JP6124382B1 - Oscillator, RF front-end circuit, and portable wireless communication terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an oscillation signal with high spectral purity. An oscillator 10 according to an embodiment of the present invention includes an oscillator 11 whose oscillation frequency is not controllable, and a frequency of a primary signal output from the oscillator 11 or an error frequency corresponding to a reference frequency corresponding thereto. And a secondary signal generator 20 for detecting and generating a secondary signal having a target frequency from the primary signal according to the error frequency. The secondary signal generator 20 includes an error frequency detector 12 that detects an error frequency relative to a reference frequency of the frequency of the primary signal or a frequency corresponding thereto, and a correction signal generator 14 that generates a correction signal having a frequency corresponding to the error frequency. And a signal synthesizer 16 that synthesizes the correction signal with the primary signal. [Selection] Figure 1

Description

  The present invention relates to an oscillation device, an RF front end circuit, a wireless transmission / reception circuit, and a portable wireless communication terminal device.

  The amount of communication by wireless communication by mobile terminals such as mobile phones, smartphones, and mobile routers continues to increase year by year as terminal devices become more sophisticated and distribution contents such as moving image files and music files are enhanced. In order to meet such demand, development of wireless communication technology is also progressing. At present, various terminal devices and base station equipment corresponding to the fourth generation (4G) communication standard are widely used, and are widely used in general.

  A signal transmitted and received by the antenna in the wireless communication terminal device as described above is a signal having a high frequency called an RF (Radio Frequency) signal. When the RF signal is received, the RF front-end circuit performs down-conversion by multiplying it with the output signal of the local oscillator, and converts it to a band including information itself exchanged by communication called baseband. To do. In addition, when transmitting information, the baseband signal is multiplied by the output signal of the local oscillator, up-converted, and transmitted from the antenna as an RF signal.

  Generally, an oscillator such as a VCO (Voltage-Controlled Oscillator) is used as the local oscillator. A VCO is an oscillation circuit that controls an output frequency by an input control voltage. Usually, a control voltage is generated by a phase synchronization circuit, and an error caused by various factors is corrected in the frequency of the output signal of the VCO, and used as a local oscillator.

  For example, Patent Document 1 has a configuration in which an output of a VCO is input to an ADC (Analog-to-Digital Converter), a phase comparison is performed using digital data after conversion, and a control voltage of the VCO is output based on the phase comparison. Thus, a phase synchronization circuit for stabilizing the frequency is described.

  In communication after the fourth generation, multilevel modulation such as 256QAM (256 Quadrature Amplitude Modulation) is used. For this purpose, it is necessary to keep the frequency of the local oscillator constant. For this purpose, the frequency of the local oscillator is stabilized by the phase synchronization circuit.

  Further, in the above-mentioned fourth generation communication standard, communication using a plurality of subcarriers called OFDMA (Orthogonal Frequency-Division Multiple Access) is used to improve the efficiency of use of the frequency band. It is increasing. By using a local oscillator having a high spectral purity, it is possible to prevent interference between subcarriers and increase the communication capacity by using the frequency band more efficiently.

  Examples of the oscillator having higher spectral purity include a SAW (Surface Acoustic Wave) oscillator. The SAW oscillator is also used in combination with a phase locked loop and its output frequency is stabilized. In order to stabilize the frequency of the SAW oscillator, a technique by adjusting the voltage applied to the varicap (variable capacitance diode) is mainly used.

  Further, MIMO (Multiple-Input and Multiple-Output) is known as a technique for increasing the capacity of wireless communication. This is to increase the communication capacity by using a plurality of transmission / reception systems including an antenna, a modulator, a demodulator, etc. in both of the transceivers used for wireless communication.

JP 2000-138581 A

  As described above, in a current wireless communication terminal device, a VCO is generally used as a local oscillator. As described above, one technique for increasing the communication capacity is to increase the spectral purity of the local oscillator, but there is a limit to increasing the spectral purity of the VCO. Since the SAW oscillator is an oscillator having a spectral purity higher than that of the VCO, if it can be used as a local oscillator, an increase in communication capacity can be expected. However, the SAW oscillator has a problem that the oscillation frequency fluctuates due to external impact or temperature fluctuation. When used in a wireless communication device such as a cellular phone, the above-described frequency stabilization by the varicap can obtain a stable output frequency when the frequency variation due to temperature variation deviates from the frequency correction range. There was a problem that it was impossible. Further, the SAW oscillator has a fixed nominal frequency and cannot be used for applications that oscillate a plurality of frequencies such as a local oscillator of a mobile phone terminal.

  Accordingly, one of the objects of the present invention is to provide an oscillation device using an oscillator whose oscillation frequency is uncontrollable, and an RF front-end circuit, a wireless transmission / reception circuit, and a portable wireless communication terminal device using the oscillation device. There is. Assume that a SAW oscillator is used as an oscillator whose oscillation frequency is uncontrollable. This oscillation device stabilizes the frequency of a signal output from an oscillator whose oscillation frequency is uncontrollable, thereby generating an oscillation signal with high spectral purity.

  An oscillation apparatus according to an embodiment of the present invention detects an error frequency with respect to a reference frequency of an oscillator whose oscillation frequency is uncontrollable, a frequency of a primary signal output from the oscillator, or a frequency corresponding thereto, according to the error frequency. And a secondary signal generator for generating a secondary signal having a target frequency from the primary signal.

  The secondary signal generation unit includes an error frequency detection unit that detects an error frequency relative to a reference frequency of the frequency of the primary signal or a frequency corresponding thereto, a correction signal generation unit that generates a correction signal of a frequency corresponding to the error frequency, and a primary signal A signal synthesis unit that synthesizes the correction signal with the signal.

  The error frequency detector includes an analog-digital converter that converts a primary signal output from the oscillator into a digital primary signal, a reference signal generator that generates a digital reference signal indicating a waveform of a reference frequency, a digital reference signal, and a digital An error frequency calculation unit for calculating an error frequency based on the primary signal. The correction signal generation unit includes a digital correction signal generation unit that generates a digital correction signal indicating a waveform of a frequency corresponding to the error frequency, and a digital-analog conversion unit that converts the digital correction signal into an analog signal. The digital correction signal generation unit generates a digital correction signal based on the error frequency and the predetermined frequency.

  In this way, by synthesizing the correction signal generated based on the difference between the frequency of the output signal of the oscillator and the target frequency with respect to the oscillation signal of the oscillator, even when the frequency of the output signal of the oscillator is unstable, It can be stabilized. Unlike conventional phase-locked loops, the oscillator is not controlled, so it can be said to be phase stabilization control by feedforward.

  When the oscillation frequency of the oscillator fluctuates due to the impact described above, the resistance to impact and the low phase noise outside the loop band cannot be achieved with feedback control as in the conventional phase locked loop circuit. In order to obtain impact resistance, it is necessary to widen the loop band in the conventional feedback control. On the other hand, due to the problem of the stability of the loop band, the spectral purity is deteriorated by widening the loop band. In this method, since feedforward control is used, the problem of stability of the loop band is not restricted, and the spectral purity is not impaired while expanding the loop band. That is, both impact resistance and spectral purity can be achieved.

  In contrast to the fluctuation of the oscillation frequency of the oscillator due to the temperature fluctuation described above, the phase synchronization circuit using the conventional varicap does not operate normally when the temperature fluctuation range of the frequency exceeds the frequency adjustment range using the varicap. When the correction signal is generated by the DAC of the present invention, it is possible to generate a signal in a frequency range that can sufficiently cover frequency fluctuation due to temperature.

  When the correction signal is generated by the DAC, the frequency of the sine wave generated by the DAC is assumed to be several tens of megahertz at the maximum. Due to the characteristics of the DAC, it is easy to generate a sine wave having excellent spectral purity at this frequency, and the spectral purity of the obtained output is not impaired by the DAC.

  The error frequency correcting DAC can also serve as a modulation operation and has excellent compatibility with a digital modulation / demodulation wireless device.

  Furthermore, in one embodiment of the present invention, a SAW oscillator can be applied as an oscillator whose oscillation frequency is uncontrollable. This stabilizes the phase of the output signal and shifts the frequency of the SAW oscillator, which has a high spectral purity but is susceptible to temperature changes and external shocks, and has a fixed nominal frequency. A signal having a stable frequency can be provided.

  The secondary signal generation unit includes a BPF provided in a subsequent stage of the signal synthesis unit and having a pass band centered on the target frequency. By providing the BPF, it is possible to remove the local leak signal and the image signal that are output from the signal synthesis unit due to a manufacturing error or the like, or to reduce the signal level of the local leak signal and the signal level of the image signal. Can be increased.

  An oscillation device according to an embodiment of the present invention includes an oscillator whose oscillation frequency is uncontrollable, a channel signal output unit that selectively outputs a plurality of channel signals having different frequencies, and a channel for the oscillation signal output from the oscillator. A signal synthesis unit that synthesizes the channel signals output from the signal output unit. Thereby, it is possible to shift the frequency of a signal output from a SAW oscillator whose oscillation frequency is conventionally uncontrollable.

  An RF front-end circuit according to an embodiment of the present invention performs conversion of a received signal received by an antenna into a baseband input signal and conversion of a baseband signal output from the baseband into a transmission signal transmitted by the antenna. . The RF front-end circuit detects an oscillator whose oscillation frequency is uncontrollable, and an error frequency of the primary signal output from the oscillator or a frequency corresponding thereto with respect to a reference frequency, and determines the target frequency from the primary signal according to the error frequency. A secondary signal generator that generates a secondary signal of frequency, a first multiplier that multiplies the received signal by the secondary signal and outputs a baseband input signal, and multiplies the baseband output signal by the secondary signal; A second multiplier for outputting a transmission signal. As described above, by configuring the RF front-end circuit using the oscillation device according to the embodiment of the present invention, stable operation can be expected even when using a local oscillator that is weak against temperature change and external shock. . Of course, a SAW oscillator can be used as an oscillator whose oscillation frequency is uncontrollable, thereby providing a local oscillation signal with high spectral purity and increasing the communication capacity.

  A portable wireless communication terminal apparatus according to an embodiment of the present invention includes the RF front end circuit described above. As a result, the effect of the RF front-end circuit enables stable wireless communication even in a portable terminal device exposed to, for example, a temperature change or an external impact.

  A radio transmission / reception circuit according to an embodiment of the present invention converts a received signal received by an antenna into input data and converts output data into a transmission signal transmitted from the antenna. The wireless transmission / reception circuit includes an oscillator whose oscillation frequency is uncontrollable, a reference signal generator that generates a digital reference signal indicating a waveform of the reference frequency, and a first analog that converts a primary signal output from the oscillator into a digital primary signal A digital converter, an error frequency detector for detecting an error frequency relative to a reference frequency of the frequency of the primary signal or a frequency based on the digital primary signal and the digital reference signal, and a waveform of the frequency corresponding to the error frequency A digital correction signal generator for generating a digital correction signal indicating a first signal, a first multiplier for multiplying the received signal by a primary signal and generating a baseband input signal, and converting the baseband input signal into a digital baseband input signal A second analog-to-digital converter, and a second that multiplies the digital baseband input signal by the digital correction signal. A demodulator that demodulates the digital input signal output from the calculator and the second multiplier, generates input data, a modulator that modulates output data and generates a digital output signal, and digitally corrects the digital output signal A third multiplier that multiplies the signal to generate a digital baseband output signal, a digital-to-analog converter that converts the digital baseband output signal to an analog baseband output signal, and a primary signal that multiplies the analog baseband output signal And a fourth multiplier for generating a transmission signal. Thus, by adopting a configuration in which correction of the frequency error of the local oscillator is performed at the time of demodulation and modulation, the number of DACs necessary for the configuration can be reduced, and the manufacturing cost and power consumption can be suppressed. Note that the radio transmission / reception circuit according to an embodiment of the present invention can be applied to MIMO, which is a radio communication technology that transmits and receives data with a plurality of antennas. A radio transmission / reception circuit applied to MIMO includes a plurality of transmission / reception paths respectively corresponding to a plurality of antennas.

  A radio transmission / reception circuit according to an embodiment of the present invention converts a first reception signal received by a first antenna and a second reception signal received by a second antenna into input data, and outputs the output data. Conversion to a first transmission signal transmitted from one antenna and a second transmission signal transmitted from a second antenna is performed. The wireless transmission / reception circuit includes an oscillator whose oscillation frequency is uncontrollable, a reference signal generator that generates a digital reference signal indicating a waveform of the reference frequency, and a first analog that converts a primary signal output from the oscillator into a digital primary signal A digital converter, an error frequency detector for detecting an error frequency relative to a reference frequency of the frequency of the primary signal or a frequency based on the digital primary signal and the digital reference signal, and a waveform of the frequency corresponding to the error frequency A digital correction signal generator for generating a digital correction signal indicating a first signal, a first multiplier for multiplying the first received signal by a primary signal, and a first multiplier for generating a first baseband input signal, and a second signal multiplied by the primary signal A second multiplier for generating a second baseband input signal, and converting the first baseband input signal to a first digital baseband input signal A second analog-digital converter, a third analog-digital converter that converts the second baseband input signal into a second digital baseband input signal, and a digital correction signal multiplied by the first digital baseband input signal. A third multiplier for generating a first digital input signal, a fourth multiplier for multiplying the second digital baseband input signal by a digital correction signal and generating a second digital input signal, and a first digital input signal The first demodulator that demodulates and generates the first demodulated data, the second demodulator that demodulates the second digital input signal and generates the second demodulated data, and the first demodulated data and the second demodulated data are integrated. A data integration unit that generates output data, a data division unit that divides the output data into first divided data and second divided data, and modulates the first divided data and outputs the first digital output. A first modulation unit for generating a signal, a second modulation unit for modulating the second divided data and generating a second digital output signal, a first digital output signal multiplied by a digital correction signal, and a first digital baseband A fifth multiplier for generating an output signal; a sixth multiplier for multiplying the second digital output signal by a digital correction signal to generate a second digital baseband output signal; and a first digital baseband output signal as a first A first digital-analog converter for converting an analog baseband output signal; a second digital-analog converter for converting a second digital baseband output signal to a second analog baseband output signal; and a first analog baseband output A seventh multiplier that multiplies the signal by the primary signal and generates a first transmission signal; a second analog baseband output signal that is multiplied by the primary signal; And an eighth multiplier for generating a communication signal. In this way, the communication capacity can be increased by adopting a configuration including a plurality of transmission / reception paths. Here, an example in which the wireless transmission / reception circuit includes two transmission / reception paths has been described, but, of course, the transmission / reception paths may be four systems or the like.

  The frequency can be stabilized by correcting the frequency error of the output signal by a method of synthesizing the frequency correction signal with the output signal of the oscillator. Thereby, it is possible to provide a wireless transmission / reception circuit capable of increasing the communication capacity.

1 is a block diagram illustrating a configuration of an oscillation device according to a first embodiment of the present invention. It is a block diagram which shows the structure of the error frequency detection part of FIG. It is a block diagram which shows the structure of the correction signal generation part of FIG. 1, and the structure of a signal synthetic | combination part. It is a figure which shows an example of the frequency spectrum of the secondary signal before BPF passage of FIG. It is a figure which shows an example of the frequency spectrum of the secondary signal after BPF passage of FIG. It is a figure which shows the other example of the frequency spectrum of the secondary signal before BPF passage of FIG. It is a figure which shows the other example of the frequency spectrum of the secondary signal after BPF passage of FIG. It is a flowchart which shows the error frequency correction process by the secondary signal generation part of FIG. It is a block diagram which shows the structure of the radio | wireless transmission / reception circuit which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the procedure of the data reception process by the radio | wireless transmission / reception circuit which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the procedure of the transmission process of the data by the radio | wireless transmission / reception circuit which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless transmission / reception circuit which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the procedure of the detection process of the error frequency in 3rd Embodiment of this invention. It is a flowchart which shows the procedure of the data reception process by the radio | wireless transmission / reception circuit which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the procedure of the transmission process of the data by the radio | wireless transmission / reception circuit which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless transmission / reception circuit which concerns on 4th Embodiment of this invention. It is a flowchart which shows the procedure of the data reception process by the radio | wireless transmission / reception circuit which concerns on 4th Embodiment of this invention. It is a flowchart which shows the procedure of the transmission process of the data by the radio | wireless transmission / reception circuit which concerns on 4th Embodiment of this invention. It is a block diagram which shows the structure of the oscillation apparatus which concerns on 5th Embodiment of this invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of an oscillation device 10 according to the first embodiment. FIG. 2 is a block diagram showing a configuration of the error frequency detection unit 12 of FIG. FIG. 3 is a block diagram showing the configuration of the correction signal generator 14 and the signal synthesizer 16 of FIG.

  In the oscillation device 10 according to the first embodiment, an oscillator 11 whose oscillation frequency is uncontrollable and an oscillation signal LS1 (hereinafter also referred to as a primary signal) of the oscillator 11 are set to a difference between a frequency f1 of the primary signal LS1 and a predetermined frequency. The secondary signal generation unit 20 generates a secondary signal LS2 by performing frequency conversion accordingly. The oscillator 11 whose oscillation frequency is not controllable is typically a SAW oscillator, not a VCO (Voltage-Controlled Oscillator) that can vary the oscillation frequency according to the voltage. Hereinafter, the oscillator 11 whose oscillation frequency cannot be controlled is referred to as a SAW oscillator 11. The oscillator 11 whose oscillation frequency is uncontrollable may be an oscillator using sapphire, diamond or the like as a vibrator.

As already described, the oscillation frequency f1 of the SAW oscillator 11 is in a range of about 0.01% of the frequency f0 with respect to the predetermined frequency f0 of the SAW oscillator 11 due to various factors such as physical shock. (Equation (1)). Here, the error frequency of the frequency f1 of the primary signal LS1 output from the SAW oscillator 11 with respect to the natural frequency f0 of the SAW oscillator 11 is expressed as f _err . Ideally, the error frequency f _err is zero.

f1 = f0 + f _err (1)
On the other hand, as shown in Expression (2), the target frequency f _tgt is a frequency shifted by the frequency fs with respect to the natural frequency f0. The frequency fs (hereinafter also referred to as shift frequency fs) is preferably a frequency selected from a range of about ± 5% of the frequency f1 of the primary signal output from the SAW oscillator 11. Note that the target frequency f _tgt may be the natural frequency f0.

f _tgt = f0 + fs (2)
The secondary signal generator 20 performs a feedforward process on the primary signal LS1 of the SAW oscillator 11, detects the frequency f1 of the primary signal LS1 or the error frequency f _err with respect to the reference frequency f _ref of the frequency corresponding thereto, A secondary signal LS2 having a target frequency f _tgt is generated from the primary signal LS1 according to the error frequency f _err .

Secondary signal generator 20, a frequency corresponding to it the frequency f1 or the primary signal LS1, the error frequency detection unit 12 for detecting an error frequency _{f err} against natural frequency f0 of the SAW oscillator 11, a frequency corresponding to the error frequency _{f err} A correction signal generator 14 for generating the correction signal LScor, a signal synthesizer 16 for synthesizing the correction signal LScor with the primary signal LS1, and a pass band centered on the target frequency f _tgt provided at the subsequent stage of the signal synthesizer 16. Has BPF18. The error frequency detector 12 and the correction signal generator 14 are mounted on a microprocessor for performing digital signal processing, such as a digital signal processor (DSP). Note that a CPU (Central Processing Unit) or the like may be used instead of the DSP. However, since the oscillation device 10 performs feedforward processing on the primary signal LS1, the error frequency detection unit 12 and the correction signal generation unit 14 are required to perform high-speed processing. In order to cope with this, it is preferable to use a DSP.

The error frequency detector 12 includes an analog-digital converter (ADC) 121, a multiplier 122, an NCO 123, a reference frequency output unit 124, a low-pass filter (LPF) 125, and an error frequency calculator 126. More specifically, in the calculation of the error frequency f _err by the error frequency detection unit 12, N times the reference frequency f _ref (N is an arbitrary number) becomes the natural frequency f0, or the frequency of the reference frequency f _ref The reference frequency f _ref is used such that 1 / N of the frequency becomes the natural frequency f0.

The ADC 121 converts the primary signal LS1 output from the SAW oscillator 11 into a digital primary signal LS1 ′. Since the oscillation frequency f0 of the SAW oscillator 11 is higher than a reference frequency f _ref described later, it is assumed that the ADC 121 converts the primary signal LS1 into the digital primary signal LS1 ′ by undersampling.

The reference frequency output unit 124 generates a digital reference signal LSref indicating the waveform of the reference frequency f _ref . The digital reference signal LSref is a signal obtained by digitally converting an oscillation signal of a crystal oscillator, for example. As described above, the oscillation device 10 is intended to obtain a local oscillator output signal used in the wireless transmission / reception circuit. Therefore, the target frequency f _tgt of the secondary signal LS2 of the oscillation device 10 is a high frequency band such as several hundred megahertz to several gigahertz. On the other hand, the reference frequency f _ref may be about several tens of megahertz, which is lower than the target frequency f _tgt . If it is about several tens of megahertz, it is possible to stably output an oscillation signal having a reference frequency f _ref by a crystal oscillator. The digital reference signal LSref generated by the reference frequency output unit 124 is input to the NCO 123.

The NCO 123 and the multiplier 122 constitute a PLL circuit for the digital primary signal LS1 ′ converted by the ADC 121. The multiplier 122 multiplies the digital primary signal LS1 ′ by the output signal of the NCO 123. An output signal of the multiplier 122 is input to the NCO 123 and the LPF 125. The NCO 123 operates at the reference frequency f _ref and outputs a frequency signal representing the frequency and phase of the primary signal LS1. The NCO 123 operates at the reference frequency f _ref , and the frequency of the oscillator output is detected based on the reference frequency.

  The LPF 125 is inserted after the multiplier 122. The LPF 125 removes high frequency noise included in the value indicating the frequency output from the multiplier 122. Generally, it is preferable that the loop bandwidth of the PLL circuit is as wide as possible. As the loop band is wider, the digital NCO 123 faithfully follows the output of the SAW oscillator 11. However, as the loop band is increased, noise is generated at a higher offset frequency while following the frequency f1 of the primary signal LS1 output from the SAW oscillator 11 due to the conversion noise of the ADC 121. Even in the conventional phase-locked loop, noise is generated at a high offset frequency when the loop band is widened in order to improve the shock resistance. However, it is difficult to insert an LPF in order to remove noise with a high offset frequency in the conventional phase locked loop. The conventional phase locked loop circuit is feedback control, and the control becomes unstable by LPF insertion.

The error frequency calculator 126 calculates the error frequency f _err based on the digital reference signal and the digital primary signal. Specifically, the error frequency calculation unit 126 specifies the value of the frequency f1 of the primary signal LS1 based on the digital reference signal and the digital primary signal, and sets the specified frequency value to the value of the natural frequency f0. Subtract. Thereby, the error frequency f _err is calculated. As shown in Equation (3), the error frequency f _err is the difference between the natural frequency f0 of the SAW oscillator 11 and the frequency f1 of the primary signal actually output from the SAW oscillator 11.

f _err = f0−f1 (3)
In addition, the error frequency calculation unit 126 calculates the correction frequency f _cor based on the error frequency f _err and the shift frequency fs. The shift frequency fs is a difference between the target frequency f _tgt and the natural frequency f0 of the SAW oscillator 11. As shown in Expression (4), the correction frequency f _cor is the sum of the error frequency f _err and the shift frequency fs. That is, the correction frequency f _cor can be expressed by the difference between the frequency of the primary signal LS1 actually output from the SAW oscillator 11 and the target frequency f _tgt . The error frequency f _err is about 0.01% of the natural frequency f0, and the shift frequency fs is about 5% of the frequency f0. When the frequency f0 is about 1 gigahertz, the correction frequency f _cor is about several tens of megahertz.

f _cor = f _err + fs = (f 0 −f 1) + (f _tgt −f 0) = f _tgt −f 1 (4)
The correction signal generation unit 14 includes a reference frequency output unit 141, a digital correction signal generation unit 143, and a digital-analog conversion unit 145 (DAC 145). The reference frequency output unit 141 of the correction signal generation unit 14 may be shared with the reference frequency output unit 124 of the error frequency detection unit 12. Digital correction signal generator 143 generates a digital correction signal LScor indicating the frequency of the waveform corresponding to the error frequency f _err. Specifically, the digital correction signal generator 143 generates a digital correction signal LScor indicating a waveform of the correction frequency f _cor calculated based on the error frequency f _err and the shift frequency fs. The DAC 145 converts the digital correction signal LScor into an analog correction signal LScor ′.

The digital correction signal generator 143 is typically composed of an NCO. The digital correction signal generator 143 is driven with the reference frequency f _ref and generates a digital correction signal LScor corresponding to the correction frequency f _cor . The digital correction signal generation unit 143 includes two output terminals. The digital correction signal generator 143 outputs digital correction signals LScor1 and LScor2 indicating two sine waves whose phases are different by 90 degrees according to the correction frequency f _cor .

  Here, the DAC 145 includes two DACs 146 and 147. The DAC 146 converts the digital correction signal LScor1 output from the digital correction signal generator 143 from digital to analog, and generates an analog correction signal LScor1 ′. The DAC 147 converts the digital correction signal LScor2 output from the digital correction signal generator 143 from digital to analog, and generates an analog correction signal LScor2 ′.

  The signal synthesis unit 16 includes a 90-degree phase shifter 161, multipliers 163 and 165, and an adder 167. The signal synthesizer 16 is typically provided by a quadrature modulator or an IQ modulator. The 90-degree phase shifter 161 generates a primary signal LS11 in which the phase of the primary signal LS1 output from the SAW oscillator 11 is changed by 90 degrees. The multiplier 163 multiplies the primary signal LS1 output from the SAW oscillator 11 and the analog correction signal LScor1 ′ output from the DAC 146 to generate a multiplication signal LS21. The multiplier 165 multiplies the primary signal LS11 output from the 90-degree phase shifter 161 and whose phase is changed by 90 degrees and the analog correction signal LScor2 ′ output from the DAC 147 to generate a multiplication signal LS22. The adder 167 adds the multiplication signal LS21 output from the multiplier 163 and the signal LS22 output from the multiplier 165, and generates a secondary signal LS2.

For example, when the digital correction signal generator 143 is set to generate a digital correction signal LScor1 having a phase of 0 degrees and a digital correction signal LScor2 having a phase of 90 degrees, the secondary signal LS2 output from the signal synthesizer 16 is set. Has a spectral distribution as shown in FIG. That is, the frequency f2 of the secondary signal LS2 output from the signal synthesizer 16 is shifted to a frequency that is lower than the frequency f1 of the primary signal of the SAW oscillator 11 by the correction frequency _fcor .

On the other hand, when the digital correction signal generator 143 is set to generate a digital correction signal LScor1 having a phase of 90 degrees and a digital correction signal LScor2 having a phase of 0 degrees, the secondary signal LS2 output from the signal synthesizer 16 is set. Has a spectral distribution as shown in FIG. That is, the frequency f2 of the secondary signal LS2 output from the signal synthesizer 16 is shifted to a frequency that is higher than the frequency f1 of the primary signal of the SAW oscillator 11 by the correction frequency _fcor .

Note that the processing executed from the digital correction signal generator 143 to the signal synthesizer 16 shifts the frequency of the secondary signal LS2 to a frequency higher than the frequency f1 of the primary signal LS1, or from the frequency f1 of the primary signal LS1. Whether to shift to a lower frequency is selected according to the sign of the correction frequency f _cor . When the sign of the correction frequency f _cor is negative, the frequency f2 of the secondary signal LS2 is shifted to a frequency lower than the frequency f1 of the primary signal LS1 by the process executed from the digital correction signal generator 143 to the signal synthesizer 16. Let When the sign of the correction frequency f _cor is positive, the frequency f2 of the secondary signal LS2 is shifted to a frequency higher than the frequency f1 of the primary signal by processing executed from the digital correction signal generator 143 to the signal synthesizer 16.

The BPF 18 reduces the local leak signal of the SAW oscillator 11 and the image signal of the secondary signal LS2 generated by the signal synthesis unit 16. This is because the signal synthesizer 16, for example, the I signal synthesizer (IQ modulator) 16 is a manufacturing error and outputs unintended components called an image signal and a local leak signal. These cause the spectral purity of the SAW oscillator 11 to deteriorate. Therefore, the BPF 18 is provided at the subsequent stage of the signal synthesis unit 16, and the secondary signal LS <b> 2 output from the signal synthesis unit 16 is passed through the BPF 18. The secondary signal LS2 after passing through the BPF 18 is denoted as LS2 ′. Thereby, for example, the secondary signal LS2 having the frequency spectrum distribution as shown in FIG. 4 shows the frequency spectrum distribution as shown in FIG. 5 by passing through the BPF 18. Similarly, the secondary signal LS2 having the frequency spectrum distribution as shown in FIG. 6 shows the frequency spectrum distribution as shown in FIG. 7 by passing through the BPF 18. As in the first embodiment, the SAW oscillator 11 whose natural frequency is different from the target frequency f _tgt is used, and the shift frequency fs between the target frequency f _tgt and the natural frequency f0 of the SAW oscillator 11 and the error frequency f _err By making the correction frequency f _cor represented by the sum to be several tens of megahertz, the frequency f2 of the secondary signal LS2 is separated from the frequency of the local leak signal and the frequency of the image signal, whereby the dielectric A local band pass filter can easily remove local leaks and image frequencies.

  When the signal strength of the local leak signal and the signal strength of the image signal are sufficiently small with respect to the signal strength of the secondary signal LS2, or the frequency of the local leak signal and the frequency of the image signal are the frequency f2 of the secondary signal LS2. The BPF 18 may be omitted when the local leak signal and the image signal generated from the signal synthesizer 16 may be ignored, such as when they are sufficiently separated from each other.

FIG. 8 is a flowchart showing a correction process of the primary signal LS1 output from the SAW oscillator 11 by the secondary signal generator 20. In step S11, the ADC 121 converts the primary signal LS1 output from the SAW oscillator into a digital primary signal LS1 ′. In step S12, the error frequency f _err is detected based on the digital primary signal LS1 ′ and the reference frequency signal LSref. In step S13, corresponding to the error frequency _{f err,} specifically error frequency _{f err} and digital correction signal LScor showing waveforms of the calculated corrected frequency _{f cor} based on the shift frequency fs is the digital correction signal generating unit 143 Generated by. In step S14, the DAC 145 converts the digital correction signal LScor into an analog correction signal LScor ′. In step S15, the signal synthesizer 16 synthesizes the analog correction signal LScor ′ with the primary signal LS1 output from the SAW oscillator 11. As a result of the processing in step S15, the secondary signal LS2 is generated from the primary signal LS1 output from the SAW oscillator 11. The secondary signal LS2 has the target frequency f _tgt .

As described above, the oscillation device 10 according to the first embodiment synthesizes the correction signal having the correction frequency f _{cor with} the primary signal LS1 output from the SAW oscillator 11, and thereby the secondary signal having the target frequency f _tgt. LS2 can be output. By the processing by the secondary signal generation unit 20 according to the first embodiment, the frequency can be stabilized while utilizing the spectral purity of the SAW oscillator 11.

  Further, the secondary signal generation unit 20 of the oscillation device 10 according to the first embodiment changes the oscillation frequency of the oscillator such as the SAW oscillator 11 that is difficult to vary by changing the shift frequency fs. It can be said that the circuit realizes intentional variation. When the frequency variable width is large, the spectral purity of the oscillation signal of the SAW oscillator 11 is deteriorated by the correction signal generated by the correction signal generator 14. Therefore, the shift frequency fs is in the range of about ± 5% of the natural frequency of the oscillator. However, the shift frequency fs should not be varied only within this range. If the spectral purity of the SAW oscillator 11 may be greatly deteriorated, the shift frequency fs may be used with a variable width larger than the above range. Good.

(Second Embodiment)
The wireless transmission / reception circuit according to the second embodiment includes the oscillation device 10 according to the first embodiment as a local oscillator. In the radio transmission / reception circuit according to the second embodiment, the secondary signal generated by the oscillation device 10 according to the first embodiment is multiplied by the baseband output signal to generate a transmission signal. Further, the baseband input signal is generated by multiplying the secondary signal generated by the oscillation device 10 according to the first embodiment and the received signal.

FIG. 9 is a block diagram illustrating a configuration of a wireless transmission / reception circuit according to the second embodiment. The wireless transmission / reception circuit according to the second embodiment includes an antenna 70 that transmits / receives a wireless signal, an RF front-end circuit 30, and a baseband processing unit 40. The RF front end circuit 30 converts the received signal RS _rcv received by the antenna 70 into a baseband input signal BS _{in, and} converts the baseband output signal BS _out into a transmission signal RS _snd transmitted by the antenna 70. The baseband processing unit 40 demodulates the baseband input signal _{BS in} generating input data _{D in} to the system 71. In addition, the baseband processing unit 40 modulates the output data _Dout output from the system 71 to generate a baseband output signal _BSout .

The RF front-end circuit 30 includes a SAW oscillator 11, a secondary signal generation unit 20, a transmission / reception changeover switch 39 that switches transmission / reception by the antenna 70, and a bandpass filter 31 that extracts a signal in a necessary frequency band from the reception signal RS _rcv. When a multiplier 33 which multiplies the received signal _{RS rcv} after processing of the secondary signal LS2 and the band-pass filter 31 output from the oscillator 10, to generate a baseband input signal _{BS in,} baseband input signals BS analog converts the _in the digital signal - digital conversion unit and (ADC) 35, digital converts the baseband output signals _{BS out} to an analog signal - analog converter unit (DAC) 34, the secondary output from the oscillator 10 a baseband output signal _{BS out} which is converted into a signal LS2 and the analog signal Calculated by, and a multiplier 32 for generating a transmission signal _{RS snd.}

The baseband processing unit 40 demodulates the baseband input signal BS _in and modulates the demodulating unit 41 that outputs the input data D _in to the system 71, and the output data D _out from the system 71, and the baseband output signal BS and a modulation unit 42 that outputs _out .

Here, the system 71 is an arbitrary system that requests transmission / reception of data by wireless communication. For example, when the wireless transmission / reception circuit according to the second embodiment is used for a mobile phone, a smartphone terminal, or the like, the system 71 is input / output by an OS (Operating 71tem, basic software), and various application programs via the input / output. possible. Or when using the radio | wireless transmission / reception circuit which concerns on 2nd Embodiment for base stations, such as a mobile telephone, it can be a system which manages it. Further, as described above, the secondary signal LS2 is a signal having the target frequency f _tgt obtained by correcting and stabilizing the frequency f1 of the primary signal LS1 output from the SAW oscillator 11.

FIG. 10 is a flowchart illustrating a procedure of RF signal reception processing by the wireless transmission / reception circuit according to the second embodiment. In Figure 10, demodulates the received signal _{RS rcv} received by the antenna 70, the procedure for obtaining input data _{D in} is written. First, in step S21, by applying a band-pass filter 31 the received signal _{RS rcv,} only the frequency band of the signal required from the received signal _{RS rcv} it is extracted. In step S22, the multiplier 33 multiplies the received signal RS _rcv after application of the bandpass filter and the secondary signal LS2 by the multiplier 33 to generate the baseband input signal BS _in . Baseband input signal _{BS in} is converted to a digital signal at step S23. In step S24, the baseband input signal BS _in converted into a digital signal is demodulated, and input data D _in to the system 71 is generated. As described above, the radio transmission / reception circuit according to the second embodiment can demodulate the reception signal RS _rcv to obtain the input data D _in to the system 71.

FIG. 11 is a flowchart illustrating a procedure of RF signal transmission processing by the wireless transmission / reception circuit according to the second embodiment. In Figure 11, modulates the output data _{D out} of the system 71, the processing procedure for obtaining a transmission signal _{RS snd} is marked. In step S31, the output data _Dout output from the system 71 is modulated to generate a baseband output signal _BSout . In step S32, the DAC 34 converts the baseband output signal BS _out into an analog signal. In step S33, the baseband output signal BS _out converted into the analog signal and the secondary signal LS2 output from the oscillation device 10 are multiplied by the multiplier 32, and the transmission signal RS _snd from the antenna 70 is generated. The As described above, the wireless transceiver circuit according to the second embodiment performs modulation processing of the output data D _out from the system 71, it is possible to obtain a transmission signal RS _snd. 10 and the transmission process shown in FIG. 11 can be performed by switching the transmission / reception changeover switch 39, respectively.

  In this way, a wireless transmission / reception circuit incorporating the oscillation device 10 according to the first embodiment can be configured. As a result, the effect of the oscillation device 10 according to the first embodiment can be obtained. For example, even if the frequency of the primary signal output from the SAW oscillator 11 varies due to an external impact or temperature change, The feedforward process of the signal generator 20 can correct the fluctuation and take advantage of the SAW oscillator having high spectral purity.

(Third embodiment)
The wireless transmission / reception circuit according to the third embodiment is obtained by reducing the scale of the circuit configuration of the wireless transmission / reception circuit according to the second embodiment by using the configuration of the oscillation device 10 according to the first embodiment.
FIG. 12 is a block diagram illustrating a configuration of a wireless transmission / reception circuit according to the third embodiment. Note that, in the same embodiment, the same reference numerals are given to components that are basically the same as those in the second embodiment, and the description thereof is simplified.

The wireless transmission / reception circuit according to the third embodiment includes an antenna 70 for transmitting / receiving a wireless signal, an RF front-end circuit 50, and a baseband processing unit 60. The RF front end circuit 50 converts the received signal RS _rcv received by the antenna 70 into a baseband input signal BS _{in, and} converts the baseband output signal BS _out into a transmission signal RS _snd transmitted by the antenna 70. The baseband processing unit 60 demodulates the baseband input signal _{BS in} generating input data _{D in} to the system 71. In addition, the baseband processing unit 40 modulates the output data _Dout output from the system 71 to generate a baseband output signal _BSout .

The RF front-end circuit 50 is output from the SAW oscillator 11, a transmission / reception changeover switch 39 that switches transmission / reception by the antenna 70, a bandpass filter 31 that extracts a signal in a necessary frequency band from the reception signal RS _rcv, and the SAW oscillator 11. obtained by multiplying the primary signal LS1 and receiving the processed signal of the band pass filter 31 _{RS rcv,} a multiplier 33 for generating a baseband input signal _{BS in,} analog converts the baseband input signal _{BS in} the digital signal - A digital converter (ADC) 35, a digital-analog converter (DAC) 34 for converting the baseband output signal BS _out to an analog signal, a primary signal LS1 output from the SAW oscillator 11 and a base converted to an analog signal by multiplying the band output signal _{BS out,} transmission signal And a multiplier 32 for generating the RS _snd.

The baseband processing unit 60 demodulates the baseband input signal _{BS in,} a demodulator 41 which outputs the input data _{D in} to the system 71, modulates the output data _{D out} from the system 71, a baseband output signal BS and a modulation unit 42 that outputs _out .

The baseband processing unit 60 further includes an error frequency detection unit 43 that detects an error frequency f _err , which is an error between the natural frequency f0 of the SAW oscillator 11 and the frequency f1 of the primary signal LS1 output from the SAW oscillator 11. a digital correction signal generator 45 for generating a digital correction signal _{LS cor} in accordance with the corrected frequency _{f cor,} calculated on the basis of the error frequency _{f err} and shift frequency fs, the digital correction signal _{LS cor} to baseband input signals _{BS in} And a digital signal synthesis unit 47 for synthesizing the digital correction signal LS _cor with the baseband output signal BS _out . The digital signal synthesis unit 46 includes a multiplier and a filter for synthesizing the baseband input signal BS _in and the digital correction signal LS _cor . Equation (5), as shown in (6), the baseband input signal _{BS in} the digital correction signal _{LS cor} and the multiplied signal, and frequency of the digital correction signal _{LS cor} baseband input signal _{BS in Are} included, and a frequency component represented by the sum of the frequency component of the baseband input signal BS _{in and} the frequency of the digital correction signal LS _cor . One of the two frequency components is removed or the signal level is reduced by the filter.

BS _in -LS _cor (5)

BS _in + LS _cor (6)
The digital signal synthesizer 47 is obtained by digitally calculating the signal synthesizer 16 of the oscillation device 10 according to the first embodiment. Whether the frequency of the baseband output signal BS _out is shifted to a frequency lower by the correction frequency f _cor . Alternatively, it is possible to easily change or select whether to shift to a higher frequency by the correction frequency f _cor . As a result, when the baseband output signal BS _out and the primary signal LS1 are synthesized later in step S64, the error frequency f _err is corrected and, if necessary, the transmission signal RS _snd frequency-shifted is obtained. Can do.

The target frequency f _tgt is a frequency required for the local oscillator according to the frequency band for transmission / reception, and is a value determined in advance according to the frequency band for transmission / reception by the wireless transmission / reception circuit. There is a difference between the frequency f1 of the primary signal LS1 and the target frequency f _tgt according to the influence of an external shock or temperature change applied to the SAW oscillator 11 and the change of the frequency to be communicated.

In the third embodiment, the RF front end circuit 50 does not correct the frequency of the primary signal LS1 output from the SAW oscillator 11, but uses it as it is as the output of the local oscillator. In the baseband processing unit 60, the digital correction signal LS _cor is combined with the signal before the demodulation process, and is also combined with the signal after the modulation process.

FIG. 13 is a flowchart illustrating a procedure of error detection processing by the wireless transmission / reception circuit according to the third embodiment. In the flowchart of FIG. 13, a procedure for detecting an error generated between the frequency f1 of the primary signal LS1 output from the SAW oscillator 11 and the natural frequency f0 is described. In step S41, the error frequency detector 43 digitally converts the primary signal LS1 output from the SAW oscillator 11. In step S42, the error frequency detector 43 detects a frequency difference f _cor between the frequency f1 of the primary signal LS1 converted into a digital signal and the frequency of the local oscillator required according to the frequency band to be communicated. The The frequency difference f _cor becomes the frequency of the correction signal (correction frequency). In step S43, the digital correction signal generator 45 generates a digital correction signal LS _cor indicating a sine wave having a frequency corresponding to the frequency difference f _cor . Note that the error detection processing by the wireless transmission / reception circuit according to the third embodiment is the same as the processing until the digital signal is generated from the primary signal by the secondary signal generation unit 20 of the oscillation device 10 according to the first embodiment. is there. The digital correction signal LS _cor generated in this way is used for correction processing in demodulation processing and modulation processing described later.

FIG. 14 is a flowchart illustrating a procedure of RF signal reception processing by the wireless transmission / reception circuit according to the third embodiment. In Figure 14, demodulates the received signal _{RS rcv} received by the antenna 70, the procedure for obtaining input data _{D in} is written. In step S51, by applying a band-pass filter 31 the received signal _{RS rcv,} only the frequency band of the signal required from the received signal _{RS rcv} is extracted. In step S52, the multiplier 33 synthesizes the reception signal RS _rcv after application of the bandpass filter and the primary signal LS1 to generate the baseband input signal BS _in . Since the primary signal LS1 is used for down-conversion of the received signal RS _rcv , at this point, the baseband input signal BS _in has an error between the frequency f1 of the primary signal LS1 and the target frequency f _tgt. Contains ingredients. Baseband input signal _{BS in} is converted to a digital signal at step S53. In step S54, the digital signal synthesizing unit 46 synthesizes the baseband input signal BS _in converted into the digital signal and the digital correction signal LS _cor . As a result, an error component generated between the frequency f1 of the primary signal LS1 and the target frequency _ftgt is corrected. Then, in step S55, the digital signal output from the digital signal synthesizer 46 is demodulated by the demodulator 41, the input data D _in to the system 71 is generated.

FIG. 15 is a flowchart illustrating a procedure of RF signal transmission processing by the wireless transmission and reception circuit according to the third embodiment. In Figure 15, modulates the output data _{D out} of the system 71, the processing procedure for obtaining a transmission signal _{RS snd} is marked. In step S61, the output data _Dout output from the system 71 is modulated to generate a baseband output signal _BSout . At this time, the baseband output signal BS _out does not include an error frequency between the frequency f1 of the primary signal LS1 and the target frequency f _tgt . In step S62, the digital signal combining unit 47 combines the baseband output signal BS _out and the digital correction signal LS _cor . As a result, a correction signal corresponding to the error frequency is included in the baseband output signal _BSout . Specifically, when the frequency f1 of the primary signal LS1 is smaller than the target frequency f _tgt (f _tgt > f1), the frequency of the baseband output signal BS _out is corrected by the multiplication processing of the digital signal synthesis unit 47. It is shifted to a higher frequency by the frequency f _cor . When the frequency f1 of the primary signal LS1 is larger than the target frequency f _tgt (f _tgt <f1), the frequency of the baseband output signal BS _out is lower by the correction frequency f _cor due to the multiplication processing of the digital signal synthesis unit 47. Shifted to frequency.

In step S63, the DAC 34 converts the baseband output signal BS _out into an analog signal. In step S64, the baseband output signal BS _out converted into the analog signal and the primary signal LS1 are multiplied by the multiplier 32, and the transmission signal RS _snd from the antenna 70 is generated. Error frequency contained in the primary signal LS1 is corrected by the digital correction signal that is included in the baseband output signal BS _out in step S62, the transmission signal RS _snd is assumed not affected by the error. The reception process in FIG. 14 and the transmission process in FIG. 15 can be performed by switching the transmission / reception changeover switch 39, respectively.

  As described above, by using the wireless transmission / reception in the third embodiment, even if the SAW oscillator 11 is used as a local oscillator as it is, the primary signal output from the SAW oscillator 11 is obtained by digital calculation in the baseband processing unit 60. The frequency can be shifted if necessary after correcting the included error frequency.

The wireless transmission / reception circuit according to the third embodiment separates the analog processing unit and the digital processing unit of the oscillation device 10 used in the wireless transmission / reception circuit according to the second embodiment, and separates them from the RF front end circuit 50 and the baseband. The configuration is included in the processing unit 60. With such a configuration, the DAC for converting the digital correction signal into an analog signal and the DAC for converting the baseband output signal BS _out into an analog signal can be used in a single DAC in the oscillation device 10. Can do. Thereby, the wireless transmission / reception circuit according to the third embodiment can reduce the circuit scale and power consumption as compared with the second embodiment.

  The baseband processing unit 60 is realized by a DSP and performs digital computation. Therefore, addition of functions such as error correction digital signal synthesis units 46 and 47 in the baseband processing unit 60 can be easily realized by adding logical processing blocks in the DSP. Therefore, an increase in circuit scale, power consumption, and production cost can be suppressed as compared with a case where a multiplier as an analog element is added.

  Further, if the multipliers 32 and 33, the ADC 35, the DAC 34, the demodulator 41, the modulator 42, the error frequency detector 43 and the like are configured as a single IC (Integrated Circuit), the wireless transmission / reception circuit can be further reduced in scale. Can be

  Also in the third embodiment, the system 71 may be any system that requests transmission / reception of data by wireless communication, and the wireless transmission / reception circuit according to the third embodiment is a mobile phone, a smartphone terminal, or the like. It can be used for various wireless communication devices from terminal devices to equipment such as base stations such as mobile phones.

(Fourth embodiment)
The wireless transmission / reception circuit according to the fourth embodiment includes two transmission / reception circuits and corresponds to the MIMO technology. Thereby, the wireless transmission / reception circuit according to the fourth embodiment can increase the communication capacity compared to the case of using a single transmission / reception circuit.

  FIG. 16 is a block diagram showing a wireless transmission / reception circuit according to the fourth embodiment. In the fourth embodiment, components that are basically the same as those in the second and third embodiments are denoted by the same reference numerals and description thereof is simplified.

As illustrated in FIG. 16, the radio transmission / reception circuit according to the fourth embodiment includes two antennas 400 and 500 that perform transmission and reception of radio signals, an RF front-end circuit 200, and a baseband processing unit 300. The RF front end circuit 200 converts the received signals RS _rcv 1 and RS _rcv 2 received by the antennas 400 and 500 into baseband input signals BS _in 1 and BS _in 2, respectively. Further, the RF front end circuit 200 converts the baseband output signals BS _out 1 and BS _out 2 into transmission signals RS _snd 1 and RS _snd 2 transmitted by the antennas 400 and 500, respectively. The baseband processing unit 300 demodulates the baseband input signals BS _in 1 and BS _in 2 and generates input data D _in to the system 600 by integrating the respective data. The baseband processing unit 300 divides the output data _{D out} outputted from the system 600 by modulating the respective data divided, to produce a baseband output signal _{BS out 1, BS} out 2.

  In the RF front end circuit 200, the SAW oscillator 210 is shared by the first and second transmission / reception systems. The RF front-end circuit 200 has two components other than the SAW oscillator 210 shared by the two transmission / reception systems in order to use each of the two transmission / reception systems.

Specifically, the first transmission / reception system of the RF front-end circuit 200 includes a transmission / reception changeover switch 201 that switches transmission / reception by the antenna 400, a band-pass filter 271 that extracts a signal in a necessary frequency band from the reception signal RS _rcv 1, A multiplier 231 that multiplies the primary signal LS _out 1 output from the SAW oscillator 210 and the received signal RS _rcv 1 processed by the bandpass filter 271 and outputs a baseband input signal BS _in 1, and a baseband input signal ADC 251 for converting BS _in to a digital signal, DAC 261 for converting base band output signal BS _out 1 to an analog signal, primary signal LS _out output from SAW oscillator 210 and base band output signal BS converted to an analog signal multiplication for multiplying the _out 1 And a 241.

Similarly, the second transmission / reception system of the RF front-end circuit 200 includes a transmission / reception changeover switch 202 that switches transmission / reception by the antenna 500, a bandpass filter 272 that extracts a signal in a necessary frequency band from the reception signal RS _rcv 2, and a SAW oscillator. A multiplier 232 that multiplies the primary signal LS _out 2 output from 210 by the reception signal RS _rcv 2 processed by the bandpass filter 272 and outputs a baseband input signal BS _in 2, and a baseband input signal BS _in ADC 252 for converting 2 into a digital signal, DAC 262 for converting baseband output signal BS _out 2 into an analog signal, primary signal LS _out output from SAW oscillator 210 and baseband output signal BS _out converted into an analog signal Multiplier to multiply 2 And a 42.

In the baseband processing unit 300, the error frequency detection unit 330 and the digital correction signal generation unit 340 for generating a digital correction signal are shared by the first and second transmission / reception systems. The error frequency detector 330 detects an error frequency f _err , which is an error between the natural frequency f0 of the SAW oscillator 210 and the frequency f1 of the primary signal LS1, and further corrects the error frequency by adding a shift frequency to the error frequency f _err. The frequency f _cor is calculated. The digital correction signal generator 340 generates a digital correction signal LS _cor indicating a frequency waveform corresponding to the correction frequency f _cor . Similarly to the third embodiment, the error between the frequency f1 of the primary signal LS1 and the target frequency f _tgt is detected and the digital correction signal LS _cor is generated according to the procedure described with reference to FIG. The generated digital correction LS _cor is used for correction processing in demodulation processing and modulation processing described later.

Here, the target frequency f _tgt is a frequency required for the local oscillator according to the frequency band for transmission / reception, and is a value determined in advance according to the frequency band for transmission / reception by the radio transmission / reception circuit. . There is a difference between the frequency f1 of the primary signal LS1 and the target frequency f _tgt according to the influence of an external shock or temperature change applied to the SAW oscillator 11 and the change of the frequency to be communicated. The baseband processing unit 300 includes two components other than the error frequency detection unit 330 and the digital correction signal generation unit 340 that are shared by the two transmission / reception systems, in order to use each of the two transmission / reception systems. .

Specifically, the first transmitting and receiving system of the baseband processing unit 300 demodulates the baseband input signal _{BS in} 1, a demodulation unit 311 that generates input data _{D in} 1, modulates the output data _{D out} 1, A modulation unit 321 that generates a baseband output signal BS _out 1, a digital signal synthesis unit 361 that synthesizes a digital correction signal LS _cor with the baseband input signal BS _in 1 converted into a digital signal, and a baseband output signal BS _out 1 has a digital signal synthesizer 371 for synthesizing the digital correction signal LS _cor .

Similarly, the second transmission and reception systems of the baseband processing unit 300 demodulates the baseband input signal _{BS in} 2, a demodulator 312 which generates an input data _{D in} 2, modulates the output data _{D out} 2, baseband The modulation unit 322 that generates the output signal BS _out 2, the digital signal synthesis unit 362 that synthesizes the digital correction signal LS _cor with the baseband input signal BS _in 2 converted into a digital signal, and the baseband output signal BS _out 2 And a digital signal synthesis unit 372 that synthesizes the digital correction signal LS _cor .

The baseband processing unit 300 receives the input of the input data D _in 1 and D _in 2 demodulated by the demodulation units 311 and 312 in order to remove the influence due to the interference generated by the antennas 400 and 500, and from each input data The interference data separation unit 380 that separates the interference data and the input data D _in 1 and D _in 2 that are excluded from the interference output from the interference data separation unit 380 are integrated to generate the input data D _in to the system 600 And a data dividing unit 310 that divides the output data D _out from the system 600 into two output data D _out 1 and D _out 2.

In the fourth embodiment, as in the third embodiment, the RF front end circuit 200 does not correct the frequency of the primary signal LS1 output from the SAW oscillator 210, and uses it as it is as the output of the local oscillator. The digital correction signal LScor for correcting the error frequency f _err between the frequency f1 of the primary signal LS1 and the natural frequency f0 of the SAW oscillator 210 and the shift frequency fs between the natural frequency f0 and the target frequency f _tgt is a baseband. In the processing unit 300, the signal before the demodulation process and the signal after the modulation process are combined. In the RF signal reception process, the frequency of the primary signal is corrected at the stage of the digital signal synthesis units 361 and 362 of the baseband processing unit 300. In the RF signal transmission process, the correction signal is included in the digital signal combining units 371 and 372 in the baseband processing unit 300, and the primary signal is combined with the baseband output signal including the correction signal. Thus, the frequency of the primary signal is corrected.

FIG. 17 is a flowchart illustrating a procedure of RF signal reception processing of the wireless transmission / reception circuit according to the fourth embodiment. In FIG. 17, the RF signals are received by the antennas 400 and 500, the received signals RS _rcv 1 and RS _rcv 2 are demodulated, the demodulated received signals RS _rcv 1 and RS _rcv 2 are integrated, and the input data D _in is obtained. The procedure is described.

In step S71, the input data D _in 1 of the received signal RS _rcv 1 received by the antenna 400 is demodulated by the first transmission / reception system. The reception process in step S71 is the same as the process described with reference to FIG. 16 of the third embodiment, using the bandpass filter 271, the multiplier 231, the ADC 251, the digital signal synthesis unit 361, and the demodulation unit 311. Is what you do. Note that the demodulation processing here is performed after multiplying the baseband input signal BS _in 1 input to the baseband processing unit 300 and the digital correction signal LS _cor as described with reference to FIG. . As a result, the input data D _in 1 can be generated without being affected by an error between the frequency f1 of the primary signal LS1 output from the SAW oscillator 210 and the target frequency f _tgt .

In step S72, the same process as in step S71 by the first transmission / reception system is performed by the second transmission / reception system. Demodulation processing of received signal RS _rcv 2 received by antenna 500 into input data D _in 2 is performed using bandpass filter 272, multiplier 232, ADC 252, digital signal synthesis unit 362, and demodulation unit 312.
In step S73, the input data D _in 1 and input data D _in 2 generated in steps S71 and S72 are input to the interference data separation unit 380, and the influence of interference by the antennas 400 and 500 is eliminated.

In step S74, the input data D _in 1 and the input data D _in 2 output from the interference data separation unit 380 in step S73 are integrated by the data integration unit 390, and the input data D to the system 600 is integrated. _in is generated. The generated input data D _in is input to the system 600.

FIG. 18 is a flowchart illustrating a procedure of RF signal transmission processing by the wireless transmission / reception circuit according to the fourth embodiment. FIG. 18 shows a procedure from dividing and modulating the output data D _out output from the system 600 to obtain transmission signals RS _snd 1 and RS _snd 2.

In step S81, the output data D _out 1 for outputting the output data D _out output from the system 600 by the data dividing unit 310 from the first transmission / reception system, and the output data D _out for outputting from the second transmission / reception system. Divided into two.

In step S82, the output data D _out 1 is modulated to the transmission signal RS _snd 1 by the antenna 400 by the first transmission / reception system. The transmission process in step S82 is the same as the process described with reference to FIG. 15 in the third embodiment, using the modulation unit 321, the digital signal synthesis unit 371, the DAC 261, and the multiplier 241. In the modulation processing here, as described with reference to FIG. 15, after the output data D _out 2 is modulated by the modulation unit 322, the modulated output data D _out 2 and the digital correction signal LS are modulated. By multiplying by _cor , a correction signal component for correcting the frequency f1 of the primary signal LS1 is included in the baseband output signal _BSout in advance. Thus, when obtained by multiplying the primary signal LS1 as the output of the baseband output signal BS _out and the local oscillator, after correcting the error frequency, it is possible to shift the frequency if necessary.

In step S83, the same process as in step S82 by the first transmission / reception system is performed by the second transmission / reception system. With the second transmission / reception system, the modulation process of the output data D _out 2 to the transmission signal RS _out 2 from the antenna 500 is performed using the modulation unit 322, the digital signal synthesis unit 372, the DAC 262, and the multiplier 242.

  The reception process as shown in FIG. 17 and the transmission process as shown in FIG. 18 can be performed by switching the transmission / reception changeover switches 201 and 202, respectively.

  As described above, by using the radio transmission / reception circuit according to the fourth embodiment, in addition to the increase in communication capacity by using the high spectral purity of the SAW oscillator, the increase in communication capacity by using a plurality of transmission / reception systems. Can be achieved.

  In the fourth embodiment, the configuration having two transmission / reception systems is illustrated, but the wireless transmission / reception circuit may be configured to include more transmission / reception systems. As a result, the communication capacity can be increased.

  Also in the fourth embodiment, the system 600 may be any system that requests transmission / reception of data by wireless communication, and the wireless transmission / reception circuit according to the fourth embodiment is a mobile phone, a smartphone terminal, or the like. It can be used for various wireless communication devices from terminal devices to equipment such as base stations such as mobile phones.

  Alternatively, the modulation units 321 and 322 may control the phase and control the direction and distance in which radio waves are transmitted from the antennas 400 and 500, so that beam forming is possible. With such a configuration, even when the radio transmission / reception circuit according to the fourth embodiment is applied to a base station facility such as a mobile phone, radio waves can be more effectively conveyed.

(Fifth embodiment)
In the oscillation device 10 according to the first embodiment, the SAW oscillator 11 having the natural frequency f0 having a frequency different from the target frequency f _tgt can be used. By target frequency _{f tgt} and frequency used SAW oscillator 11 different natural frequency f0, as compared with the case of using the SAW oscillator 11 of the target frequency _{f tgt,} by increasing the correction frequency fcor intentionally corrected primary signal LS1 The frequency of the local leak signal and the frequency of the image signal included in the secondary signal LS2 after synthesis with the signal LScor can be separated from the target frequency f _tgt . Thereby, even in a state where the local leak signal and the image signal are included in the secondary signal, deterioration of the purity of the frequency spectrum of the secondary signal LS2 can be suppressed. Further, even with an inexpensive BPF 18, it can be expected to remove the local leak signal and the image signal from the secondary signal LS2. In this way, by using the SAW oscillator 11 having the natural frequency f0 that is different from the target frequency f _tgt , the inexpensive BPF 18 can be used or the BPF 18 can be omitted.

However, the oscillation device 10 according to the first embodiment can also be used as a local oscillator that can vary the target frequency f _tgt . When it is not necessary to correct an error between the frequency of the signal output from the oscillator and the natural frequency, for example, when an oscillation signal with a very high spectral purity is not required, the oscillation device 10 according to the first embodiment. The configuration may be simplified.

  FIG. 19 is a block diagram illustrating a configuration of an oscillation device 910 according to the fifth embodiment. The oscillation device 910 according to the fifth embodiment includes an oscillator 911 and a secondary signal generation unit 920 whose oscillation frequency cannot be controlled. Here, the oscillator 911 whose oscillation frequency is uncontrollable is a SAW oscillator. The SAW oscillator 911 outputs a primary signal. The secondary signal generator 920 generates a secondary signal from the primary signal output from the SAW oscillator 911. The frequency of the secondary signal is different from that of the primary signal.

  The secondary signal generation unit 920 includes a channel signal output unit 914 and a signal synthesis unit 916. The channel signal output unit 914 selectively outputs a plurality of channel signals having different frequencies. The channel signal output unit 914 has the same configuration as the correction signal generation unit 14 of the first embodiment. That is, the channel signal output unit 914 generates a digital channel signal indicating a frequency difference between a frequency corresponding to a channel designated by a system such as a CPU and a natural frequency of the SAW oscillator 911, and the generated digital channel signal is generated. Convert to analog channel signal. The signal combiner 916 combines the primary signal output from the SAW oscillator 911 and the analog channel signal output from the channel signal output unit 914 to generate a secondary signal. The frequency of the secondary signal generated by the signal synthesis unit 916 has a frequency corresponding to the channel designated by the system.

  The oscillation device 910 according to the fifth embodiment described above can shift the frequency of a signal output from an oscillator whose oscillation frequency is uncontrollable, such as a SAW oscillator, to an intended frequency.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Oscillator, 11 ... SAW oscillator, 12 ... Error frequency detection part, 14 ... Correction signal generation part, 16 ... Signal composition part, 18 ... BPF20 ... Secondary signal generation part

Claims (6)

An oscillator whose oscillation frequency is uncontrollable,
A secondary signal generator that detects an error frequency relative to a reference frequency of a frequency of a primary signal output from the oscillator or a frequency corresponding thereto, and generates a secondary signal of a target frequency from the primary signal according to the error frequency; Comprising
The secondary signal generator is
An error frequency detector that detects an error frequency of the frequency of the primary signal or a frequency corresponding thereto with respect to the reference frequency;
A correction signal generator for generating a correction signal having a frequency corresponding to the error frequency;
A signal synthesizer for synthesizing the correction signal with the primary signal;
The error frequency detector is
An analog-to-digital converter that converts a primary signal output from the oscillator into a digital primary signal;
A reference signal generator for generating a digital reference signal indicating the waveform of the reference frequency;
An error frequency calculation unit for calculating the error frequency based on the digital reference signal and the digital primary signal;
The correction signal generator is
A digital correction signal generator for generating a digital correction signal indicating a waveform of a frequency according to the error frequency;
An oscillation device comprising: a digital-analog conversion unit that converts the digital correction signal into an analog signal. The digital correction signal generator is
Wherein on the basis of the error frequency and the predetermined frequency, the oscillation device according to claim 1, wherein the generating the digital correction signal. The secondary signal generator is
Provided downstream of said signal synthesizer, oscillator apparatus according to claim 1, further comprising a BPF having a pass band centered on the target frequency.   2. The oscillation device according to claim 1, wherein the oscillator whose oscillation frequency is uncontrollable is a SAW oscillator. An RF front-end circuit that converts a received signal received by an antenna into a baseband input signal and converts a baseband output signal output from the baseband into a transmission signal transmitted by the antenna,
An oscillator whose oscillation frequency is uncontrollable,
A secondary signal generator for detecting a frequency of a primary signal output from the oscillator or an error frequency corresponding to a reference frequency of the primary signal and generating a secondary signal of a target frequency from the primary signal according to the error frequency When,
A first multiplier for multiplying the received signal by the secondary signal and outputting the baseband input signal;
A second multiplier for multiplying the baseband output signal by the secondary signal and outputting the transmission signal;
The secondary signal generator is
An error frequency detector that detects an error frequency of the frequency of the primary signal or a frequency corresponding thereto with respect to the reference frequency;
A correction signal generator for generating a correction signal having a frequency corresponding to the error frequency;
A signal synthesizer for synthesizing the correction signal with the primary signal;
The error frequency detector is
An analog-to-digital converter that converts a primary signal output from the oscillator into a digital primary signal;
A reference signal generator for generating a digital reference signal indicating the waveform of the reference frequency;
An error frequency calculation unit for calculating the error frequency based on the digital reference signal and the digital primary signal;
The correction signal generator is
A digital correction signal generator for generating a digital correction signal indicating a waveform of a frequency according to the error frequency;
An RF front-end circuit comprising: a digital-analog conversion unit that converts the digital correction signal into an analog signal . A portable wireless communication terminal apparatus comprising the RF front-end circuit according to claim 5 .

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