JP2008199163A - Quadrature carrier generator, radio transmitter and radio receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quadrature carrier generator capable of suppressing the variations of modulation and demodulation characteristics in the view from baseband signals caused by various factors including the variations of temperature characteristics and frequency characteristics and suitable for further power saving, and a radio transmitter and a radio receiver utilizing it. <P>SOLUTION: The quadrature carrier generator includes: a phase shifter configured to generate two carrier waveforms perpendicular to each other from input oscillation waveforms and control the amplitude values of the two carrier signals by control signals; an amplitude detector for outputting a detection voltage equivalent to the amplitude value of at least one of the two carrier waveforms; and a comparator/amplifier for supplying output signals obtained by amplifying a difference between the detection voltage and a reference voltage to the phase shifter as the control signals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an orthogonal carrier generation device that generates orthogonal carriers necessary for performing orthogonal modulation / demodulation, and a wireless transmitter and a wireless receiver using the orthogonal carrier generation device.

  For example, in a wireless transceiver such as a cellular phone, a baseband two-phase signal is modulated by a two-phase carrier (I [in-phase] carrier, Q [quadrature] carrier) orthogonal to each other on the transmission side for transmission and emission. The modulated signal (the combined signal of the I signal and the Q signal) is obtained, and the receiving side, on the contrary, demodulates the modulated signal captured by the antenna with the orthogonal two-phase carrier to generate the baseband two-phase signal. The process to get is done.

  Two-phase carriers generally require equiamplitude and an accurate 90 degree phase difference. If these are not ensured, the communication quality deteriorates, for example, the I signal and the Q signal are mixed and an image signal is generated. Further, even if the equal amplitude is ensured, if the absolute value varies, the modulation / demodulation characteristics of the products as viewed from the baseband signal will vary. In the “Quadrature modulator integrated circuit” disclosed in Patent Document 1 below, an amplitude limiter is provided on the output side of the phase shifter to ensure equal amplitude of the two-phase carrier. The “90-degree phase shifter” disclosed in Patent Document 2 below provides a feedback path that detects a phase difference from 90 degrees of a two-phase carrier and feeds it back to the RC phase shifter, so as to increase the bandwidth as the phase shifter. ing.

In these examples, in order to obtain an equiamplitude property and an accurate phase difference of 90 degrees, it is necessary to limit a waveform that has been sufficiently amplified, or to detect a phase difference with a waveform having a sufficient amplitude. For these reasons, it is difficult to further reduce power consumption required for integrated circuits. In these examples, there is a problem that modulation / demodulation characteristics vary due to variations in temperature characteristics and frequency characteristics.
Japanese Patent Laid-Open No. 9-214577 Japanese Patent Laid-Open No. 8-18397

  The present invention is capable of suppressing variations in modulation / demodulation characteristics as seen from a baseband signal caused by various factors including variations in temperature characteristics and frequency characteristics, and uses an orthogonal carrier generator for further power saving, and using the same An object of the present invention is to provide a wireless transmitter and a wireless receiver.

  An orthogonal carrier generation device that is one embodiment of the present invention generates two carrier waveforms that are orthogonal to each other from an input oscillation waveform, and is configured to be capable of controlling the amplitude values of the two carrier signals by a control signal. An phase detector, an amplitude detector that outputs a detection voltage corresponding to an amplitude value of at least one of the two carrier waveforms, and an output signal obtained by amplifying a difference between the detection voltage and a reference voltage Is supplied to the phase shifter as the control signal.

  In this orthogonal carrier generation device, a phase shifter that is configured so that both amplitude values of two carrier signals can be controlled by an external signal is used. Regarding the equal amplitude property of two carriers and an accurate 90-degree phase difference, for example, a configuration in which an oscillation waveform oscillated at a double frequency is input to a predetermined flip-flop circuit is used. The two carriers can be generated. As such, power consumption is not limited to limiting a waveform that has undergone sufficient amplification or detecting a phase difference with a waveform having sufficient amplitude. Furthermore, it has a carrier waveform amplitude detector and a comparator / amplifier that supplies an output voltage equivalent to an error from the reference voltage of the detected amplitude value to the phase shifter, thereby controlling the amplitude of the carrier waveform to a constant level. Is done. Therefore, by using this orthogonal carrier generation device, it is possible to suppress variations in modulation / demodulation characteristics as seen from the baseband signal in the orthogonal modulator / demodulator.

  In addition, a radio transmitter according to another aspect of the present invention includes a baseband signal processing unit that generates a two-phase baseband signal, an oscillation waveform input, and two carrier waveforms that are orthogonal to each other. A phase shifter configured such that both of the amplitude values of one carrier signal can be controlled by a control signal, and at least one of the two carrier waveforms is input, and detection corresponding to the amplitude value of the at least one carrier waveform A quadrature carrier generation apparatus comprising: an amplitude detector that outputs a voltage; and a comparison / amplifier that supplies an output signal obtained by amplifying the detected voltage by comparing with a reference voltage to the phase shifter as the control signal; A quadrature modulator that quadrature modulates the two carrier signals with the two-phase baseband signal to generate a modulated signal, and power that amplifies the modulated signal to generate a power amplified signal It includes a width unit, and an antenna for radio emission of the power amplified signal.

  A radio receiver according to still another aspect of the present invention includes an antenna that captures radio waves and outputs an RF signal, an oscillation waveform is input, and two carrier waveforms that are orthogonal to each other are generated. A phase shifter configured to be capable of controlling both of the amplitude values by a control signal and at least one of the two carrier waveforms is input, and a detection voltage corresponding to the amplitude value of the at least one carrier waveform is output. A quadrature carrier generation apparatus comprising: an amplitude detector that compares the detected voltage with a reference voltage; and a comparison / amplifier that supplies an output signal obtained by amplifying the detected voltage to the phase shifter as the control signal; A quadrature demodulator for demodulating a signal with the two carrier signals to generate a two-phase baseband signal; and a baseband signal processing unit for processing the two-phase baseband signal. That.

  These wireless transmitter and wireless receiver are a wireless transmitter and a wireless receiver, respectively, using the orthogonal carrier generation device.

  According to the present invention, in an orthogonal carrier generation device, and a radio transmitter and radio receiver using the orthogonal carrier generation device, it is possible to suppress variation in modulation / demodulation characteristics as seen from a baseband signal and to further reduce power consumption. it can.

  As an embodiment in the above aspect, the phase shifter includes a bias current source, and the amplitude values of the two carrier waveforms vary depending on a current generated by the bias current source, and the bias The output signal of the comparison / amplifier is supplied to the current source as the control signal, and the current of the bias current source is controlled by the output signal. This is a configuration in which feedback is made to a bias current source included in the phase shifter and amplitude values of two carrier waveforms are controlled as desired.

  Further, as an embodiment, the phase shifter includes an input node to which a bias voltage is applied and the oscillation waveform is transferred, and a bias voltage source that generates the bias voltage. The amplitude values of the two carrier signals vary, the output signal of the comparison / amplifier is supplied to the bias voltage source as the control signal, and the bias voltage is controlled by the output signal. be able to. This is a configuration in which the phase shifter has feedback to a bias voltage source for applying a bias voltage to the input signal, and the amplitude values of the two carrier waveforms are controlled as desired.

  Further, as an embodiment, it may further include a reference voltage source that generates the reference voltage, and the reference voltage source may be configured to be able to control the value of the reference voltage with an external signal. . According to this, it is possible to set the amplitude of the carrier waveform to be controlled from the outside. The amplitude of the carrier waveform is controlled according to the set amplitude.

  As an embodiment, the phase shifter includes a first buffer circuit that outputs one of the two carrier waveforms and a second buffer circuit that outputs the other, and the first and second buffer circuits. The amplitude value of each output can be controlled by the control signal. With such a configuration, there is a possibility that the amplitude values of two carrier waveforms can be controlled individually (that is, with higher accuracy).

  Here, each of the first and second buffer circuits of the phase shifter is such that the amplitude value of the output varies depending on a current generated by a bias current source included in each of the first and second buffer circuits. The output signal of the comparison / amplifier is supplied as the control signal, and the current of each of the bias current sources is controlled by the output signal. In this configuration, the bias current sources of the two buffer circuits that individually output the two carrier waveforms are used as a configuration for individually controlling the amplitude values of the two carrier waveforms.

  Alternatively, here, the amplitude detector receives one of the two carrier waveforms and outputs a first detection voltage corresponding to the amplitude value of the one carrier waveform, and the 2 A second sub-detector that receives the other of the two carrier waveforms and outputs a second detection voltage corresponding to the amplitude value of the other carrier waveform, and the comparison / amplifier includes the first detection voltage. A first sub-amplifier supplying the phase shifter with a first output voltage obtained by amplifying the reference voltage as a control signal, and comparing the second detection voltage with the reference voltage. A second sub-amplifier that supplies the amplified second output voltage to the phase shifter as another control signal, and the first output signal has an amplitude value of the one carrier waveform. The second output signal is controlled by the other key. Controlling the amplitude value of the rear waveform can be.

  This is a configuration in which the amplitudes of two carrier waveforms are controlled by individual feedback. According to this, even when a slight amplitude difference can occur between the two carrier waveforms in the phase shifter, this can be suppressed.

  Alternatively, here, the first buffer circuit of the phase shifter has a first bias current source, and the amplitude value of the output varies depending on a current generated by the first bias current source. And the second buffer circuit of the phase shifter has a second bias current source, and the amplitude value of the output varies depending on the current generated by the second bias current source. And the amplitude detector receives the one of the two carrier waveforms and outputs a first detection voltage corresponding to the amplitude value of the one carrier waveform, and the two A second sub-detector that receives the other of the carrier waveforms and outputs a second detection voltage corresponding to the amplitude value of the other carrier waveform, and the comparison / amplifier includes the first detection voltage. And the first voltage obtained by amplifying the difference between the reference voltage and the reference voltage. A first sub-amplifier for supplying a force voltage to the phase shifter as one of the control signals, and a second output voltage obtained by amplifying a difference between the second detection voltage and the reference voltage as the control signal. A second sub-amplifier for supplying to the phase shifter, wherein the first output voltage is supplied to the first bias current source of the first buffer circuit, and the first bias voltage is supplied to the first bias current source of the first buffer circuit. The current of the current source is controlled by the first output signal, the second output voltage is supplied to the second bias current source of the second buffer circuit, and the current of the second bias current source Can be controlled by the second output signal.

  In this configuration, the bias current sources of the two buffer circuits that individually output the two carrier waveforms are used as a configuration for individually controlling the amplitude values of the two carrier waveforms. In addition, the amplitudes of the two carrier waveforms are controlled by individual feedback. According to this, even when a slight amplitude difference can occur between the two carrier waveforms in the phase shifter, this can be suppressed.

  Based on the above, embodiments will be described below with reference to the drawings. FIG. 1 shows a configuration of an orthogonal carrier generation device according to an embodiment. As shown in FIG. 1, the orthogonal carrier generation device includes a phase shifter 11, an amplitude detector 12, a filter 13, a reference voltage source 14, and a comparison / amplifier 15. The two-phase carrier waveform that is the output of the quadrature carrier generation device is supplied to the quadrature modulator 21 as a two-phase (I, Q) carrier waveform.

  An oscillating waveform having a predetermined frequency is input to the phase shifter 11, and this waveform is internally manipulated to generate two-phase carriers having substantially equal amplitudes that are orthogonal to each other. The amplitude of the two-phase carrier waveform generated and output can be controlled by the voltage guided to the amplitude control input terminal 11a. The two-phase carrier waveform is supplied to the quadrature modulator 21 and the amplitude detector 12. That is, FIG. 1 shows an example in which this orthogonal carrier generation device is applied to an orthogonal modulator.

  The amplitude detector 12 detects the amplitude of the two-phase carrier waveform by, for example, full-wave rectification or half-wave rectification of the supplied two-phase carrier waveform. In the figure, both of the two-phase carrier waveforms are input to the amplitude detector 12, but there may be a configuration in which only one of them is input. The filter 13 filters the fluctuation component remaining at the output of the amplitude detector 12 and supplies the amplitude detection voltage with the fluctuation component suppressed as one input of the comparison / amplifier 15.

  The reference voltage source 14 is a voltage source of a voltage at which the amplitude detection voltage at the output of the filter 13 is to be set. The voltage source 14 is configured so that the output voltage does not fluctuate due to process variations, temperature fluctuations, power supply voltage fluctuations, and the like when integrated circuits are used. This voltage can be controlled by a control input input to the voltage control input terminal 14a. The voltage output from the reference voltage source 14 is supplied as the other input of the comparison / amplifier 15. The comparison / amplifier 15 compares an output signal obtained by amplifying the supplied amplitude detection voltage with a large gain by comparing the voltage output from the reference voltage source 14 with a reference to the amplitude control input terminal 11 a of the phase shifter 11. Lead.

  The quadrature modulator 21 modulates and synthesizes the input two-phase carrier waveform with each two-phase baseband signal and outputs a modulated signal.

  In the quadrature carrier generation device shown in FIG. 1, the amplitude of the two-phase carrier signal output from the phase shifter 11 is controlled according to the voltage output from the reference voltage source 14. Here, the equiamplitude property and accurate 90-degree phase difference between the two carrier waveforms can be secured as the properties of the phase shifter 11 itself (details will be described later). Therefore, it is possible to save power by limiting the waveform that has undergone sufficient amplification in order to ensure these and detecting the phase difference with a waveform having sufficient amplitude. In addition, the amplitude of the two-phase carrier waveform is controlled to a certain level with high accuracy regardless of process variations, temperature fluctuations, power supply voltage fluctuations, etc. Can be suppressed.

  FIG. 2 shows the configuration of the orthogonal carrier generation apparatus shown in FIG. 1 in more detail. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 2, the signal supplied to the amplitude control input terminal 11a specifically controls the current value of the bias current source 11b provided in the phase shifter 11, for example. In the phase shifter 11, the amplitude value of the output two-phase carrier waveform varies depending on the current of the bias current source 11b.

  FIG. 3 shows a specific example of the phase shifter 11 shown in FIGS. In FIG. 3, the same reference numerals are given to the same components as those already shown in the drawings.

  The phase shifter 11 includes a flip-flop configured by combining MOS transistors. The outline of the operation is as follows. The MOS transistors M1 and M2 convert the oscillation waveforms (voltages) input in a differential manner into currents and use them as drain currents. The same applies to the MOS transistors M3 and M4. MOS transistors M7 and M8 constitute a latch among the flip-flops, and MOS transistors M5 and M6 constitute a slave among the flip-flops. These latches and slaves divide the drain currents of the MOS transistors M1 and M2 by a factor of 1/2, and generate a voltage signal that fluctuates at the lower ends of the load resistors R1 and R2. This signal becomes one of the carrier waveforms (here, obtained as a differential output).

  MOS transistors M11 and M12 also constitute a latch, and MOS transistors M9 and M10 constitute a slave. These latches and slaves divide the drain currents of the MOS transistors M3 and M4 by ½ in frequency, and generate a voltage signal that fluctuates at the lower ends of the load resistors R3 and R4. This signal becomes the other carrier waveform (also obtained as a differential output).

  Here, one carrier waveform output controls the gates of the transistors M9 and M10 which are slaves on the side that generates the other carrier waveform, and the other carrier waveform output is a slave on the side that generates one carrier. The gates of the transistors M5 and M6 are controlled. By such mutual connection, the operation is performed so that the phase difference between the two-phase carrier waveforms as outputs is 90 degrees with high accuracy. The operation as a flip-flop is performed by switching of a latch or slave transistor, and the amplitude of each carrier waveform is determined according to the bias current of the flip-flop.

  That is, the amplitude of the output carrier waveform is such that the resistor R5 (or a current source corresponding to this instead of the resistor) that determines the bias current of the flip-flop, the MOS transistor M13, and the resistor R6 (or resistor). And a current source corresponding to this) and the MOS transistor M14. This is because the current flowing through them also flows through the load resistors R1 to R4. The MOS transistors M13 and M14 correspond to the bias current source 11b shown in FIG. 2, and their gates are connected from the amplitude control input terminal 11a.

  Note that the bias voltage source 11c has an output connected to an input node to which an oscillation waveform is passed, and thereby has a function of applying a predetermined bias voltage to the input node.

  Since the phase shifter 11 described above is composed of flip-flops that combine MOS transistors, in principle, the phase relationship between the two carrier waveforms and their equiamplitude are very high. Since the phase does not depend on analog elements, these features have many advantages such as being unaffected by the frequency of the input oscillation waveform. In the case of circuit integration, a micro-processed MOS transistor is used, and a low operating voltage (for example, Vdd = 1.5V) and a low operating current (typical current value per one of MOS transistors M1, M2, M3, and M4). For example, 200 μA) can be realized, and power saving can be achieved.

  FIG. 4 shows the output amplitude of the two-phase carrier waveform with respect to the amplitude control input voltage in the phase shifter 11 shown in FIG. Thus, the output amplitude of the two-phase carrier waveform exhibits a monotonically increasing characteristic with respect to the amplitude control input voltage. The amplitude control input voltage is, for example, 0 to 1.5 V, and the output amplitude of the two-phase carrier waveform is, for example, 200 mV (zero peak) to 800 mV (zero peak) (typically, for example, 400 mV (zero peak)).

  FIG. 5 shows a specific example of the amplitude detector 12 and the filter 13 shown in FIGS. FIGS. 5A, 5B, and 5C are examples.

  The example shown in FIG. 5A has a configuration in which both differential phases are input for two-phase carrier waveforms I and Q (that is, full-wave rectification). Respective inputs are supplied to source followers by MOS transistors M21 to M24 and current sources I21 and I22, and their outputs are synthesized by resistors R21 and R22. Further, it is guided to the filter 13 by the resistor R23 and the capacitor C21 and is low-pass filtered to become a detection voltage.

  The example shown in FIG. 5B has a configuration in which both differential phases of only one of the two-phase carrier waveforms I and Q are input (that is, full-wave rectification) (amplitude detector 12A). Both differential inputs are supplied to the source follower by the MOS transistors M21 and M22 and the current source I21, and the output is low-pass filtered by the filter 13A by the capacitor C21 to become a detection voltage. In the example shown in FIG. 5C, a filter 13 including a resistor 23 and a capacitor 23 is used in place of the filter 13A in FIG.

  The two-phase carrier waveforms I and Q are not full-wave rectified but half-wave rectified (that is, only one of the transistors M21 and M22 and only one of the transistors M23 and M24 is provided). Good. However, the full-wave rectification is larger than the half-wave rectification, and the effective value of the detection voltage is larger, and as a result, the detection accuracy is higher. This is because the two-phase carrier waveform input (FIG. 5A) is also compared with the case where only one carrier waveform is input (FIGS. 5B and 5C). It is the same.

  FIG. 6 shows the detection voltage with respect to the input amplitude of the two-phase carrier waveform in the amplitude detector 12 and the filter 13 (or 13A) shown in FIG. Thus, the detected voltage exhibits a monotonically increasing characteristic with respect to the input amplitude of the two-phase carrier waveform. The amplitude of the two-phase carrier waveform is typically 400 mV (zero peak), for example, and the detection voltage is typically 400 mV, for example. The inclination can be set to about 0.5 [−].

  Next, FIG. 7 shows a configuration of an orthogonal carrier generation device according to another embodiment. In FIG. 7, the same components as those already shown in the description are given the same reference numerals, and the description thereof is omitted. As shown in the figure, in this embodiment, the signal supplied to the amplitude control input terminal 11a specifically controls the voltage of the bias voltage source 11ca provided in the phase shifter 11A. . In the phase shifter 11A, the amplitude value of the output two-phase carrier waveform varies depending on the voltage of the bias voltage source 11ca.

  FIG. 8 shows a specific example of the phase shifter 11A shown in FIG. In FIG. 8, the same reference numerals are given to the same or equivalent components as those already shown in the drawings. The description is omitted.

  In this phase shifter 11A, the bias voltage source 11ca shown in FIG. 7 is a bias voltage source connected to the input node to which the oscillation waveform is transferred. The voltage output from the bias voltage source 11ca varies depending on the voltage value input to the amplitude control input terminal 11a, and thereby the gate-source voltages of the transistors M1 to M4 vary. That is, when the voltage output from the bias voltage source 11ca increases (decreases), the gate-source voltages of the transistors M1 to M4 increase (decrease), thereby increasing (decreasing) the average drain current of the transistors M1 to M4. Thus, the voltage fluctuation (amplitude) generated at the lower ends of the load resistors R1 to R4 increases (decreases).

  Similarly to the phase shifter 11 shown in FIG. 3, this phase shifter 11A is also composed of a flip-flop that combines MOS transistors. Therefore, in principle, the accuracy of the phase relationship between the two carrier waveforms and their phase Since the equiamplitude is very high and the phase shift does not depend on the analog element, there are many advantages such that these features are not affected by the frequency of the input oscillation waveform. In the case of circuit integration, a micro-processed MOS transistor is used, and a low operating voltage (for example, Vdd = 1.5V) and a low operating current (typical current value per one of MOS transistors M1, M2, M3, and M4). For example, 200 μA) can be realized, and power saving can be achieved.

  Next, FIG. 9 shows a configuration of an orthogonal carrier generation device according to still another embodiment. In FIG. 9, the same components as those already shown in the drawings described above are denoted by the same reference numerals, and the description thereof is omitted. As shown in the figure, in this embodiment, the signal supplied to the amplitude control input terminal 11a specifically controls the two-phase carrier output buffers 11d and 11e provided in the phase shifter 11B. It has become. In the phase shifter 11B, the amplitude value of the two-phase carrier waveform output by this control varies.

  FIG. 10 shows a specific example of the phase shifter 11B shown in FIG. In FIG. 10, the same reference numerals are given to the same or equivalent components as those already shown in the drawings. The description is omitted.

  In this phase shifter 11B, the buffers 11d and 11e shown in FIG. 9 are respectively configured by source followers by MOS transistors M81 to M84 and current sources I1 to I4. The current of the follower is set. Here, the current values of the current sources I1 to I4 are controlled by the voltage supplied to the amplitude control input terminal 11a. Each of the buffers 11d and 11e has two source followers for outputting a differential carrier waveform.

  When these currents are controlled by each source follower, the voltage gain of the transistors M81 to M84 constituting them changes (when the current is increased, the voltage gain of the source follower approaches 1), and as a result, its output This is a change in the voltage change width of the signal (ie, a change in amplitude). Thereby, the amplitude of the two-phase carrier waveform can be controlled.

  In the same way as the phase shifters 11 and 11A shown in FIGS. 3 and 8, this phase shifter 11B is also very high in the accuracy of the phase relationship between the two carrier waveforms and their equal amplitude. Furthermore, since the phase shift is not based on analog elements, there are many advantages such that these features are not affected by the frequency of the input oscillation waveform. In the case of circuit integration, a micro-processed MOS transistor is used, and a low operating voltage (for example, Vdd = 1.5V) and a low operating current (typical current value per one of MOS transistors M1, M2, M3, and M4). For example, 200 μA) can be realized, and although there is an increase in current required by the current sources I1 to I4, power saving is still realized.

  Furthermore, since the buffers 11d and 11e are provided individually corresponding to each of the two-phase carriers, it is possible to open the way to a configuration for individually controlling the amplitude of the two-phase carriers as an advanced application. .

  FIG. 11 is an example of a configuration for individually controlling the amplitude of such a two-phase carrier, and shows a configuration of an orthogonal carrier generation device according to another (fourth) embodiment. In FIG. 11, the same reference numerals are given to the same or equivalent components as those already shown in the drawings. The description is omitted.

  In this embodiment, feedback for controlling the amplitude is provided for one and the other of the two-phase carriers, respectively. That is, the carrier waveform on one side (I) is used for feedback to the buffer 11d on one side through the amplitude detector 12A, the filter 13 and the comparison / amplifier 15 on the upper side in the figure. The carrier waveform on the other side (Q) is used for feedback to the buffer 11e on the other side through the amplitude detector 12A, the filter 13, and the comparison / amplifier 15 on the lower side in the figure.

  According to such a configuration, even if there is a deviation in the output amplitude of the two-phase carrier in the phase shifter 11B, this deviation is removed and the equiamplitude between the two-phase carrier waveforms is higher. An orthogonal carrier generation device can be obtained.

  FIG. 12 shows a specific example of the phase shifter 11B shown in FIG. In FIG. 12, the same reference numerals are given to the same or equivalent components as those already shown in the drawings. The description is omitted.

  This phase shifter 11B has substantially the same configuration as that shown in FIG. The difference is that two amplitude control input terminals 11a are provided, and voltages supplied to them can be individually guided to the buffers 11d and 11e. The functions and operations of the buffers 11d and 11e are as already described.

  The case where the orthogonal carrier generation device according to each embodiment is applied to the orthogonal modulator 21 has been described above. Of course, the orthogonal carrier generation apparatus of each embodiment can be applied to an orthogonal demodulator in the same manner. FIG. 13 shows a configuration when the orthogonal carrier generation device according to one embodiment is used in a demodulator. In FIG. 13, the same reference numerals are given to the components that have already appeared in the already described diagram. The description is omitted.

  In FIG. 13, the functions and operations of the phase shifter 11, the amplitude detector 12, the filter 13, the reference voltage source 14, and the comparison / amplifier 15 constituting the quadrature carrier generation device are the same as those described in FIG. . The two-phase carrier waveform generated by these is input to the quadrature demodulator 22, and the RF signal corresponding to the modulated signal described in FIG. 1 is demodulated by two orthogonal axes. The demodulated result is obtained as a demodulated two-phase baseband signal. The two-phase carrier waveform input to the quadrature demodulator 22 can be the one generated by each of the above embodiments instead of the one shown in FIG.

  Next, a case where the orthogonal carrier generation apparatus described above is applied to a radio transmitter and a radio receiver such as a mobile phone will be described with reference to FIG. FIG. 14 shows a configuration of a wireless transmitter and a wireless receiver (combined machine) according to an embodiment. The same reference numerals are given to the same components as those already shown in the drawings. In this example, a TTD (time division duplex) system in which transmission / reception switching is performed in a time division manner is shown, but the embodiment is not limited thereto.

  As shown in FIG. 14, this dual-purpose machine includes an orthogonal carrier generation device 51, a baseband signal processing unit (for transmission) 52, an orthogonal modulator 21, a variable gain amplifier 53, a power amplifier 54, a transmission / reception switch 55, an antenna 56, A band-pass filter 61, a low-noise amplifier 62, a band-pass filter 63, an orthogonal demodulator 22, an orthogonal carrier generation device 64, and a baseband signal processing unit (for reception) 65 are included. As the orthogonal carrier generation devices 51 and 64, the orthogonal carrier generation device according to each embodiment described above can be used.

  The operation of this dual-purpose machine will be described together with the functions of the components. First, at the time of transmission, the baseband signal processing unit 52 performs each process to generate a transmission signal in the baseband. A predetermined band limitation is performed at the end of the process. The baseband signals thus obtained are composed of two phases, and these are guided to the quadrature modulator 21 to modulate the two-phase carrier signals from the quadrature carrier generation device 51, respectively. Simultaneously with the modulation, they are combined and supplied to the variable gain amplifier 53 as a modulated signal.

  The variable gain amplifier 53 is controlled to have an appropriate gain by a control signal from a control system (not shown), and the modulated signal is amplified with the controlled gain. The amplified modulated signal is supplied to the power amplifier 54. In the power amplifier 54, power amplification for radiating the modulated signal from the antenna 56 is performed. The modulated signal subjected to power amplification is supplied to the antenna 56 in a state where the transmission / reception switch 55 is switched to the transmission side of transmission / reception. The modulated signal supplied to the antenna 56 is radiated as a radio wave.

  Next, at the time of reception, a signal radiated in the air as a radio wave is captured by the antenna 56 and guided to the band pass filter 61 as an RF signal in a state where the transmission / reception switch 55 is switched to the receiving side. The bandpass filter 61 removes unnecessary frequency components, and the output thereof is amplified by the low noise amplifier 62 with low noise characteristics. The low noise amplified FR signal is guided to the band pass filter 63 to remove unnecessary frequency components, and the output RF signal is input to the quadrature demodulator 22.

  The quadrature demodulator 22 demodulates the input RF signal using two orthogonal axes using the two-phase carrier waveform from the quadrature carrier generator 64. The demodulated two-phase baseband signal obtained by the demodulation is guided to a baseband signal processing unit (for reception) 65, and the baseband signal processing unit 65 performs predetermined baseband processing for reproducing the transmitted information. Is made.

  In the wireless transmitter and the wireless receiver of this embodiment, since the orthogonal carrier generation devices 51 and 64 of the embodiment already described are used, variations in modulation / demodulation characteristics viewed from the baseband signal can be suppressed and further. Power saving is achieved.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram which shows the structure of the orthogonal carrier generation apparatus which concerns on one Embodiment. The block diagram which shows the structure of the orthogonal carrier production | generation apparatus shown in FIG. 1 in detail. FIG. 3 is a circuit diagram showing a specific example of the phase shifter shown in FIGS. 1 and 2. FIG. 4 is a characteristic diagram showing an output amplitude of a two-phase carrier waveform with respect to an amplitude control input voltage in the phase shifter shown in FIG. 3. FIG. 3 is a circuit diagram showing a specific example of an amplitude detector and a filter shown in FIGS. 1 and 2. FIG. 6 is a characteristic diagram showing a detection voltage with respect to an input amplitude of a two-phase carrier waveform in the amplitude detector and filter shown in FIG. 5. The block diagram which shows the structure of the orthogonal carrier generation apparatus which concerns on another embodiment. FIG. 8 is a circuit diagram showing a specific example of the phase shifter shown in FIG. 7. The block diagram which shows the structure of the orthogonal carrier generation apparatus which concerns on another embodiment. FIG. 10 is a circuit diagram showing a specific example of the phase shifter shown in FIG. 9. The block diagram which shows the structure of the orthogonal carrier generation apparatus which concerns on another (4th) embodiment. The circuit diagram which shows the specific example of the phase shifter shown in FIG. The block diagram which shows the structure in the case of using the orthogonal carrier generation apparatus which concerns on one Embodiment for a demodulator. The block diagram which shows the structure of the radio | wireless transmitter and radio | wireless receiver which concern on one Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11, 11A, 11B ... Phase shifter, 11a ... Amplitude control input terminal, 11b ... Bias current source, 11c ... Bias voltage source, 11ca ... Bias voltage source, 11d, 11e ... Buffer, 12, 12A ... Amplitude detector, 13 , 13A ... filter, 14 ... reference voltage source, 14a ... voltage control input terminal, 15 ... comparison / amplifier, 21 ... quadrature modulator, 22 ... quadrature demodulator, 50 ... oscillator, 51 ... quadrature carrier generator, 52 ... base Band signal processing unit (transmission), 53 ... variable gain amplifier, 54 ... power amplifier, 55 ... transmission / reception switch, 56 ... antenna, 61 ... bandpass filter, 62 ... low noise amplifier, 63 ... bandpass filter, 64 ... orthogonal carrier Generation device, 65... Baseband signal processing unit (reception).

Claims (9)

A phase shifter configured to generate two carrier waveforms orthogonal to each other from an input oscillation waveform and to control the amplitude values of the two carrier signals by a control signal;
An amplitude detector that outputs a detection voltage corresponding to an amplitude value of at least one of the two carrier waveforms;
A quadrature carrier generation apparatus comprising: a comparison / amplifier that supplies an output signal obtained by amplifying a difference between the detection voltage and a reference voltage to the phase shifter as the control signal. The phase shifter has a bias current source, and the amplitude values of the two carrier waveforms vary depending on a current generated by the bias current source.
The orthogonal carrier generation device according to claim 1, wherein the output signal of the comparison / amplifier is supplied to the bias current source as the control signal, and the current of the bias current source is controlled by the output signal. . The phase shifter has an input node to which a bias voltage is applied and the oscillation waveform is transferred, and a bias voltage source that generates the bias voltage, and the amplitude of the two carrier signals depends on the bias voltage The value fluctuates,
The quadrature carrier generation device according to claim 1, wherein the output signal of the comparison / amplifier is supplied to the bias voltage source as the control signal, and the bias voltage is controlled by the output signal.   The phase shifter includes a first buffer circuit that outputs one of the two carrier waveforms and a second buffer circuit that outputs the other, and amplitude values of outputs of the first and second buffer circuits, respectively. The orthogonal carrier generation device according to claim 1, wherein the orthogonal carrier generation device is controlled by the control signal. The first and second buffer circuits of the phase shifter vary the amplitude value of the output depending on a current generated by a bias current source included in each of the first and second buffer circuits.
The orthogonal carrier according to claim 4, wherein the output signal of the comparison / amplifier is supplied as the control signal to each of the bias current sources, and the current of each of the bias current sources is controlled by the output signal. Generator. The amplitude detector receives one of the two carrier waveforms, outputs a first detection voltage corresponding to the amplitude value of the one carrier waveform, and the other of the two carrier waveforms And a second sub-detector for outputting a second detection voltage corresponding to the amplitude value of the other carrier waveform,
A first sub-amplifier for supplying a first output voltage obtained by comparing and amplifying the first detection voltage with a reference voltage to the phase shifter as one of the control signals; A second sub-amplifier that supplies a second output voltage obtained by amplifying the second detection voltage with a reference voltage to the phase shifter as another of the control signals;
The first output signal controls an amplitude value of the one carrier waveform;
The orthogonal carrier generation device according to claim 4, wherein the second output signal controls an amplitude value of the other carrier waveform. The first buffer circuit of the phase shifter has a first bias current source, and the amplitude value of the output varies depending on a current generated by the first bias current source, and The second buffer circuit of the phase shifter has a second bias current source, and the amplitude value of the output varies depending on a current generated by the second bias current source.
The amplitude detector receives the one of the two carrier waveforms, outputs a first detection voltage corresponding to the amplitude value of the one carrier waveform, and the two carrier waveforms. A second sub-detector that inputs the other and outputs a second detection voltage corresponding to the amplitude value of the other carrier waveform;
A first sub-amplifier that supplies a first output voltage obtained by amplifying a difference between the first detection voltage and the reference voltage to the phase shifter as one of the control signals; A second sub-amplifier that supplies a second output voltage obtained by amplifying the difference between the second detection voltage and the reference voltage to the phase shifter as another control signal;
The first output voltage is supplied to the first bias current source of the first buffer circuit, and the current of the first bias current source is controlled by the first output signal;
The second output voltage is supplied to the second bias current source of the second buffer circuit, and the current of the second bias current source is controlled by the second output signal. The orthogonal carrier generation device according to claim 4. A baseband signal processing unit for generating a two-phase baseband signal;
An oscillation waveform is input, two carrier waveforms orthogonal to each other are generated, and a phase shifter configured to be able to control both amplitude values of the two carrier signals by a control signal, of the two carrier waveforms An amplitude detector that outputs at least one of them and outputs a detection voltage corresponding to the amplitude value of the at least one carrier waveform, and an output signal obtained by amplifying the detection voltage by comparison with a reference voltage as the control signal A quadrature carrier generation device including a comparison / amplifier to be supplied to the phase shifter;
A quadrature modulator that quadrature modulates the two carrier signals with the two-phase baseband signal to generate a modulated signal;
A power amplifier that amplifies the modulated signal to generate a power amplified signal;
An antenna for radiating the power amplification signal to a radio wave. An antenna that captures radio waves and outputs RF signals;
An oscillation waveform is input, two carrier waveforms orthogonal to each other are generated, and a phase shifter configured to be able to control both amplitude values of the two carrier signals by a control signal, of the two carrier waveforms An amplitude detector that outputs at least one of them and outputs a detection voltage corresponding to the amplitude value of the at least one carrier waveform, and an output signal obtained by amplifying the detection voltage by comparison with a reference voltage as the control signal A quadrature carrier generation device including a comparison / amplifier to be supplied to the phase shifter;
A quadrature demodulator that demodulates the RF signal with the two carrier signals to generate a two-phase baseband signal;
A wireless receiver comprising: a baseband signal processing unit that performs signal processing on the two-phase baseband signals.

Images