JPH042223A - Receiver - Google Patents

Abstract

PURPOSE:To control the induction of an RF signal and to prevent the deterioration in the reception characteristic by covering the filter and the mixer of a receiver incorporated with an antenna thereto in a case with a shield case. CONSTITUTION:Each section except an antenna 1 built in the case of a receiver is assembled normally on a printed circuit board and each section is contained in the case made of a resin or the like together with the antenna 1 on the printed circuit board. Then a 1st filter 3, a 2nd filter 5 and a mixer 6 are arranged on the printed circuit board close to each other, and the region where the filters 3, 5, the mixer 6 and interconnecting wires are included is covered by a shield case 10 such as a metallic base. Thus, the induction of an RF signal is suppressed and the deterioration in the reception characteristic is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a receiver such as a paging receiver used in mobile communications.

[Conventional technology]

As shown in Fig. 2, a conventional receiver of this type includes an antenna 1 built into a case, an RF amplifier 2 that amplifies the RF signal induced in the antenna 1, and an RF signal that is amplified by the RF amplifier 2. a first filter 3 that filters the RF multiplied signal;
A local oscillator 4, a second filter 5 that filters the local oscillator signal from the local oscillator 4, and an RF multiplied local oscillator signal from the first and second filters 3 and 5 are mixed. a mixer 6 for obtaining an intermediate frequency signal; and a third mixer for filtering the intermediate frequency signal.
The intermediate frequency amplifier 8 amplifies the intermediate frequency signal and limits its amplitude, and the demodulator 9 demodulates the intermediate frequency signal into a baseband signal.

[Problems to be Solved by the Invention] Incidentally, since such a receiver has a built-in antenna, the case cannot be constructed of a metal case. For this reason, the receiver may receive the RF multiplied signals induced by sources other than the antenna together.
This causes the problem that complex characteristics are exhibited and desired reception characteristics cannot be obtained.

As for this induced RF multiplied signal, for example, the first and second filters 3 and 5 and the mixer 6 are connected through wiring on the printed circuit board, so each part responds to the received radio wave. They are not at the same potential, and there is an induced voltage generated between them. Therefore, it becomes difficult to sufficiently activate the original function of the first filter 3 for removing this type of interference wave, resulting in deterioration of reception characteristics.

An object of the present invention is to provide a receiver that suppresses such RF multiplication signal induction and prevents deterioration of reception characteristics.

[Means to solve the problem]

The receiver of the present invention has a built-in antenna, and includes an RF amplifier, a filter 1 local oscillator, a mixer 2 intermediate frequency amplifier, a demodulator, etc. in a case, and at least part of the filter. The container and the mixer are covered with a shield case inside the case.

For example, an antenna, an RF amplifier that amplifies the RF signal induced in the antenna, and the R
a first filter that filters the F-fold signal; a local oscillator; a second filter that filters the signal from the local oscillator; and a second filter that filters the signal from the RF-multiplied signal local oscillator. a mixer for mixing, a third filter for filtering the intermediate frequency signal output from the mixer, an intermediate frequency amplifier for amplifying the filtered intermediate frequency signal, and a third filter for filtering the intermediate frequency signal output from the mixer; In the case of a receiver configured with a demodulator that demodulates a band signal, the first filter, the second filter, and the mixer are covered with a shield case.

[Effect]

According to the present invention, by shielding the filter, the mixer, and the wiring connecting them from an external electric field with the shield case, induction of an RF multiplied signal in each of these parts is prevented.
Deterioration of reception characteristics is prevented.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and the same parts as the conventional configuration shown in FIG. 2 are given the same reference numerals. That is, in the figure, 1 is an antenna built into the receiver case, 2 is an RF amplifier, 3 is a first filter, 4 is a local oscillator, 5 is a second filter, and 6 is a mixer. 7 is a third filter, 8 is an intermediate frequency amplifier, and 9 is a demodulator.

Of these, each part except the antenna 1 is usually assembled on a printed circuit board, and then housed together with the antenna 1 in a case made of resin or the like.

and the first filter 3. The second filter 5 and mixer 6 are arranged in close proximity to each other on the printed circuit board, and the area containing the filter and mixer and the wiring interconnecting them is covered with a metal case. etc. shield case 1
covered by 0.

According to this configuration, the RF multiplied signal induced by the antenna 1 is amplified by the RF amplifier 2, enters the first filter 3 in the shield case 10, is filtered, and is then input to the mixer 6.

On the other hand, the local signal from the local oscillator 4 is transmitted to the shield case 1.
After being filtered by the second filter 5 within 0, the signal is input to the mixer 6.

The RF multiplied signal local signal is mixed by a mixer 6, converted into an intermediate frequency signal, inputted to a third filter 7 that filters the intermediate frequency outside the shield case 10, and after being filtered, the intermediate frequency signal is It is input to amplifier 8. The intermediate frequency amplifier 8 amplifies the intermediate frequency signal, limits its amplitude, and then guides it to the demodulator 9 for demodulation. The demodulator 9 demodulates the baseband signal and uses it.

Furthermore, here, the first filter 3. Second filter5.
Since the mixer 6 and the mixer 6 are covered with the shield case 10, the inside of the shield case 10 has the same potential, and even when an external electric field affects the receiver, the first and second filters 3, 5 or mixer6. And the wiring connecting each of them is shielded from an external electric field, and the voltage induced in each of these parts is extremely small. Therefore, deterioration of reception characteristics caused by this type of induced voltage can be prevented, and a receiver with stable characteristics can be obtained.

In particular, when using 5AW (acoustic wave) filters as the first and second filters 3, 5, it becomes possible to mount these filters 3, 4 and mixer 6 in a small can case. The effect is great.

[Effects of the Invention] As explained above, the present invention covers the filter 2 local oscillator, etc. of a receiver with a built-in antenna in the case with a shield case, so that the filter, mixer, etc. The receiver and the wiring connecting them can be shielded from an external electric field by a shield case, and RF multiplied signals can be prevented from being induced in these parts, thereby preventing deterioration of reception characteristics.

Therefore, in the field of mobile communication where the demand for radio waves will increase gradually in the future, deterioration of characteristics due to the influence of interference waves etc. will become apparent, and the present invention will be effective even in such cases.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the receiver of the present invention, and FIG.
The figure is a block diagram of a conventional receiver. 1... Antenna, 2... RF amplifier, 3... First
filter, 4... Local oscillator, 5... Second filter, 6... Mixer, 7... Third filter, 8... Intermediate frequency amplifier, 9 ... Demodulator, 10... Shield case. Figure 2

Claims (1)

[Claims] 1. In a receiver having a built-in antenna and an RF amplifier, a filter, a local oscillator, a mixer, an intermediate frequency amplifier, a demodulator, etc. inside the case, at least part of the filtering 1. A receiver characterized in that a receiver and a mixer are covered with a shield case within the case. 2. An antenna, an RF amplifier that amplifies the RF signal induced in the antenna, a first filter that filters the RF signal amplified by the RF amplifier, a local oscillator, and a signal from the local oscillator. a second filter that filters the RF signal, a mixer that mixes the filtered RF signal and the signal from the local oscillator, and a third filter that filters the intermediate frequency signal output from the mixer. an intermediate frequency amplifier that amplifies the filtered intermediate frequency signal, and a demodulator that demodulates the baseband signal from the amplified intermediate frequency signal, the first filter and the second filter and a receiver consisting of a mixer covered with a shield case.