Wave transmission lines and networks – Coupling networks – Nonreciprocal gyromagnetic type
Reexamination Certificate
2002-01-22
2003-11-11
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
Nonreciprocal gyromagnetic type
C333S001100
Reexamination Certificate
active
06646517
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a nonreciprocal circuit device, and, more particularly, to a nonreciprocal circuit device such as an isolator for use in the microwave band, and to a communication device.
2. Description of the Related Art
FIG. 13
is an electrical-circuit block diagram of an RF portion of a conventional portable phone
1
. In
FIG. 13
, reference numeral
2
denotes an antenna element. Reference numeral
3
denotes a duplexer Reference numerals
4
and
6
each denote a power amplifier on the transmission side. Reference numeral
5
denotes an interstage band-pass filter on the transmission side. Reference numeral
7
denotes a mixer on the transmission side. Reference numeral
8
denotes a low-noise amplifier on the receiving side. Reference numeral
9
denotes an interstage band-pass filter on the receiving side. Reference numeral
10
denotes a mixer on the receiving side. Reference numeral
11
denotes an isolator. Reference numeral
12
denotes a voltage-controlled oscillator (VCO). Reference numeral
13
denotes a local band-pass filter.
Generally, the isolator
11
is disposed between the voltage-controlled oscillator
12
and the mixers
7
and
10
on the transmission and receiving sides in order to achieve isolation between the voltage-controlled oscillator
12
and the mixers
7
and
10
on the transmission and receiving sides, so that signals reflected from the mixers on the transmission and receiving sides are not returned to the voltage-controlled oscillator. Instead of the isolator
11
, a buffer amplifier is sometimes used. However, since the isolator
11
of a nonreciprocal circuit device does not require power, the battery life is not affected by the isolator, so the isolator
11
has the advantage that the standby time and the telephone conversation time of the portable phone
1
can be increased.
As there has been a demand for smaller portable phones and to achieve cost reduction in recent years, ICs incorporating the mixer
7
on the transmission side and the mixer
10
on the receiving side (which are balanced input/output circuits) have become more and more common. However, the input/output ports of a conventional isolator
11
are both unbalanced-type ports. Therefore, in order to electrically connect to the isolator
11
the balanced-type input/output ports of an IC in which a mixer is incorporated, it is necessary to convert a parallel signal of the IC to a single ended signal by using a balun. For this reason, the number of components is increased, and the number of connection points is increased, presenting problems of radiation, resistive losses, and greater mounting area and failure rate, for example.
SUMMARY OF THE INVENTION
To address these problems, the present invention provides a nonreciprocal circuit device which can be connected to a balanced circuit without going through a balun, and a communication device.
The nonreciprocal circuit device according to the present invention may have two ports, wherein at least one of the two ports is a balanced-type port. For example, there are cases in which only the input port is a balanced-type port, or only the output port is a balanced-type port, or both the input port and the output port are balanced-type ports.
More specifically, the nonreciprocal circuit device may comprise a center electrode assembly formed of a ferrite and two center electrodes, a permanent magnet for applying a DC magnetic-field to the ferrite, and a metal case for housing the center electrode assembly and the permanent magnet. The balanced-type port is formed of a pair of terminals which are electrically connected respectively to the two ends of a line that is substantially a half-wave in length at an operating frequency, and one of the pair of terminals is connected to one of the center electrodes. Furthermore, the balanced-type port is formed of a pair of terminals which are electrically connected to both ends of one of the center electrodes via a matching capacitor.
The nonreciprocal circuit device having the above construction can be connected to a balanced circuit without going through a balun.
The communication device according to the present invention comprises a nonreciprocal circuit device having the above-described features, and therefore, high reliability can be obtained.
Further features and advantages of the present invention will become apparent from the following description of embodiments of the invention with reference to the attached drawings.
REFERENCES:
patent: 3614675 (1971-10-01), Konishi
patent: 3906404 (1975-09-01), Dixon, Jr.
patent: 5628057 (1997-05-01), Phillips et al.
patent: 5638033 (1997-06-01), Walker et al.
Hino Seigo
Kawashima Makoto
Shimmura Satoru
Jones Stephen E.
Keating & Bennett LLP
Lee Benny
Murata Manufacturing Co. Ltd.
LandOfFree
Nonreciprocal circuit device and communication device having... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Nonreciprocal circuit device and communication device having..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nonreciprocal circuit device and communication device having... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3183778