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Semiconductor integrated circuit device and wireless communication systemRelated Patent Categories: Telecommunications, Receiver Or Analog Modulated Signal Frequency Converter, Local Control Of Receiver Operation, Gain Control, Automatic, SemiconductorSemiconductor integrated circuit device and wireless communication system description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070093225, Semiconductor integrated circuit device and wireless communication system. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] The present invention relates to a semiconductor integrated circuit, particularly a semiconductor integrated circuit device for communication comprising an signal amplifying circuit which can select variable gains and a high-gain amplifying circuit for amplifying the reception signal of a wireless communication equipment and also relates to the technique which can effectively be applied to the wireless communication equipment such as a portable telephone comprising the same semiconductor integrated circuit device for communication. [0002] In the wireless communication equipment (mobile communication equipment) such as a mobile telephone and a portable telephone, a low-pass filter and again control amplifier are provided for the purpose that a baseband circuit amplifies weak reception signal up to the predetermined level enough for realizing various processes while it is eliminating noise and unwanted frequency signals. [0003] In general, in the portable telephone of the conventional GSM (Global System for Mobile Communication) and DCS (Digital Cellular System), a step amplifier which can change step by step the gain depending on the reception signal level is used as a gain control amplifier. Meanwhile, in the portable telephone of the W-CDMA (Wideband Code Division Multiple Access) system, a linear amplifier which can linearly control the gain is proposed as an amplifier for amplifying the reception signal. SUMMARY OF THE INVENTION [0004] In comparison of a step amplifier with a linear amplifier, the linear amplifier exhibits large fluctuation of power consumption because gain is varied with current, but the step amplifier has a merit that power consumption of battery can be reduced in the system driven with a battery because power consumption does not change to a large extent even if gain is varied. Moreover, the linear amplifier has a disadvantage that the gain control range is narrower than that of the step amplifier and the amplifier may be saturated in the high-gain range to result in distortion of signal. [0005] Even when such a disadvantage is considered, the linear amplifier is still used for the portable telephone in the W-CDMA system based on the major reason that the input DC offset of amplifier must be cancelled whenever the gain is varied in the step amplifier but there is no time for canceling the DC offset in the W-CDMA system because the continuous receiving operation is required. Meanwhile, in the portable telephone of the GSM system and DCS system, the step amplifier can be used because the transmission mode and reception mode are switched in the unit of time (for example, 577 .mu.S) called the time slot and DC offset can be cancelled at the time of switching the transmission mode and reception mode. [0006] The inventors of the present invention have investigated the possibility for common use of the amplifier to amplify the reception signal in both systems in order to develop the dual-mode portable telephone of the W-CDMA system and GSM system and have reached the conclusion that common use is difficult because the types of amplifiers are different as described above. The present invention has been attained in the course of investigation of the common use of receiving amplifier. [0007] There has been proposed the invention disclosed in the Japanese Patent Unexamined Publication No. Hei 9(1997)-64666 as the technique similar to the present invention but the present invention is different from such prior art in the purpose and condition for switching of the amplifier. [0008] An object of the present invention is to provide a semiconductor integrated circuit device to form a wireless communication system of the dual or more modes including the W-CDMA system which can use a step amplifier as the gain control amplifier to amplify the reception signal, thereby to keep power consumption to almost constant value even when the gain is changed depending on the intensity of reception signal and to assure longer battery life in the portable telephone, namely longer reception waiting period and communication period through single charging process. [0009] Another object of the present invention is to provide a semiconductor integrated circuit device and a wireless communication system using the same circuit device which can widen the gain control range of gain control amplifier to amplify the reception signal in order to improve the CN ratio. [0010] The aforementioned and the other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings. [0011] The typical inventions disclosed in the present specification will be briefly described as follows. [0012] Namely, the first invention of the present specification relates to the semiconductor integrated circuit device for wireless communication system for continuous reception while the gain is changed as in the case of the W-CDMA system, in which a step amplifier is used as the gain control amplifier to amplify the reception signal, and two step amplifiers are provided and are controlled for alternative operation, and if the gain is switched, the amplifier to which the reception signal is inputted is switched after the gain is switched with the step amplifier not operated and the offset is cancelled. [0013] According to the means described above, since a step amplifier is used as the gain control amplifier, power consumption can be set almost to the constant value even when the gain is changed depending on the intensity of reception signal and moreover since two step amplifiers are provided to change the gain and the input reception signal is switched after the cancellation of offset, missing of the receiving data due to the offset canceling operation can be eliminated even if the signal can be received continuously. [0014] The second invention of the present specification relates to the semiconductor integrated circuit device for wireless communication system for dual-mode or more modes including the mode for continuous reception while the gain is changed as in the case of the W-CDMA system, in which a step amplifier is used as the gain control amplifier for amplifying the reception signal, a plurality of filter circuits for removing unwanted frequency and noise are provided depending on the frequency of each mode, the filter circuit is switched depending on the selected mode, and thereby switching of gain and canceling of offset are performed almost simultaneously. Here, the mode means the communication system of different multiplexing system and modulation system such as the GSM system, DCS system and W-CDMA system. Since the GSM system and DCS system are identical in the multiplexing system and modulation system but are different only in the frequency band used, these are considered as the same mode in this specification. [0015] According to the means described above, since a step amplifier is used as the gain control amplifier, power consumption can be controlled almost to the constant value even when the gain is changed depending on the intensity of reception signal and moreover in the mode including the function for repairing the receiving data, for example, such as the W-CDMA system, any problem does not occur in the receiving operation because if a part of the receiving data is lost, such missing data can be recovered by switching the gain and canceling the offset during the receiving operation. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 is a block diagram illustrating an example of structure of a receiving system circuit of a portable telephone as the first embodiment to which the present invention is suitably applied. [0017] FIG. 2 is a block diagram illustrating an example of structure of high-gain amplifier unit of the receiving system circuit of FIG. 1. [0018] FIG. 3 is a circuit diagram illustrating a practical circuit example of step amplifier used as the gain control amplifier of the receiving system circuit of FIG. 1. [0019] FIG. 4 is a circuit diagram illustrating an example of the other circuit of the step amplifier used as the gain control amplifier of the receiving system circuit of FIG. 1. [0020] FIG. 5 is a circuit diagram illustrating an example of the gain control amplifier and DAC circuit for calibration of the receiving system circuit of FIG. 1. [0021] FIG. 6 is a timing chart illustrating an example of the control timing when the gain is changed in the high-gain amplifying unit depending on the level of reception signal. Continue reading about Semiconductor integrated circuit device and wireless communication system... Full patent description for Semiconductor integrated circuit device and wireless communication system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Semiconductor integrated circuit device and wireless communication system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Semiconductor integrated circuit device and wireless communication system or other areas of interest. ### Previous Patent Application: Method and apparatus for calibrating filtering of a transceiver Next Patent Application: Precisely timed execution of a measurement or control action and synchronization of several such actions Industry Class: Telecommunications ### FreshPatents.com Support Thank you for viewing the Semiconductor integrated circuit device and wireless communication system patent info. IP-related news and info Results in 0.10543 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
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