Amplifiers – Combined with automatic amplifier disabling switch means
Reexamination Certificate
2001-08-27
2003-10-21
Tokar, Michael (Department: 2819)
Amplifiers
Combined with automatic amplifier disabling switch means
C330S129000, C330S133000, C330S134000, C330S285000, C330S289000
Reexamination Certificate
active
06636114
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a high frequency power amplifier module having a plurality of amplifying systems, for example, a high frequency power amplifier device (high frequency power amplifier module) capable of performing linear amplification and non-linear amplification (saturation amplification) and a wireless communication apparatus in which the high frequency power amplifier module is built therein, and particularly to a technology effective for application to a cellular portable phone of a multi-mode and multi-band communication scheme or system, which has a plurality of communication functions different from one another in communication mode and frequency band.
In a North American cellular market, a single cellular phone, a so-called dual mode portable phone has recently been used wherein a digital system such as an analog type AMPS (Advanced Mobile Phone Service) covering the whole of North America, which has heretofore been used, TDMA (Time Division Multiple Access), CDMA (Code Division Multiple Access) or the like is built therein.
On the other hand, a GSM (Global System for Mobile Communication) system using a TDMA technology and an FDD (Frequency Division Duplex) technology has been used in Europe or the like. An EDGE (Enhanced Data Rates for GSM Evolution) system has been developed as a communication system in which a transfer rate can be made high in the GSM system.
The EDGE has been described in “Nikkei Electronics” published by Nikkei Business Publications, Inc., the Nov. 15, 1999 (no.757), P131, and the Jul. 3, 2000 (no.773), P126 to P139 of the same issue.
The former reference has described a speeded-up mobile communication service in various parts of the world. The present reference describes that the mobile communication service transitions from the second generation of ~9.6 kbits/second to the third generation of ~2 Mbits/second. Further, the reference describes that in Europe, the mobile communication service transitions to an EDGE (third generation) through a GPRS (General Packet Radio Service: 2.5th generation) corresponding to a data communication service based on packet communications in which the existing GSM network is expanded, whereas in the USA, the mobile communication service transitions from an IS-136 system (TDMA) to the EDGE and from an IS-95 system (CDMA) to a cdma2000, an IS-2000 and an HDR (High Data Rate).
The latter reference describes a size reduction in a wireless circuit of a cellular phone. Further, the reference describes that a control technology wherein a plurality of channels can simultaneously be used in a high-speed data transmission or communication service, has been developed, and also describes that in a system EDGE dedicated for a GSM-based data communication service, a modulation scheme is changed from GMSK to eight-phase PSK to increase frequency availability, thereby implementing 384 kbits/second. Furthermore, the same reference discloses a reference board for a GSM cellular phone using a chip set of a superheterodyne system and a direct conversion system.
On the other hand, a multi-mode communication made by a dual mode cellular phone or the like has been described in “Nikkei Electronics” published by Nikkei Business Publications, Inc., the Jan. 27, 1997 (no.681), P115 to P126, and “Hitachi Review” published by Hitachi Review Inc., the November 1997 issue, Vol. 79, P63 to P68. The latter reference discloses an offset PLL (Phase-Locked Loop) method or system for the conversion of a transmit frequency on the transmitting side.
SUMMARY OF THE INVENTION
While lots of wireless data communications using mobile radio have heretofore been carried out at a transmission rate of 9.6 kbps, accessing to an Internet and corporate databases needs to have a higher transmission rate and hence a communication system corresponding to it has been required. While the GSM system furnishing services with Europe and Asia as principal parts, provides 9.6 kbps-based services under the present situation, an EDGE system in which a transmission rate has been set high, has been developed to meet the above request. Introducing this type of system makes it possible to increase the data transmission rate to 384 kbps and transmit data equivalent to 40 times per unit time to the GSM system.
Another advantage of the EDGE system resides in that since the EDGE system can be introduced by appropriating the basic system of GSM and partly changing a radio modulation system or scheme, it can be operated without introducing infrastructure. This would be attractive for many communication common carriers.
The modulation scheme to be changed serves as a system in which 3&pgr;/8-rotating8PSK (Phase Shift Keying) modulation is used in the EDGE system with respect to GMSK (Gaussian Minimum Shift Keying) modulation of the GSM system. Thus, a signal transmission unit of a wiring apparatus needs to have higher linearity.
Since the EDGE system is a system in which the GSM system has been upbuilt, it is desirable that a single cellular phone is capable of making phone calls through the use of the GSM system and the EDGE system. It is therefore necessary to incorporate an amplifier for the GSM system and an amplifier for the EDGE system in the cellular phone.
The present inventors have discussed a high frequency power amplifier module wherein one amplifier circuit copes with the GSM system and the EDGE system. As a result, the present inventors have found the following problems to be solved.
(1) When the high frequency power amplifier module is used in GSM, the corresponding transistor is used in a saturated operation and hence a large output is required. Namely, an output power of about 36 dBm at maximum is necessary for a GMSK-modulated input signal of about 0 dBm, for example.
(2) When it is used in EDGE, the transistor is used in a linear operation and hence linearity is required for it. Namely, an output signal needs to be undistorted with respect to a 3&pgr;/8-rotating 8PSK-modulated input signal. The maximum of linear output power ranges from about 28 dBm to about 29 dBm.
(3) In the GSM system and the EDGE system, a large difference occurs in their output power as described above as in the case where the maximum power ranges from 6 dBm to 8 dBm, and they differ in amplification class (Class A and Class C). Therefore, when the single amplifier is shared therebetween, lots of noise are produced and controllability becomes low due to the difference in gain therebetween.
An object of the present invention is to provide a high frequency power amplifier module and a wireless communication apparatus, which are capable of causing a saturation-operated system and a linearly-operated system to coexist with each other within the same circuit.
Another object of the present invention is to provide a high frequency power amplifier module and a wireless communication apparatus, which allow a GSM system (saturation operation) and an EDGE system (linear operation) to coexist with each other within the same circuit.
A further object of the present invention is to provide a high frequency power amplifier module and a wireless communication apparatus, which have plural modes/plural bands configurations.
The above, other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
Summaries of typical ones of the inventions disclosed in the present application will be described in brief as follows:
(1) There is provided a high frequency power amplifier module comprising:
an input terminal supplied with a signal to be amplified;
an output terminal;
a control terminal;
a mode switch terminal;
a plurality of amplifying stages cascade-connected between the input terminal and the output terminal,
the plurality of amplifying stages respectively comprising first terminals each of which receives a signal inputted to each amplifying stage, second terminals each of which transmits a signal outputted therefrom, and third terminals each of which receives a reference poten
Adachi Tetsuaki
Tsutsui Takayuki
Hitachi , Ltd.
Miles & Stockbridge P.C.
Nguyen Linh Van
Tokar Michael
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