| Semiconductor integrated circuit device and wireless communication system -> Monitor Keywords |
|
|
 
Semiconductor integrated circuit device and wireless communication systemRelated Patent Categories: Telecommunications, Transmitter, Power Control, Power Supply, Or Bias Voltage Supply, Gain Control, Plural Amplifier StagesSemiconductor integrated circuit device and wireless communication system description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060293004, Semiconductor integrated circuit device and wireless communication system. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present application is a continuation of application Ser. No. 10/685,481, filed Oct. 16, 2003, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates to a wireless communication technology, more specifically to a technology which may be effectively applied, while increase of power consumption is controlled, for improving linearity of a semiconductor integrated circuit device comprising an amplifying circuit to amplify the code division multiplexed transmitting signal. Moreover, the present invention relates to a technology which may be effectively applied to a semiconductor integrated circuit device for communication constituting a wireless communication device, for example, of W-CDMA (Wideband Code Division Multiple Access) system and to a wireless communication device such as a mobile telephone or the like comprising the same semiconductor integrated circuit device. [0003] In the wireless communication device such as a mobile telephone (mobile communication device), a multiplex system is employed to increase the amount of data to be transmitted. The present multiplex system used for the mobile telephone includes a TDMA system (time division multiplex system) and a CDMA system (code division multiplex system) or the like. The CDMA system is a communication system where a plurality of diffused codes having orthogonality in the same frequency space are used for spectrum diffusion of carrier and the diffused carriers are assigned to a plurality of channels. The CDMA system is employed for the mobile telephone of the W-CDMA system. In the mobile telephone of the PDC (Personal Digital Cellular) system and GSM (Global System for Mobile Communication) system, the TDMA system is employed. [0004] In the mobile telephone of W-CDMA system, the I, Q signals generated based on the transmission data in a baseband circuit are supplied to a transmitting circuit including a modulation circuit, the signals obtained by modulating a local oscillation signal with the I, Q signals are supplied to a power amplifier for the power amplification and finally the amplified signals are outputted from an antenna. For the mobile telephone of the W-CDMA system, there is provided a system where level and accuracy of an average output power corresponding to the output request level transmitted from a base station are determined by the specification, gain of a power amplifier is controlled with an output control signal supplied from the baseband circuit, and signals are transmitted in the specified output power. SUMMARY OF THE INVENTION [0005] In the specification of the mobile telephone of the W-CDMA system, it is specified that the data of six channels in maximum can be transmitted from one channel through the multiplexing, but this method has problems that the more the number of multiplexes of data is increased, the more the distortion of transmission signal increases and thereby the ACPR (leak power ratio to the adjacent channel) characteristic is deteriorated. Therefore, the inventors of the present invention have investigated causes of these problems. As a result of the investigation, it has become apparent that the number of multiplexes of data is closely related to peak factor and the peak factor becomes larger as the number of multiplexes increases. Here, the peak factor is a difference between the maximum peak value of the transmission signal (momentary maximum power) and an average output level. [0006] FIGS. 13(A) and 13(B) illustrate waveform images of the transmission signals when the number of multiplexes is "1" and "6" in the W-CDMA system. In these FIGS. 13(A) and 13(B), "ave" is an average output level which is determined with an output control voltage. In the specification of the mobile telephone of the W-CDMA system, even when the average output level ave is identical as illustrated in FIGS. 13(A) and 13(B), the peak factor when the number of multiplexes is "6" becomes larger than that when the number of multiplexes is "1". FIG. 14 illustrates the relationship between the number of multiplexes and peak factor in the mobile telephone of the W-CDMA system. From FIG. 14, the peak factor is about 3 dB when the number of multiplexes is "1", but it increases up to 7.5 dB when the number of multiplexes is "6". [0007] Moreover, it has been found when the transmission signal is amplified with an amplifying circuit having a narrower dynamic range with the peak factor which is large as described above, distortion of signal increases and the ACPR characteristic is deteriorated. Therefore, the inventors of the present invention have thought to design an amplifying circuit having wider dynamic range to amplify the transmission signal in order to obtain the IPC (1 dB Compression Point) for transmission of signal without distortion even when the maximum number of multiplexes is "6". [0008] It is generally known that a wide dynamic range of the amplifying circuit can be obtained by increasing a current flowing into the circuit. However, since power consumption of the total system increases when the current of the amplifying circuit increases, it is a problem to be eliminated as much as possible in the system such as a mobile telephone which is operated with a battery. Particularly, since the transmitting operation is executed separately from the receiving operation in the mobile telephone of the time division multiplex system like a PDC, the current consumption is not so large. However, in the mobile telephone of the W-CDMA system, since the transmitting operation and receiving operation are executed simultaneously and continuously, current consumption is considerably larger than that of the mobile telephone of the PDC system. Therefore, increase in current of the amplifying circuit in the mobile telephone of the W-CDMA system will result in the problem that the maximum communication time and the maximum waiting time which are intrinsically short may be further shortened. [0009] As the prior art of the present invention, there is the Japanese Published Unexamined Patent Application No. 270733/1997. This prior art is intended to realize low power consumption by changing accuracy of arithmetic operations of a band-pass filter depending on the information about number of channels to be multiplexed. Therefore this prior art seems to be similar to the present invention when attention is paid to reduction of power consumption by switching the circuits based on the information about the number of multiplexes of the signals. [0010] However, the present invention relates to a mobile telephone but this prior art relates to a transmitter in the base station side. Moreover, in the present invention, the information used for control is the number of multiplexes of data to be transmitted, while such data is the number of multiplexes of channel, namely the number of mobile terminals for communication in the prior art. In addition, the control object circuit to be switched is the dynamic range of a differential amplifier (analog circuit) in the present invention but it is the number of taps in the band-pass filter (digital filter) in the prior art. Therefore, the prior art is the invention which is obviously different from the present invention. [0011] An object of the present invention is to realize, in a wireless communication system which performs multiplexing of signals with spectrum diffusion such as a W-CDMA system, that a signal can be transmitted without distortion even when the number of multiplexes is increased and a current of an amplifying circuit can be reduced to result in lower current consumption when the number of multiplexes is small and thereby the operation life of a battery, namely the maximum communication time and the maximum waiting time based on the single charging cycle can be extended considerably when the present invention is applied to a mobile telephone. [0012] Another object of the present invention is to provide a semiconductor integrated circuit device for communication to form a wireless communication system of the code division multiplex system which can improve the ACPR (leak power ratio to the adjacent channel) characteristic, and to provide a wireless communication system using the same semiconductor integrated circuit device. [0013] The aforementioned and the other objects and novel features of the present invention will become apparent from description of the present specification and the accompanying drawings. [0014] First, a problem in the transmission system of the mobile telephone of the W-CDMA system to which the attention of the inventors has been paid and a method of solving the problem of the present invention will be described. [0015] In the W-CDMA transmission system, the signals (sin wave and cos wave) of the predetermined frequency in the phases with difference of 90.degree. are subjected to the BPSK modulation with the control data DPCCH and user data DPDCH to generate I and Q signals, and these signals are diffused in the spectrum with the channelization code in the rate of 3.84 Mcps. When the user data DPDCH is "0", the I signal modulated only with the control data DPCCH is generated and this signal is spectrum-diffused. When the user data DPDCH is "3", the control data DPCCH and one of the user data, for example, DPDCH2 are assigned to the Q signal. Moreover, the remaining two data DPDCH1, DPDCH3 of the user data are assigned to the Q signal for modulation. Thereafter, the signal is spectrum-diffused. Generation of the I signal and Q signal, namely multiplex described above is performed in the circuit called the baseband circuit. [0016] FIGS. 12(A) and 12(B) illustrate constellations indicating, on the IQ coordinates, position and changing direction of each symbol of the signal generated by the code division diffusing process (multiplex) performed by the baseband circuit. FIG. 12(A) corresponds to the constellation when the number of multiplexes is "1", while FIG. 12(B) corresponds to the constellation when the number of multiplexes is "6". From these figures, it is obvious that the probability for passing the origin when the number of multiplexes is "1" is higher than that when the number of multiplexes is "6". Here, since the fact that a symbol shifts to the other symbol passing the origin means that the phase changes for 180.degree., amount of protrusion to the external side from the position of the target symbol becomes larger than that of the other case. Increase in amount of protrusion is a cause of enlargement of the peak factor of the transmission signal as illustrated in FIGS. 13(A) and 13(B). [0017] In the W-CDMA system, diffusion is executed twice as specified in the specification, but the HPSK modulation is performed when the second diffusion is executed. Accordingly, probability for passing the origin in the IQ constellation may be reduced, the peak factor may be kept small and the linearity required for transmitting circuit may also be alleviated. However, when the number of multiplexes, namely the number of user data DPDCH increases, effect of the HPSK modulation is lowered. Therefore, it is thought that probability for passing the origin in the constellation increases and thereby the peak factor is increased. [0018] FIG. 14 illustrates the relationship between the number of multiplexes and the peak factor in the transmission signal of W-CDMA system in the form of a graph based on the simulation and actually measured values. From FIG. 14, it is known that the peak factor increases rapidly when the number of multiplexes exceeds "3". Therefore, when the peak factor becomes large, since distortion of signal becomes large when the linearity of circuit to transmit the signal is not sufficient, the linearity of the transmission circuit must be improved. [0019] As an index indicating linearity of circuit, an index called IPC (1 dB compression point) which indicates characteristic for transmission without distortion of signal is used. Hereinafter, this index is used in the description. Moreover, since it is known that the third order intercept point IP3 and saturation power Psat are also related to the ICP to a certain degree, the ICP in the description of the specification may be replaced with IP3 or Psat. [0020] For transmission of a multiplex signal without any distortion, the range of linear characteristic of the transmission circuit, namely the dynamic range is generally widened as much as the peak factor. Namely, the signal can be amplified without distortion even when the number of multiplexes is "6" by designing a circuit of variable gain amplifying portion enough to accept the maximum level (maximum peak factor) to be inputted to the circuit. In more practical, it is understood from FIG. 14 that the peak factor when the number of multiplexes is "6" is increased by about 4.5 dB in comparison with the case where the number of multiplexes is "1". Therefore, when the ICP of the circuit is improved by 4.5 dB, deterioration of distortion characteristic due to increase in the number of multiplexes can is be eliminated. [0021] However, the maximum peak voltage which is a factor of peak factor is comparatively small and appears in average when the number of multiplexes is small as can be understood from FIG. 13(A), but when the number of multiplexes increases, the maximum peak voltage is no longer average and appears at random in the large value and small value with less appearing frequency of the comparatively large value as can be understood from FIG. 13(B). Accordingly, it is most desirable that IPC of the transmission circuit is improved by 4.5 dB in accordance with the peak factor. However, it is thought enough for practical use when the IPC is improved by about 3 dB. [0022] FIG. 15 illustrates relationship between a current and 1 dB compression point ICP in the variable gain amplifying portion of a general code division multiplex transmission circuit in the mobile telephone of the W-CDMA system. From FIG. 15, it can be understood that the ICP can be increased by 3 dB by increasing a current of the variable gain amplifying portion by 100%. 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: High-efficiency modulating rf amplifier Next Patent Application: Wireless transmission apparatus, polar modulation transmission apparatus, and wireless communication apparatus 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 0.14518 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
