JPH0410656Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an inductor for a radio receiver, a receiver included in a wireless communication device, and the like.

Background technology Amplitude modulation (abbreviation AM) in the medium wave band (abbreviation MW)
Radio receivers that can receive broadcasts and frequency modulation (FM) broadcasts in the very high frequency band (VHF) may use external antennas that share the MW band and VHF band. In order to reduce the performance degradation caused by the load effect on the AM receiving circuit and to reduce the interference of AM reception due to excessive amplitude signals outside the band when receiving AM broadcasting, the AM receiving circuit and the antenna are In some cases, an inductor is interposed between them to prevent the VHF received wave from being shunted and input to the AM receiving circuit. Also MW
Even in radio receivers dedicated to AM reception in the band,
An inductor is sometimes used between the antenna and the AM receiving circuit in order to reduce the interference of AM receiving conditions by excessive amplitude signals other than those in the MW band.

In order to miniaturize these inductors, when a core is included and the inductor is not housed in a shield case, the inductor electromagnetically absorbs harmonics such as intermediate frequency signals during AM reception or regenerated carrier waves for synchronous detection. May be picked up associatively. These inductors may also pick up local oscillation frequency signals and their harmonics in an electromagnetic manner.
Furthermore, in a receiver using a PLL circuit, these inductors may pick up signals associated with the phase lock loop frequency synthesizer and its harmonics in an electromagnetic manner. This often interferes with AM broadcast reception in the MW band and degrades the SN ratio.
When an inductor having the above-mentioned configuration is placed in the magnetic field of such a disturbing signal, an electromotive force having a polarity that follows the winding direction of the coil is generated in the inductor. The electromotive force generated in this coil tends to cause an adverse effect of deteriorating the SN ratio, especially in the antenna circuit portion where the signal level is low. Therefore, it is necessary to select and place such an inductor in a location where the magnetic flux density of the interfering signal is low. Doing so will reduce the degree of freedom in design.

In order to solve this problem, the inductor may be housed in a shield case, but this generally reduces Q and increases stray capacitance. This reduces the level of the received signal when receiving AM broadcasts, and
When receiving FM broadcasting, the received signal tends to flow to the AM receiving circuit side through the inductor, and the received signal level may drop. Furthermore, when receiving AM broadcasting, the effect of suppressing signals in other bands from flowing into the AM receiving circuit side is reduced. Furthermore, the structure becomes larger and the so-called space factor deteriorates. Moreover, the cost also increases.

Problems to be Solved by the Invention It is an object of the present invention to provide a receiver inductor that is compact and can reliably suppress interference signals.

Means for Solving the Problems The present invention provides an inductor that is connected between an antenna and a receiving circuit and suppresses the inflow of high frequency signals outside the compatible frequency band among high frequency signals from the antenna. The inductor is an inductor for a receiver, characterized in that it consists of two coils arranged in parallel, and the coils are connected in series or parallel so that the polarity of AC electromotive force in the same AC magnetic field is opposite. .

Effect According to the present invention, since the inductor is composed of a plurality of coils connected to each other so that the poles of the AC supervoltage force in the same AC magnetic field are opposite, the inductor is Even if it is arranged, the electromotive force generated thereby is canceled out.
Therefore, interference signals can be suppressed reliably.

Embodiment FIG. 1 is a front view of an embodiment of the present invention, and FIG. 2 is a sectional view taken along the section line - in FIG. 1. A coil 2 is wound around the core 1 . core 1
A coil 4 is wound around another core 3 that is arranged parallel to and close to the core 3 . The coils 2 and 4 are connected in series by a line 5 so that the polarities of AC superpower in the same AC magnetic field are opposite to each other. This inductor has terminals 6,7.

FIG. 3 shows an inductor 1 according to another embodiment of the present invention.
FIG. A coil 12 is wound around the core 11 . A coil 14 is wound around another core 13 parallel to the core 11. Coil 12 and coil 14 are connected in parallel to terminal 1.
6 and 17. The connection polarities of the coils 12 and 14 are opposite to each other.

In order for the inductor seen from the terminals 6 and 7 of the inductor 8 shown in FIG. You can choose 2. Further, in the embodiment shown in FIG. 3, in order to set the inductance seen from the terminals 16 and 17 to a desired value, the inductance of the coils 12 and 14 wound around each core 11 and 13 must be set to the desired value. You just have to choose it so that it is doubled.

According to such a configuration, the coils 2, 4;
Since inductors 2 and 14 have opposite polarities, even if the inductors 8 and 10 are placed in the magnetic field of an interfering signal, the adverse effects of the interfering signal will be suppressed. Therefore, the inductors 8 and 10 can be installed in locations where the magnetic flux density of the interference signal is relatively high, increasing the degree of freedom in design. In addition, compared to a shielded coil of the same size or cost, the Q can be made higher and the rate of increase in stray capacitance is smaller, so there is no risk of an increase in the desired signal level or interference signal level. Moreover, the structure can be miniaturized and realized at low cost. Furthermore, core 1, 3 or 1
1 and 13 are connected in parallel, it is extremely easy to attach the inductors 8 and 10 to a substrate (not shown), and the coils 2 and 4 or 12 and 1
It is advantageous if the direction of magnetic flux and the magnetic force in the magnetic field of the interfering signal acting on the sensor 4 are approximately equal.

FIG. 4 is a block diagram of a radio receiver using the inductor 8. The AM broadcast receiving circuit 21 in the MW band and the FM broadcast receiving circuit 22 in the VHF band are selectively energized by power from a power supply 23 via a changeover switch 24. MW band and
The received signal from the antenna 25 shared with the VHF band is transmitted through the inductor 8 according to the present invention.
The signal is applied to the AM broadcast receiving circuit 21. This inductor 8 can also be used as part of the tuning circuit or impedance matching circuit of the AM broadcast receiving circuit 21.

The signal from the antenna 25 is also connected to a capacitor 26 for suppressing the AM broadcast signal from being shunted.
The signal is applied to the FM broadcast receiving circuit 22 via the FM broadcast receiving circuit 22.
The demodulated signals from the AM broadcast receiving circuit 21 and the FM broadcast receiving circuit 22 are amplified by the amplifier circuit 27 and converted into sound by the speaker 28.

A radio receiver dedicated to AM broadcasting is shown in FIG. The AM reception signal from the antenna 29 is given to the AM broadcast reception circuit 21 via the inductor 8. The demodulated signal from the AM receiving circuit 21 is amplified by the amplifier circuit 27 and converted into sound by the speaker 28.

FIG. 6 is a block diagram showing a simplified configuration example of the AM broadcast receiving circuit 21 of FIGS. 4 and 5. In FIG. In this AM broadcast receiving circuit 21, AM
After the broadcast signal passes through an inductor 8, it is sent to a high frequency amplifier circuit 3 having an impedance matching circuit on the input side.
After that, the tuning circuit 31 selects the AM broadcast to be received, the frequency conversion circuit 32 performs frequency conversion, and the intermediate frequency signal obtained by this is amplified by the intermediate frequency amplification circuit. 33
and detected by the detection circuit 34.

In the AM broadcast receiving circuit 21a having another configuration shown in FIG.
After the signal to be received is selected by the tuning circuit 35, it is amplified by the high frequency amplification circuit 36. The output from the high frequency amplification circuit 36 is guided to a tuning circuit 37, where unnecessary signals are attenuated, and then converted into an intermediate frequency signal by a frequency conversion circuit 38, and then converted into an intermediate frequency signal by an intermediate frequency amplification circuit 39. The signal is amplified and detected by the detection circuit 40.

The present invention can be implemented in connection with the AM receiving circuits 21, 21a, etc. having the configurations shown in FIGS. The same applies to the inductor 10.

Effects As described above, according to the present invention, it is possible to realize a receiver inductor that is small and can reliably suppress interference signals. This makes it easy to decide where to install the inductor, increasing the degree of freedom in design, and reducing Q and increasing stray capacitance compared to using a shielded coil of the same size or cost. The problem does not arise,
Therefore, there is no reduction in the level of the received signal or in the interference signal suppression effect, and the device can be miniaturized and realized at low cost.

[Brief explanation of the drawing]

FIG. 1 is a front view of an inductor 8 according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the cutting plane line - in FIG. 1, and FIG. 3 is a front view of an inductor 10 according to another embodiment of the present invention. A front view, FIG. 4 is a block diagram of a radio receiver equipped with an inductor 8, FIG. 5 is a block diagram of a receiver equipped with an inductor 8,
FIG. 6 is a block diagram showing a specific configuration of the AM receiving circuit 21, and FIG. 7 is a block diagram showing a specific configuration of the AM receiving circuit 21a. 1, 3, 11, 13... core, 2, 4, 12,
14... Coil, 8, 10, 10... Inductor, 25, 29... Antenna, 21, 21a, 2
1b...AM receiving circuit, 22...FM receiving circuit,
26...Capacity.

Claims (1)

[Scope of utility model registration request] An inductor that is connected between an antenna and a receiving circuit and suppresses the inflow of high-frequency signals other than the compatible frequency band among high-frequency signals from the antenna, the inductor consisting of two coils arranged in parallel, An inductor for a receiver, characterized in that the coils are connected in series or in parallel so that the polarities of alternating current electromotive force in the same alternating magnetic field are opposite.