JP2007142680A - Transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize lower power consumption by so controlling operation current of VCO as to be a wanted C/N depending on transmission states. <P>SOLUTION: A PLL112 compares oscillation signal 118S of VCO109 with reference signal 115S for controlling the oscillation frequency of the VCO109 to a wanted frequency. After the output signal of the VCO109 is divided by dividers 105-108, modulation circuits 101-104 convert the divided signal into modulation signal for transmission. Here, an operation current control unit 111 controls the operation current that flows the VCO109 according to the transmission state of the modulation signal transmitted from the modulation circuits 101-104 (in other wards, transmission power, transmission frequency, band of transmission frequency, and the like). In short, the operation current control unit 111 reduces current consumption by so controlling the operation current of the VCO109 that the C/N of the VCO109 comes to be optimum. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmission device used for mobile communication, and more particularly to a transmission device that controls a transmission signal using a VCO (Voltage Controlled Oscillator).

  In mobile communication systems using mobile phones and the like, various modulation methods and frequency bands exist with the development of mobile communication, and the required specifications differ depending on each modulation method and frequency band. Terminal equipment has been developed. However, at present, in order to increase the number of users and improve convenience, there is an increasing demand for terminal devices that support multi-system and multi-band that can use a plurality of modulation schemes and frequency bands. However, in mobile communication, since there is a high demand for miniaturization from the viewpoint of portability, it is not possible to simply add parts. Therefore, for the miniaturization of mobile phones and the like, for example, one-chip integration is being attempted by integrating components such as transmission / reception ICs.

  FIG. 2 is a block diagram showing a configuration of a conventional transmission apparatus using a VCO. As shown in FIG. 2, the conventional transmission apparatus includes a VCO 9 that oscillates at a predetermined frequency, a reference oscillator 13 that outputs a reference signal 15S, an oscillation signal 18S and a reference signal 15S of the VCO 9 according to a frequency setting signal 14S, The PLL (Phased Locked Loop) 12 for controlling the oscillation frequency of the VCO 9 to the set frequency, the control unit 10 for sending the frequency setting signal 14S, and the oscillation signal 18S from the VCO 9 are divided. Frequency dividers 5-8, and modulation circuits 1-4 that receive the frequency-divided oscillation signal, convert the modulation signal 16S to a desired frequency, and output a transmission signal.

  In the transmission apparatus having such a configuration, the frequency setting signal 14S is calculated by the control unit 10 according to the transmission frequency and input to the PLL 12. The PLL 12 compares the reference signal 15S with the oscillation signal 18S from the VCO 9, and controls the oscillation frequency of the VCO 9 so that the frequency specified by the frequency setting signal 14S is obtained. By such control, the oscillation signal 18S output from the VCO 9 is frequency-divided by the frequency dividers 5-8 and input to the modulation circuits 1-4. Then, the modulation circuits 1 to 4 receive the oscillation signal output from the frequency dividers 5 to 8, convert the modulation signal 16S into a desired frequency, and output it as a transmission signal.

Note that such a transmission apparatus using a VCO is disclosed in, for example, Patent Document 1, Patent Document 2, and Patent Document 3.
JP 2005-94193 A JP 2005-72875 A JP 2005-12254 A

  By the way, one of the factors that determine the output spectrum of the transmitting apparatus is the C / N (Carrier to Noise Ratio) of the VCO. FIG. 3 is a spectrum characteristic diagram of the VCO by operating current, where the horizontal axis represents frequency and the vertical axis represents the level of the frequency component. In general, as shown in FIG. 3, the spectrum of the oscillation signal of the VCO changes according to the operating current. For example, as the operating current increases, the C / N tends to increase and improve. Therefore, when the C / N requirement is high, the operating current of the VCO is inevitably designed to be high.

  For example, when the GSM (Global System for Mobile) of a digital cellular phone system is described as an example, the modulation spectrum of the transmission wave is low as shown in FIG. 4 showing the specification of the modulation spectrum in GSM. Since it switches to the absolute value regulation at the time of output, the required specification of C / N becomes stricter at the time of high output. For example, in FIG. 4, the C / N at 400 kHz is 60 dB when the output level is 33 dBm. However, when the output level changes from 24 dBm or less to the absolute value regulation, the C / N is 56 dB at 20 dBm. / N requirements are getting stricter.

  Further, the C / N required does not change as the transmission frequency approaches the reception band, but the detuning frequency that requires the C / N becomes close and the C / N of the VCO becomes severe.

  Therefore, when the operating current of the VCO is designed so as to satisfy the required specifications at any transmission power and transmission frequency, the VCO at a low output or at a transmission frequency with a large frequency difference from the reception band. Consumes an excessive operating current, and as a result, the call time may be reduced due to battery consumption.

  Further, in the development of a multi-system / multi-band compatible terminal device, as shown in FIG. 2, a plurality of modulation circuits 1 to 4 are used from the viewpoint of miniaturization and cost reduction in integrating transmission / reception ICs into a single chip. However, at this time, the C / N required for the VCO 9 differs depending on each modulation method and frequency band. For example, in the case of multiband, a frequency divider having a different frequency division ratio is used to share the VCO. At this time, the C / N is improved by using a higher frequency division ratio, so that “Lo The C / N required for the VCO is lower when transmitting “-Band”.

  In the case of a multi-system, taking UMTS / GSM as an example, a broadband UMTS (Universal Mobile Telecommunication) has a lower C / N required for a VCO than a GSM. The C / N required for the VCO differs depending on the modulation method. Therefore, when designing according to the modulation method / frequency band with the highest C / N requirement, excessive current will be consumed in other modulation methods / frequency bands, resulting in fast battery consumption. As a result, the call time may be reduced.

  The present invention has been made in view of the above points, and provides a transmission apparatus that realizes low power consumption by controlling the operating current of a VCO so as to achieve a desired C / N according to a transmission state. Objective.

  The transmitter of the present invention compares the oscillation signal of the VCO with a reference signal in accordance with the frequency setting signal, modulates the PLL that controls the oscillation frequency of the VCO to the set frequency, and the output signal of the PLL. The transmission device includes a modulation circuit that transmits a signal, and has a configuration including an operation current control unit that controls an operation current flowing through the VCO according to a transmission state of a modulation signal transmitted from the modulation circuit. The transmission state of the modulation signal transmitted from the modulation circuit is a transmission power, a transmission frequency, or a transmission frequency band. Further, when a plurality of modulation schemes are realized by a plurality of modulation circuits by sharing one VCO, the operating current control means is configured to control the operating current flowing through the VCO according to each modulation scheme. You can also.

  According to such a configuration, the operating current control means can control the operating current of the VCO so that the C / N is optimized according to the transmission state, so that the consumption in a state where the C / N requirement is low. The current can be reduced. Further, since the operating current control means performs control so as to achieve an optimum C / N according to each modulation method, as a result, the power consumption of the VCO can be reduced.

  According to the transmission apparatus of the present invention, the operating current control unit that controls the operating current of the VCO according to the transmission state information is provided, and the operating current of the VCO is controlled according to the transmission power, so that the C / N requested by the VCO When the power is low and the output is low, it is possible to suppress excessive current consumption in the VCO, and it is possible to extend the talk time by suppressing battery consumption. Further, according to the transmission apparatus of the present invention, the operating current control means controls the operating current of the VCO according to the transmission frequency. This makes it possible to suppress excessive current consumption in the VCO at the time of transmission frequency setting with a large frequency difference from the reception band, and as a result, it is possible to extend the call time.

  In addition, according to the transmission apparatus of the present invention, the operating current control unit that controls the operating current of the VCO according to the transmission state information is provided, and the operating current of the VCO is controlled according to the band of the transmission frequency. This makes it possible to suppress excessive current consumption in the VCO during “Lo-Band” transmission in which the frequency division ratio is high and the C / N after frequency division is improved, resulting in longer call time. be able to. Further, according to the transmission apparatus of the present invention, the operating current control means controls the operating current of the VCO according to the modulation method, thereby suppressing excessive current consumption in the VCO in the modulation method with a low C / N requirement. As a result, the call time can be increased.

<Summary of invention>
The transmitter of the present invention compares the oscillation signal of the VCO with a reference signal, modulates the output signal of the PLL that controls the oscillation frequency of the VCO to a desired frequency by the modulation circuit, and transmits the modulation signal. The operating current flowing through the VCO is controlled in accordance with the transmission state of the modulation signal transmitted from. The transmission state is transmission power, transmission frequency, transmission frequency band, or the like. As a result, the power consumption of the VCO can be reduced, so that the battery life can be extended, and as a result, the call time can be extended.

<Embodiment>
Hereinafter, an embodiment of a transmission apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a transmission apparatus using a VCO according to an embodiment of the present invention. The transmission apparatus shown in FIG. 1 compares the VCO 109 oscillating at a predetermined frequency, the reference oscillator 113 that outputs the reference signal 115S, and the oscillation signal 118S of the VCO 109 and the reference signal 115S in accordance with the frequency setting signal 114S. The PLL 112 that controls the oscillation frequency of the VCO 9 to the set frequency, the operating current control unit 111 that controls the operating current flowing through the VCO 109 according to the input transmission state information 117S, the frequency setting signal 114S and the transmission state information 117S are sent out. Control unit 110, frequency dividers 105 to 108 for dividing the oscillation signal 118S output from the VCO 109, and receiving the frequency-divided oscillation signal to convert the modulation signal 116S to a desired frequency and outputting a transmission signal The modulation circuits 101 to 104 are configured.

  Next, the operation of the transmission apparatus shown in FIG. 1 will be described. The frequency setting signal 114S is calculated by the control unit 110 and input to the PLL 112 in accordance with a preset transmission frequency. Then, the PLL 112 compares the reference signal 115S with the oscillation signal 118S output from the VCO 109, and controls the oscillation frequency of the VCO 109 so that the frequency specified by the frequency setting signal 114S is obtained. The oscillation signal 118S output from the VCO 109 is divided by the frequency dividers 105 to 108 and input to the modulation circuits 101 to 104.

  The modulation circuits 101 to 104 receive the oscillation signals output from the frequency dividers 105 to 108, convert the modulation signal 116S into a desired frequency, and output it as a transmission signal. For example, the modulation circuit 101 outputs a “System 1” “Hi-Band” transmission signal, and the modulation circuit 102 outputs a “System 1” “Lo-Band” transmission signal. Similarly, the modulation circuit 103 outputs a “System 2” “Hi-Band” transmission signal, and the modulation circuit 104 outputs a “System2” “Lo-Band” transmission signal.

  At this time, the operating current control unit 111 controls the operating current of the VCO 109 based on the transmission state information 117S from the control unit 110 so that the C / N of the transmission signal is optimized. Note that the transmission state information 117S output from the control unit 110 is transmission power, transmission frequency, transmission frequency band, or the like.

  As shown in FIG. 1, when a plurality of modulation schemes are realized by a plurality of modulation circuits 101 to 104 using a single VCO 109, the operating current control unit 111 includes the modulation circuits 101 to 104. The operating current flowing through the VCO 109 can be controlled according to the modulation method.

  According to the transmission apparatus of the present embodiment, VCO 109 corresponds to transmission state information 117S output corresponding to the transmission state of the transmission signal (that is, transmission power, transmission frequency, transmission frequency band, or modulation scheme). By providing the operating current control unit 111 that controls the operating current, it is possible to reduce the current consumption in the transmission state where high C / N is not required, and as a result, it suppresses battery consumption and extends the talk time. be able to.

  Since the transmission device according to the present invention controls the operating current so as to achieve an optimum C / N with a simple circuit configuration, it is effective for a versatile mobile phone or the like that extends the battery life. Can be used.

The block diagram which shows the structure of the transmitter using VCO which concerns on one embodiment of this invention Block diagram showing the configuration of a conventional transmission apparatus using a VCO Spectrum characteristics of VCO by operating current The figure which shows the specification of the modulation spectrum in GSM

Explanation of symbols

101-104 Modulation circuit 105-108 Frequency divider 109 VCO
110 Control Unit 111 Operating Current Control Unit 112 PLL
113 Reference oscillator

Claims (5)

A PLL that compares the oscillation signal of the VCO with a reference signal in accordance with a frequency setting signal, controls the oscillation frequency of the VCO to a set frequency, and a modulation circuit that modulates the output signal of the PLL and transmits the modulation signal A transmission device comprising:
A transmission apparatus comprising: an operating current control unit configured to control an operating current flowing through the VCO according to a transmission state of a modulation signal transmitted from the modulation circuit.   The transmission apparatus according to claim 1, wherein a transmission state of a modulation signal transmitted from the modulation circuit is transmission power.   The transmission apparatus according to claim 1, wherein a transmission state of a modulation signal transmitted from the modulation circuit is a transmission frequency.   The transmission apparatus according to claim 1, wherein a transmission state of a modulation signal transmitted from the modulation circuit is a band of a transmission frequency. A PLL that compares the oscillation signal of the VCO with a reference signal in accordance with a frequency setting signal, controls the oscillation frequency of the VCO to a set frequency, and a modulation circuit that modulates the output signal of the PLL and transmits the modulation signal And a transmitter that realizes a plurality of modulation schemes by sharing the VCO,
A transmission apparatus comprising operating current control means for controlling an operating current flowing through the VCO in accordance with the modulation method.

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