Wave transmission lines and networks – Coupling networks – Frequency domain filters utilizing only lumped parameters
Reexamination Certificate
1999-01-13
2001-01-23
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
Frequency domain filters utilizing only lumped parameters
C333S202000, C333S205000
Reexamination Certificate
active
06177850
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a filter for use in mobile communication apparatuses, such as portable or mobile telephones, that conform to the use for plural high-frequency bands.
2. Description of the Related Art
Hitherto, when two high-frequency bands of mobile communications are relatively adjacent to each other as in a case of a 900-MHz GSM (global system for mobile communications) and a 1.8-GHz DCS (digital cellular system), two mobile communication systems share a single antenna.
FIG. 10
is a block diagram showing a structure in which two communication systems share a single antenna. In
FIG. 10
,
51
refers to an antenna,
52
refers to a duplexer,
53
refers to a GSM-side switch, and
54
refers to a DCS-side switch. The antenna
51
is connected to a first terminal
53
a
of the GSM-side switch
53
through the duplexer
52
, and a GSM transmitter circuit Txgsm and a GSM receiver circuit Rxgsm are connected to a second terminal
53
b
and a third terminal
53
c
, respectively. Furthermore, the antenna
51
is connected to a first terminal
54
a
of the DCS-side switch
54
through the duplexer
52
, and a DCS transmitter circuit Txdcs and a DCS receiver circuit Rxdcs are connected to a second terminal
54
b
and a third terminal
54
c
, respectively. The frequency band is thus separated for the GSM and the DCS through the duplexer
52
, and transmit/receive switching is performed by the GSM-side switch
53
and the DCS-side switch
54
. By this arrangement, transmitting-receiving communication between the two mobile communication systems GSM and DCS, sharing a single antenna, can be achieved.
However, in such a conventional structure sharing a single antenna, the antenna is connected to the GSM switch and the DCS switch through the duplexer, and through these switches, the antenna is further connected to the transmitter circuits and the receiver circuits; in which a problem arises with the increased number of constituent members. This problem makes it difficult to reduce the size of the mobile communication apparatus mounting the aforementioned constituent members.
SUMMARY OF THE INVENTION
To overcome the problems described above, preferred embodiments of the present invention provide a smaller-sized filter that is capable of functioning for high-frequency signals of plural frequency bands which are relatively adjacent to each other.
One preferred embodiment of the present invention provides a filter, comprising: at least one inductance device, at least one resonator, and at least one switching device. The inductance device may be connected in parallel with said switching device, and the resonator may be connected in series with the switching device.
According to the above described structure and arrangement, since it comprises an inductance device, a resonator, and a switching device, an equivalent circuit of a circuit formed of the inductance device, the resonator, and the switching device can be changed by controlling the voltage applied to the switching device. This allows the frequency band of high-frequency signals which pass through the filter to be changed; in which a single filter is enabled to sufficiently function for two high-frequency signals having two different frequency bands. Accordingly, mobile communication apparatuses having this filter can be smaller.
Furthermore, an antenna and a transmitting high-output amplifier can be shared by use of this filter in mobile communication apparatuses of plural frequency bands that are relatively adjacent to each other.
In the above described filter, the inductance device, the resonator, and the switching device may be disposed in or mounted on a multilayered body comprising a plurality of dielectric layers.
According to the above described structure and arrangement, since it is formed of a multilayered body, an inductance device, capacitance device, and switching device can be disposed in or mounted on the multilayered body. This allows the filter to be formed smaller.
In the above described filter, the resonator may be an open-stub resonator.
According to the above described structure and arrangement, it is not influenced by parasitic inductance of the pin diode; therefore, a greater insertion-loss attenuation can be established.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
REFERENCES:
patent: 4970479 (1990-11-01), Landt et al.
patent: 5065120 (1991-11-01), Munn
patent: 5065121 (1991-11-01), Ghadaksaz
patent: 5521561 (1996-05-01), Yrjöl{umlaut over (a)} et al.
patent: 5742215 (1998-04-01), Park
patent: 5783976 (1998-07-01), Furutani et al.
patent: 5-347541 (1993-12-01), None
patent: 9-200077 (1997-07-01), None
patent: 10-247833 (1998-09-01), None
Furutani Koji
Nakajima Norio
Tonegawa Ken
Lee Benny
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Summons Barbara
LandOfFree
Two frequency filter comprising an inductance device, a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Two frequency filter comprising an inductance device, a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two frequency filter comprising an inductance device, a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2519468