit to prevent sudden current change. However, there is a disadvantage that the conversion efficiency is very low and the battery life is shortened. Accordingly, an object of the present invention is to provide a high-efficiency receiver free from reception interference by using a local oscillation frequency already inside a receiver having a local oscillation circuit for driving oscillation of a DC-DC converter. That is.

[0004]

According to a first aspect of the present invention, there is provided a receiver including a DC-DC converter for supplying a voltage higher than a power supply voltage and a local oscillation circuit, wherein the DC-DC converter has a local oscillation frequency of the local oscillation circuit. -A receiver for driving a DC converter.

According to a second aspect of the present invention, in the receiver according to the first aspect, the DC-DC converter is a PWM DC-DC converter that controls an output voltage of the DC-DC converter to a constant value. Machine.

A third aspect of the present invention is the receiver according to the first aspect, wherein the DC-DC converter comprises a Cockcroft-Walton circuit.

According to a fourth aspect of the present invention, there is provided the receiver according to any one of the first to third aspects, further comprising a circuit for receiving two or more frequency bands, and receiving in any one of the frequency bands. The DC-DC converter is driven by the local oscillation frequency for receiving one of the two or more frequency bands.

According to a fifth aspect of the present invention, in the receiver according to any one of the first to third aspects, a circuit for receiving two or more frequency bands is provided. When receiving one frequency band, the DC-DC converter is driven by a local oscillation frequency for receiving the frequency band, and when receiving other frequency bands, the frequency of an oscillator other than the local oscillation circuit is used. A receiver characterized in that:

According to a sixth aspect of the present invention, in the receiver according to the fifth aspect, the oscillation frequency of an oscillator other than the local oscillation circuit is the lowest frequency among the local oscillation frequencies. It is.

According to a seventh aspect of the present invention, in a receiver including a PWM type DC-DC converter for supplying a voltage higher than a power supply voltage and a local oscillation circuit, a deviation between the local oscillation frequency of the local oscillation circuit and a desired frequency is provided. PLL to monitor
And a variable capacitor for determining the local oscillation frequency, wherein an output from the local oscillation circuit and the PL
By the output from the L circuit, the PWM DC-DC
A receiver controls a reception frequency by controlling a converter and applying an output voltage of the converter to the variable capacitor.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a first embodiment of a receiver according to the present invention.
Is an RF amplifier, 13 is a mixer, 14 is a local oscillation circuit,
Reference numeral 15 denotes an intermediate frequency filter, 16 denotes a detection circuit, 17 denotes a low-frequency amplifier, 18 denotes a speaker, 19 denotes a variable capacitor, 20 denotes a PLL circuit, and 21 denotes a DC-DC converter, and details are described with reference to FIG. Same as the one. The clock used for the DC-DC converter 21 uses the oscillation frequency of the local oscillation circuit 14. As shown in FIG. 1, the DC-DC converter 21 boosts the local oscillation signal with a boosting transformer, rectifies the signal with a diode, and smoothes the signal with a capacitor.

A second embodiment of the receiver according to the present invention will be described with reference to FIGS. FIG. 2 shows the PWM method D
It is a C-DC converter (PWM type switching regulator). FIG. 3 is a diagram for explaining the operation of FIG.
FIG. 4 is a waveform diagram showing a mutual relationship of signals used. In FIG. 3, D denotes a PWM reference clock input terminal 4 in FIG.
4, A, B, and C in FIG. 3 are signals at A, B, and C in FIG. 2, respectively. In FIG. 2, 3
1 is a power supply, 32 is a capacitor for stabilizing the power supply, and 33 is a step-up coil. When a transistor 34 is turned on, a current is supplied to the coil 33 to store energy. A counter electromotive force is generated, the pulse is rectified by the rectifier 36, and the boosted voltage is supplied to the load after being smoothed by the output stabilizing capacitor 37. On the other hand, for example, a signal as shown in FIG. 3 and FIG. 3D is input to the PWM reference clock input terminal 44, and a sawtooth wave as shown in FIG. Is multiplied by 1 / a (a is an arbitrary constant) by a voltage divider 41 and a reference voltage (the value is E).
The error signal shown in FIGS. 3 and B, which is obtained by comparing 42 with the differential amplifier 38, is supplied to B, and the voltage of A and B is compared by the comparator 35, thereby obtaining a duty ratio proportional to the error signal shown in FIGS. A PWM waveform is created at C. Since energy is stored in the coil 33 with this waveform, if the output voltage decreases, the error signal rises as shown in FIG. 3C, the duty ratio of the PWM pulse increases, and accordingly the energy stored in the coil increases and the transistor 34 The back electromotive voltage generated when the switch is turned off increases, and the output voltage increases. As a result, the output voltage is controlled to a times E. Here, by inputting local oscillation to the clock input terminal 44, a high-efficiency PWM DC-DC converter using only the local oscillation frequency without interference can be realized, and this is realized by the DC-DC converter of the first embodiment. , It is possible to realize a receiver with no interference and high efficiency.

A third embodiment of the present invention will be described. By using a Cockcroft-Walton circuit, a DC-
A DC converter can be configured. That is, if a Cockcroft-Walton circuit is used for the DC-DC converter in the first embodiment, a small and inexpensive receiver can be realized.

A fourth embodiment of the present invention will be described. AM
/ FM radio, local oscillation frequency is about 1MH in AM
z to 2 MHz, FM uses about 60 MHz to 120 MHz, and FM uses high frequency. Therefore, F
When the DC-DC converter is driven using the local oscillation frequency of M, the operation speed of the internal elements cannot follow, and the efficiency is reduced, so that no significant effect can be expected. So, FM
Is received, the frequency is sufficiently lower than the reception frequency, for example, AM
If the DC-DC converter is driven by using the local oscillation frequency of
Is a higher harmonic and can be removed with a simple filter. Therefore, in the case of AM, the DC-DC converter is driven using the local oscillation frequency, and even when receiving the FM, the AM local oscillation frequency is used to eliminate the need for an FM dedicated oscillation circuit. A DC-DC converter can be realized only by the local oscillation circuit.

Next, a fifth embodiment of the present invention will be described. In the fourth embodiment, when FM is received, D is obtained by using a frequency sufficiently lower than the reception frequency, for example, several hundred KHz.
Drive the C-DC converter. By doing so, the noise that affects the FM among the noises generated by the converter becomes higher-order harmonics and can be removed with a simple filter. In the case of AM, the DC-
An efficient receiver can be realized by driving the DC converter and using another oscillation frequency sufficiently lower than the reception frequency in the case of FM.

A sixth embodiment of the present invention will be described. In the fifth embodiment, when FM is received, if the oscillation is fixed to the lowest frequency with the least interference to the FM band in the local oscillation frequency band of AM, the frequency of interference is less than that of the fifth embodiment. A circuit with easy noise suppression can be realized.

Next, a seventh embodiment of the present invention will be described. FIG.
FIG. 1 shows an example of a circuit using a PWM type DC-DC converter (PWM type switching regulator).
51 is a radio receiver, in which 52 is a local oscillator circuit,
53 is a variable capacitor for determining the oscillation frequency. In this circuit, the oscillation frequency changes according to the voltage applied to the cathode side, and the reception frequency can be changed. Reference numeral 54 denotes a PLL circuit which monitors whether or not the local oscillation frequency is oscillating at a desired frequency, and outputs a deviation amount to F as an error signal if there is a deviation. Reference numeral 55 denotes a PWM DC-DC converter described in the second embodiment, which controls the energy stored in the coil by inputting an error of the PLL circuit 54 instead of inputting the output voltage, and controlling the output voltage, that is, the variable capacitor 53 to the cathode side. Controls the voltage applied to. As a result, a voltage oscillating at a desired local oscillation frequency is applied to the cathode side by the variable capacitor 53. Since the variable capacitor 53 hardly conducts current, the load of the DC-DC converter is very light,
In addition, the PWM DC-DC converter has high efficiency, and as a result, a power supply for a tuning circuit with very low current consumption can be produced.

[0018]

According to the first aspect of the present invention, the DC-DC converter is driven by using the existing local oscillation, so that there is no possibility that the DC-DC converter-dedicated oscillator generates an interfering radio wave. It becomes unnecessary to take measures against unnecessary radiation of the DC-DC converter.

Advantageous Effect Corresponding to Claim 2: In addition to the effect corresponding to claim 1, the DC-DC converter has a PW
The use of the M-system DC-DC converter results in a DC-DC converter with high conversion efficiency, which reduces power consumption.

According to a third aspect of the present invention, in addition to the effect of the first aspect, by using a Cockcroft-Walton circuit composed of only an inexpensive and small diode and a capacitor as a DC-DC converter, Size and cost can be reduced.

Effects corresponding to claim 4: Claims 1 to 3
In addition to the effect corresponding to any one of the above, in a receiver for receiving two or more frequency bands, regardless of which frequency band is received, one of the two or more frequency bands is received. Using local oscillation frequency for DC-
Driving the DC converter facilitates measures against unnecessary radiation.

Advantages Corresponding to Claim 5: Claims 1 to 3
In addition to the effects corresponding to any of the above, in the case of receiving one frequency band of the two or more frequency bands in a receiver that receives two or more frequency bands, an existing local oscillation circuit By driving the DC-DC converter using the local oscillation frequency, unnecessary radiation countermeasures are no longer necessary, and when receiving other frequency bands, elements inside the DC-DC converter other than the local oscillation circuit are used. By driving the DC-DC converter using the frequency of an oscillator that oscillates at a frequency that can be followed by the operation speed of the device, unnecessary radiation countermeasures can be easily performed without reducing the efficiency.

According to a sixth aspect of the present invention, in addition to the effect of the fifth aspect, when the other frequency band is received, a DC-DC converter is used by using the lowest frequency among the local oscillation frequencies. By driving, unnecessary interference can be easily reduced with less disturbance.

Advantageous Effect Corresponding to Claim 7: In addition to the effect corresponding to Claim 2, a DC-DC converter dedicated to electronic tuning is provided. However, since the variable capacitor hardly conducts current, the DC-DC converter is not used. The load is very light, and the PWM DC-DC converter has high efficiency and, as a result, consumes very little current.
The power consumption of not only the converter unit but also the tuning circuit can be reduced, and the power consumption of the entire receiver can be further reduced.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram illustrating a first embodiment of a receiver according to the present invention.

FIG. 2 is a circuit block diagram for explaining a second embodiment of the receiver of the present invention.

FIG. 3 is a waveform diagram showing the mutual relationship of signals used for explaining the operation of the PWM DC-DC converter of FIG. 2;

FIG. 4 is a circuit block diagram for explaining a third embodiment of the receiver of the present invention.

FIG. 5 is a circuit block diagram of a portable radio using a conventional technique.

[Explanation of symbols]

11 antenna, 12 RF amplifier, 13 mixer
14: Local oscillation circuit, 15: Intermediate frequency filter, 16
... Detection circuit, 17 ... Low frequency amplifier, 18 ... Speaker, 1
9 ... variable capacitor, 20 ... PLL circuit, 21 ...
DC-DC converter, 31 power supply, 32 power supply stabilizing capacitor, 33 step-up coil, 34
Switching transistor, 35 ... Comparator, 3
6 ... Rectifier diode, 37 ... Output stabilization capacitor, 38 ... Differential amplifier, 39 ... Integrator, 40 ... Integrator differential amplifier, 41 ... Voltage divider, 42 ... Output voltage setting reference voltage, 43 ... Integration Dexterous reference voltage, 44: PWM reference clock input terminal, 45: DC output terminal, 51: Radio receiver main unit, 52: Local oscillation circuit, 53: Variable capacitor, 54: PLL circuit, 55: PWM DC-D
C converter, 61 antenna, 62 RF amplifier, 6
3 ... mixer, 64 ... local oscillation circuit, 65 ... intermediate frequency filter, 66 ... detection circuit, 67 ... low frequency amplifier, 68
... speaker, 69 ... variable capacitor, 70 ... PL
L circuit, 71 DC-DC converter, 72 DC-D
Oscillator for C converter, A ... sawtooth waveform in A of FIG.
Error waveform at B in FIG. 2, C: PWM waveform at C in FIG. 2, D: PWM reference clock input to 44 in FIG.
... Local oscillation frequency error signal.

Claims (7)

[Claims] 1. A DC-supply for supplying a voltage higher than a power supply voltage.
In a receiver comprising a DC converter and a local oscillation circuit, the DC-D
A receiver for driving a C converter. 2. The receiver according to claim 1, wherein the DC-DC converter is a PWM DC-DC converter that controls an output voltage of the DC-DC converter to a constant value. 3. The receiver according to claim 1, wherein said DC-DC converter comprises a Cockcroft-Walton circuit. 4. The receiver according to claim 1, further comprising a circuit for receiving two or more frequency bands, wherein the reception is performed in any one of the frequency bands. The DC-DC at the local oscillation frequency for receiving one of two or more frequency bands;
A receiver for driving a converter. 5. The receiver according to claim 1, further comprising a circuit for receiving two or more frequency bands, wherein one of the two or more frequency bands is received. When receiving, the local oscillation frequency for receiving the frequency band, and when receiving other frequency bands, the frequency of the oscillator other than the local oscillation circuit, the DC-DC
A receiver for driving a converter. 6. The receiver according to claim 5, wherein an oscillation frequency of an oscillator other than the local oscillation circuit is the lowest frequency among the local oscillation frequencies. 7. A PWM for supplying a voltage higher than a power supply voltage
In a receiver including a DC-DC converter and a local oscillation circuit, a PLL circuit that monitors a deviation between a local oscillation frequency of the local oscillation circuit and a desired frequency, and a variable capacitor that determines the local oscillation frequency, The PWM type DC-DC converter is controlled by an output from the local oscillation circuit and an output from the PLL circuit, and a reception frequency is controlled by applying an output voltage of the PWM type DC-DC converter to the variable capacitor. Receiving machine.