WO2019111446A1 - Modulateur δς, émetteur, circuit intégré à semiconducteur et programme informatique - Google Patents

Modulateur δς, émetteur, circuit intégré à semiconducteur et programme informatique Download PDF

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Publication number
WO2019111446A1
WO2019111446A1 PCT/JP2018/029746 JP2018029746W WO2019111446A1 WO 2019111446 A1 WO2019111446 A1 WO 2019111446A1 JP 2018029746 W JP2018029746 W JP 2018029746W WO 2019111446 A1 WO2019111446 A1 WO 2019111446A1
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output
frequency
band
modulator
noise
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PCT/JP2018/029746
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Japanese (ja)
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前畠　貴
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住友電気工業株式会社
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Priority to JP2019557997A priority Critical patent/JP6973503B2/ja
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M3/00—Conversion of analogue values to or from differential modulation
    • H03M3/02—Delta modulation, i.e. one-bit differential modulation

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  • the present invention relates to a ⁇ modulator, a transmitter, a semiconductor integrated circuit, and a computer program.
  • This application claims the priority based on Japanese Patent Application No. 2017-236348 filed on Dec. 8, 2017, and incorporates all the contents described in the Japanese application.
  • Patent Document 1 describes a ⁇ modulator capable of outputting an output signal including a plurality of signals having different frequencies.
  • the ⁇ modulator adds a plurality of input ports to which a plurality of input signals different in frequency are given, a plurality of loop filters provided corresponding to each of the plurality of input ports, and outputs of the plurality of loop filters And an adder.
  • a ⁇ ⁇ modulator includes a first adder that adds a first input signal and a second input signal that are adjacent in frequency, a loop filter, an output of the first adder, and an output of the loop filter.
  • a quantizer that generates quantized data based on the output of the second adder, a feedback signal obtained by feeding back the output of the quantizer, and an output of the first adder
  • a differencer for giving the difference to the loop filter, wherein the loop filter corresponds to the first pass band corresponding to the frequency of the first input signal and the frequency of the second input signal.
  • a transmitter includes the above-described ⁇ modulator and a transmitter to which the output of the quantizer is given.
  • the semiconductor integrated circuit is a semiconductor integrated circuit used for a ⁇ modulator that performs ⁇ modulation on the first input signal and the second input signal whose frequencies are adjacent, and the first input signal
  • the loop filter has a first passband corresponding to the frequency of the first input signal and a second passband corresponding to the frequency of the second input signal, and the frequency of the .DELTA..SIGMA. Modulator Filter characteristic in which one or more of the pole point and the zero point is provided between the first noise stop band corresponding to the first pass band and the second noise stop band corresponding to the second pass band. Have.
  • a computer program is a computer program for causing a computer to execute distortion compensation processing of ⁇ modulation performed on data representing first and second input signals whose frequencies are adjacent to each other.
  • a first addition step of adding the plurality of input signals to a computer, a second addition step of adding the output of the first addition step and the output of the loop filter, and quantization based on the output of the second addition step A quantization data generation step of generating data; a difference step of obtaining a difference between a feedback signal fed back from the output of the quantization data generation step and an output of the first addition step; and outputting the difference to the loop filter ,
  • FIG. 1 is a block diagram showing an example of a transmitter.
  • FIG. 2 is a block diagram showing the configuration of the ⁇ modulator according to the first embodiment.
  • FIG. 3 is a graph showing the frequency-amplitude characteristic of the ⁇ modulator, and shows an example of setting of the upper limit F upper ( ⁇ ) and the lower limit F lower ( ⁇ ).
  • FIG. 4 is a graph showing an example of the frequency-amplitude characteristic by the noise transfer function NTF (z) of the ⁇ modulator according to the present embodiment.
  • FIG. 5A is a diagram showing an example of the arrangement of poles and zeros in the noise transfer function NTF (z) of the ⁇ modulator according to the present embodiment.
  • FIG. 1 is a block diagram showing an example of a transmitter.
  • FIG. 2 is a block diagram showing the configuration of the ⁇ modulator according to the first embodiment.
  • FIG. 3 is a graph showing the frequency-amplitude characteristic of the ⁇ modulator, and shows an example of setting of the upper limit F upper ( ⁇ )
  • FIG. 5B is a diagram showing, as a comparative example, the arrangement of poles and zeros when the noise transfer function NTF (z) is obtained when the first noise rejection band and the second noise rejection band are set independently of each other.
  • . 6 shows the frequency-amplitude characteristics of the noise transfer function NTF (z) of the ⁇ modulator according to the present embodiment shown in FIG. 5A and the frequency-amplitude characteristics of the noise transfer function NTF (z) shown in FIG. 5B. It is the figure which compared.
  • FIG. 7 is a diagram showing an example of a frequency-amplitude characteristic of a conventional ⁇ modulator capable of outputting an output signal including a plurality of signals having different frequencies.
  • a ⁇ ⁇ ⁇ ⁇ modulator capable of outputting an output signal including a plurality of signals having different frequencies can be configured.
  • the ⁇ modulator has a frequency characteristic having a band in which noise is blocked corresponding to the frequency of each of a plurality of input signals. It is necessary to set to such a noise transfer function.
  • FIG. 7 is a diagram showing an example of a frequency-amplitude characteristic of a conventional ⁇ modulator capable of outputting an output signal including a plurality of signals having different frequencies.
  • FIG. 7 shows that in the frequency band corresponding to two input signals different in frequency, there is a band (noise stop band) in which quantization noise is blocked.
  • the quantization noise passed through the loop filter is negatively fed back, but if the power of the quantization noise in a band other than the noise stop band becomes larger than necessary, in the band other than the noise stop band Even quantization noise may be negatively fed back and oscillation may occur. The occurrence of such oscillation may affect the operation of the ⁇ modulator. For this reason, it is preferable to set the frequency-amplitude characteristic so that the power of the quantization noise does not increase more than necessary in a band other than the noise stop band.
  • the amplitude of a band other than the noise blocking band is not increased more than necessary by adjusting the parameter for setting the noise blocking band. It can be adjusted indirectly.
  • the band other than the noise stop band includes the band B located between two noise stop bands arranged adjacent to each other.
  • the amplitude in the band B between the two noise stop bands tends to be relatively larger than the other bands due to the influence of the two noise stop bands because the two noise stop bands are adjacent to each other. Furthermore, the closer the two noise stopbands the higher the tendency. Moreover, even if it is attempted to indirectly adjust the amplitude of the band between both noise stop bands by setting both noise stop bands, it is difficult to properly adjust due to the influence of both noise stop bands. For this reason, in a ⁇ modulator capable of outputting an output signal including a plurality of signals having different frequencies, the amplitude in the band B between the two noise stop bands becomes larger than necessary, and good frequency characteristics can be obtained. There were times when it was difficult.
  • the present disclosure has been made in view of such circumstances, and it is an ⁇ modulator capable of outputting an output signal including a plurality of signals having different frequencies, and a good frequency is obtained even when the frequencies of the signals are close to each other.
  • An object of the present invention is to provide a technique capable of obtaining an amplitude characteristic.
  • a ⁇ modulator includes a first adder that adds a first input signal and a second input signal that are adjacent in frequency, a loop filter, an output of the first adder, and the loop.
  • a second adder for adding the output of the filter, a quantizer for generating quantized data based on the output of the second adder, a feedback signal obtained by feeding back the output of the quantizer, and the first addition Calculating a difference between the output signal of the first input signal and the output of the first input signal and providing the difference to the loop filter, wherein the loop filter has a first pass band corresponding to the frequency of the first input signal and a frequency of the second input signal. Between the first noise stop band corresponding to the first pass band and the second noise stop band corresponding to the second pass band in the frequency characteristic of the ⁇ modulator. , Extreme points and At least one of the zeros have a filter characteristic provided one or more.
  • the ⁇ modulator of the above configuration at least one of the pole point and the zero point is provided between the two noise stop bands adjacent to each other in the frequency characteristic by the noise transfer function of the ⁇ modulator.
  • the frequency characteristic is preferably a filter characteristic as an elliptic function filter or a quasi-elliptic function filter.
  • the pole or zero can be appropriately provided in the band between two adjacent pass bands.
  • the absolute value of the noise transfer function that determines the frequency characteristic is 2 or less.
  • the absolute value of the noise transfer function is 1.5 or less.
  • the frequency characteristic is a filter characteristic as an elliptic function filter or a quasi-elliptic function filter, and an absolute value of the noise transfer function is 1.5 or less.
  • a transmitter includes the ⁇ ⁇ ⁇ modulator according to the above (1), and a transmitter to which an output of the quantizer is given.
  • the semiconductor integrated circuit is a semiconductor integrated circuit used for a ⁇ modulator that performs ⁇ modulation on the first input signal and the second input signal adjacent in frequency, A first adder that adds one input signal and the second input signal; a loop filter; a second adder that adds an output of the first adder and an output of the loop filter; the second adder A quantizer for generating quantization data based on an output of the multiplexer, a difference between a feedback signal obtained by feeding back an output of the quantizer, and an output of the first adder, and the difference is given to the loop filter A differencer, wherein the loop filter has a first passband corresponding to the frequency of the first input signal and a second passband corresponding to the frequency of the second input signal, and the ⁇ modulator Zhou A filter characteristic in which one or more of at least one of a pole point and a zero point is provided between a first noise stop band corresponding to a first pass band and a second noise stop band corresponding to a second pass band in
  • a computer program is a computer program for causing a computer to execute distortion compensation processing of ⁇ modulation performed on data representing the first input signal and the second input signal adjacent in frequency.
  • a first addition step of adding the plurality of input signals to the computer, a second addition step of adding the output of the first addition step and the output of the loop filter, and an output of the second addition step Calculating a difference between the output of the quantization data generation step of generating quantization data and a feedback signal fed back the output of the quantization data generation step and the output of the first addition step, and outputting the difference to the loop filter
  • the filter has a first passband corresponding to the frequency of the first input signal and a second passband corresponding to the frequency of the second input signal, and has a first passband in the frequency characteristic of the ⁇ modulator.
  • a computer program having a filter characteristic in which one or more of a pole point and a zero point are provided between a corresponding first noise rejection band and
  • FIG. 1 is a block diagram showing an example of a transmitter.
  • a transmitter 100 includes a plurality of orthogonal modulation units (primary modulators) 102 and 103 and a ⁇ modulator (secondary modulator) 1.
  • Each of the plurality of quadrature modulation units 102 and 103 is configured as a digital quadrature modulator that performs quadrature modulation on the baseband signal converted into digital data by digital signal processing.
  • the quadrature modulation units 102 and 103 perform quadrature modulation on the baseband signals I 1 , Q 1 , I 2 , and Q 2 as primary modulation.
  • the quadrature modulation units 102 and 103 perform quadrature modulation, up conversion, etc. on the baseband signal, and output an RF (Radio Frequency) signal as digital data.
  • the RF signal is a signal radiated to space as a radio wave, and is a signal used for mobile communication and broadcast service, for example.
  • the quadrature modulation units 102 and 103 are configured to output RF signals U 1 and U 2 of different radio frequencies.
  • the plurality of RF signals U 1 and U 2 become input signals to the ⁇ modulator 1.
  • the ⁇ modulator 1 performs ⁇ modulation as secondary modulation on a plurality of RF signals (input signals) U 1 and U 2 , and a pulse signal (quantized data) including the plurality of RF signals U 1 and U 2 Can be output.
  • Pulse signal ⁇ modulator 1 outputs the frequency RF signals U 1, U 2 as an analog signal into a plurality of RF signals U 1, U 2 corresponding frequency band to each of the frequencies of the frequency band of the pulse signal Contains as an ingredient.
  • the output signal of the ⁇ modulator 1 is applied via the transmission path 104 to the first band pass filter 105 and the second band pass filter 106 which are analog filters.
  • the transmitter 100 of the present embodiment transmits a pulse signal, which is an output signal of the ⁇ ⁇ modulator 1, as a transmission signal.
  • the band pass filters 105 and 106 are provided corresponding to the two RF signals U 1 and U 2 .
  • the first band pass filter 105 has a pass band through which the RF signal U 1 passes.
  • the second band pass filter 106 has a bandpass which passes RF signals U 2.
  • the first band pass filter 105 When the pulse signal output from the ⁇ modulator 1 is applied to the first band pass filter 105, the first band pass filter 105 removes frequency components (such as noise components) out of the band of the RF signal U 1 from the pulse signal. Output a signal. Thus, the first band-pass filter 105 outputs a RF signal U 1.
  • the second band pass filter 106 When the pulse signal output from the ⁇ modulator 1 is supplied to the second band pass filter 106, the second band pass filter 106 outputs a signal obtained by removing frequency components out of the band of the RF signal U 2 from the pulse signal. . Thus, the second band-pass filter 106 outputs a RF signal U 2.
  • These RF signals U 1 and RF signal U 2 is supplied to an amplifier or the like, or is radiated into space as radio waves, or transmitted through a transmission path.
  • the pulse signal which is the output of the transmitter 100 is a digital signal, it is possible to transmit the RF signals U 1 and U 2 as digital signals to a long distance through a high speed transmission line such as an optical fiber. Further, since a plurality of RF signals can be included in one data stream, a plurality of RF signals can be transmitted through a single transmission path.
  • FIG. 2 is a block diagram showing the configuration of the ⁇ modulator 1 according to the first embodiment.
  • the ⁇ modulator 1 includes input ports 2a and 2b to which two RF signals (input signals) U 1 and U 2 having different frequencies are input.
  • the ⁇ modulator 1 outputs from the output port 4 a single output signal V ( ⁇ ⁇ ⁇ ⁇ modulation signal: quantized data) including the two received RF signals U 1 and U 2 .
  • the ⁇ modulator 1 is configured to add a first adder 5 for adding the RF signals U 1 and U 2 (first and second input signals), a loop filter 6, an output of the first adder 5, and a loop filter 6.
  • a first adder 5 for adding the RF signals U 1 and U 2 (first and second input signals)
  • a loop filter 6 an output of the first adder 5, and a loop filter 6.
  • the quantizer 8 for generating quantized data based on the output of the second adder 7, a signal obtained by feeding back the output of the quantizer 8, and the first addition
  • the difference with the output of the unit 5 is obtained, and the difference unit 9 is provided to the loop filter 6.
  • the first adder 5 adds the RF signals U 1 and U 2 received by the input ports 2 a and 2 b.
  • the output of the first adder 5 is given to each of the second adder 7 and the difference unit 9.
  • the differencer 9 receives the output of the first adder 5 and the output signal V output from the quantizer 8 as a feedback signal.
  • the output signal V supplied to the differencer 9 as a feedback signal is fed back via a path 10 connecting the output of the quantizer 8 and the differencer 9.
  • the output signal V fed back to the difference unit 9 through the path 10 is also referred to as a feedback signal.
  • the differencer 9 obtains the difference between the feedback signal and the output of the first adder 5 and outputs the difference to the loop filter 6.
  • the loop filter 6 includes a first filter circuit 15, a second filter circuit 16, and a third adder 18.
  • the first filter circuit 15 and the second filter circuit 16 are connected in parallel to each other with respect to the differentiator 9 and the third adder 18.
  • the output of the difference unit 9 is branched by the branch unit 20 and is given to the first filter circuit 15 and the second filter circuit 16.
  • the third adder 18 adds the output of the first filter circuit 15 and the output of the second filter circuit 16.
  • the output of the third adder 18 is given to the second adder 7 as the output of the loop filter 6.
  • the second adder 7 adds the output of the first adder 5 and the output of the loop filter 6.
  • the output of the second adder 7 is given to the quantizer 8.
  • the quantizer 8 is a two-level quantizer and outputs a 1-bit pulse train as an output signal V. As described above, the output signal V of the quantizer 8 is applied to the loop filter 6 via the path 10 as a feedback signal. The output signal V from the quantizer 8 is given to the output port 4 and outputted.
  • the ⁇ modulator 1 further includes a control unit 19 for controlling the first filter circuit 15 and the second filter circuit 16.
  • the control unit 19 can store a plurality of setting parameters for determining the filter characteristics of the first filter circuit 15 and the second filter circuit 16.
  • the control unit 19 selectively controls the filter characteristics of the first filter circuit 15 and the second filter circuit 16 by selectively supplying the plurality of stored setting parameters to the first filter circuit 15 and the second filter circuit 16. It has a function.
  • the transfer function L (z) of the loop filter 6 is represented by the sum of the transfer function of the first filter circuit 15 and the transfer function of the second filter circuit 16.
  • the transfer function L (z) of the loop filter 6 can be expressed as a sum of polynomials of lower order than the transfer function L (z), as described later.
  • the transfer function L (z) of the loop filter 6 is expressed as the sum of two terms, and the characteristics corresponding to these two terms are set as the characteristics of the first filter circuit 15 and the second filter circuit 16.
  • the transfer function L (z) of the loop filter 6 (the noise transfer function NTF (z) of the ⁇ modulator 1) can be configured by a filter circuit of a transfer function of a lower order than the transfer function L (z). it can.
  • the ⁇ modulator 1 of this embodiment can also be configured by a computer including a CPU, a storage unit, and the like.
  • the computer can realize each functional unit of the ⁇ modulator 1 by reading and executing a computer program and the like stored in the storage unit.
  • the ⁇ modulator 1 processes data representing each signal (such as an input signal and an output signal).
  • the ⁇ modulator 1 of the present embodiment can be configured by, for example, a semiconductor integrated circuit such as an FPGA (Field Programmable Gate Array).
  • a semiconductor integrated circuit such as an FPGA (Field Programmable Gate Array).
  • each function unit such as the loop filter 6 and the quantizer 8 included in the ⁇ modulator 1 is configured using various semiconductor elements included in the semiconductor integrated circuit. Be done.
  • the ⁇ modulator 1 includes an FPGA which is a programmable integrated circuit, and a computer having a function of providing circuit configuration information on the circuit configuration of the FPGA to the FPGA and configuring the circuit on the FPGA according to the circuit configuration information. It can also be configured by another system.
  • the storage unit of the computer stores a program for causing the computer to execute processing for giving circuit configuration information to the FPGA, and one or more pieces of circuit configuration information.
  • the computer provides the circuit configuration information stored in the storage unit to an FPGA.
  • the FPGA given the circuit configuration information configures a circuit in accordance with the given circuit configuration information.
  • the storage unit of the computer stores circuit configuration information indicating a circuit configuration for configuring the ⁇ modulator 1 in the FPGA.
  • the computer can cause the FPGA to configure the ⁇ ⁇ modulator 1 by giving circuit configuration information for configuring the ⁇ modulator 1 to the FPGA.
  • V (z) E (z) + U 1 (z) + U 2 (z) + L (z) (U 1 ( z) + U 2 (z) -V (z)) ⁇ (1)
  • V (z) U 1 ( z) + U 2 (z) + (1 / (1 + L (z)))
  • E (z) U 1 (z) + U 2 (z) + NTF (z) E (z) ⁇ (2)
  • V (z) is an output signal
  • U 1 (z) and U 2 (z) are RF signals
  • L (z) is a transfer function L (z) of the loop filter 6
  • NTF (z) is the noise transfer function of the ⁇ modulator 1
  • E (z) is the quantization noise of the ⁇ modulator 1.
  • the output of the differentiator 9 has an inverse characteristic of the noise component contained in the output signal V (z).
  • the loop filter 6 of the present embodiment has a first passband including the frequency band of the RF signal U1 and a second passband including the frequency band of the RF signal U2, and the first passband and the second passband. In a band other than the band, it is set to have a filter characteristic that blocks the passage of a signal.
  • the loop filter 6 outputs a signal having the inverse characteristic of the noise component in the second pass band including the first pass band including a frequency band of the RF signal U 1, and the frequency band of the RF signal U 2, second This is given to the adder 7.
  • the signal having the inverse characteristic is added by the second adder 7 to the output of the first adder 5 (a signal obtained by adding the RF signals U 1 and U 2 ).
  • the output of the first adder 5 to which the signal having the inverse characteristic is added is quantized by the quantizer 8, and the output signal V is fed back to the loop filter 6.
  • the loop filter 6 of this embodiment outputs a signal having the inverse characteristic of the noise component in the first pass band and the second pass band, when the output from the difference unit 9 is given.
  • the output of the loop filter 6 is repeatedly added to the output of the first adder 5.
  • the noise transfer function NTF (z) of the ⁇ modulator 1 of the present embodiment has two noise rejection bands (a first noise rejection band and a second noise rejection band) at the first pass band and the second pass band by the loop filter 6. It is set to have a frequency-amplitude characteristic (frequency-quantization noise characteristic) having a noise stopband). That is, the noise transfer function NTF (z) that determines the frequency-amplitude characteristic of the ⁇ modulator 1 is set by the filter characteristic of the loop filter 6.
  • the filter characteristic (transfer function L (z)) of the loop filter 6 is set based on the determined noise transfer function NTF (z) after the noise transfer function NTF (z) is determined.
  • the noise transfer function NTF (z) of the ⁇ modulator 1 is configured as an Infinite Impulse Response (IIR) filter. Therefore, the noise transfer function NTF (z) is expressed as the following equation (4).
  • Equation (4) z i and p i are parameters corresponding to the value of i. From equation (4), the noise transfer function NTF (z) can be expressed as a fraction by the denominator polynomial D (z) and the numerator polynomial N (z) as in the following equation (5).
  • the allowable value G may be set to 2. In this case, the degree of freedom in determining the noise transfer function NTF (z) can be increased. However, when importance is placed on stable operation, it is more preferable to set the allowable value G to 1.5 or less.
  • equation (6) If both sides of equation (6) are squared, it can be transformed as equation (7) below.
  • the noise transfer function NTF (z) is determined by determining the parameters a m and b m in the equation (5). Then, in order to obtain the parameters a m and b m in the equation (5), the parameters c m and d m in the equation (7) are found.
  • the parameters a m and b m in the equation (5) can be obtained by substituting the determined parameters c m and d m into the equation (7). As a result, it is possible to obtain the noise transfer function NTF (z) that satisfies the condition limited by the set upper limit F upper ( ⁇ ) and lower limit F lower ( ⁇ ).
  • the noise transfer function NTF (z) of the ⁇ modulator 1 and the frequency transfer characteristic NTF (z) having a plurality of (two) noise stop bands it is necessary to obtain the noise transfer function NTF (z) of the ⁇ modulator 1 and the frequency transfer characteristic NTF (z) having a plurality of (two) noise stop bands.
  • the upper limit value F upper ( ⁇ ) and the lower limit value F lower ( ⁇ ) are appropriately set according to two noise stop bands and a band outside the noise stop band. Find the transfer function NTF (z).
  • the frequency ⁇ is a value in the first noise rejection band and in the second noise rejection band (in the first passband and in the second passband)
  • the upper limit F upper ( ⁇ ) is set to the square of the coefficient ⁇ ( ⁇ 2 ).
  • the frequency omega be a value outside both noise stop band, the upper limit value F upper ( ⁇ ) is set to 1.5 2.
  • the constraint of D (z) ⁇ and N (z) ⁇ with respect to the lower limit F lower ( ⁇ ) is expressed by the following equation (13). Further, the lower limit F lower ( ⁇ ) is obtained by multiplying the upper limit F upper ( ⁇ ) by the square of the coefficient ⁇ ( ⁇ ) ( ⁇ ( ⁇ ) 2 ) as shown in the equation (14). Be That is, the lower limit F lower ( ⁇ ) is set based on the upper limit F upper ( ⁇ ).
  • FIG. 3 is a graph showing the frequency-amplitude characteristic of the ⁇ modulator 1, and shows an example of setting of the upper limit F upper ( ⁇ ) and the lower limit F lower ( ⁇ ).
  • the vertical axis indicates the logarithm of the square of the amplitude.
  • the upper limit F upper ( ⁇ ) and the lower limit F lower ( ⁇ ) are respectively set to discretely set frequencies.
  • a circle indicates that the upper limit F upper ( ⁇ ) is set, and a circle indicates that the lower limit F lower ( ⁇ ) is set.
  • the broken line is a diagram showing the logarithm of the square of the noise transfer function NTF (z) of the ⁇ modulator 1.
  • the frequency f1 is the center frequency of the RF signal U 1
  • the frequency f2 is the center frequency of the RF signal U 2
  • second noise rejection band including the frequency f2 is shown.
  • the upper limit in the frequency of the first noise rejection band and a second noise rejection in band F upper ( ⁇ ) is set to alpha 2. Therefore, the value of the upper limit F upper ( ⁇ ) in FIG. 3 is 10 log 10 ⁇ 2 .
  • ⁇ is set to a value between 0.01 and 0.05.
  • Upper limit F upper in both noise rejection band of the frequency (omega) is set to 1.5 2. Therefore, the value of the upper limit F upper ( ⁇ ) in FIG. 3 is 10 log 10 1.5 2 .
  • the lower limit value F lower ( ⁇ ) at the frequency in both noise stop bands and the frequency outside both noise stop bands is set to a value obtained by multiplying the upper limit value F upper ( ⁇ ) by ⁇ ( ⁇ ) 2 . Therefore, the value of the lower limit F lower ( ⁇ ) in FIG. 3 is a value that is lower than the value of the upper limit F upper ( ⁇ ) by 10 log 10 ⁇ ( ⁇ ) 2 . Note that ⁇ ( ⁇ ) is set to a value between 1 and 10.
  • ⁇ ( ⁇ ) is set to different values depending on whether the frequency ⁇ is a frequency within both noise rejection bands or a frequency outside the noise rejection bands.
  • ⁇ ( ⁇ ) in the case where the frequency ⁇ is a frequency in both noise stop bands is set to a smaller value than in the case where the frequency is outside the both noise stop bands.
  • the difference between the upper limit F upper ( ⁇ ) and the lower limit F lower ( ⁇ ) when the frequency ⁇ is a frequency within both noise stop bands is more than when the frequency is outside the noise stop bands. It is set small.
  • the lower limit value F lower (omega) is the upper limit value F upper ( ⁇ ) It may be set to an independent value.
  • both noise rejection is performed in the frequency characteristic by the noise transfer function NTF (z) obtained by setting upper and lower limits in both noise rejection bands and bands outside both noise rejection bands. Zeros and poles are provided in the band and in bands outside both noise stop bands.
  • a zero point and a pole point are provided in bands outside both noise rejection bands, and therefore, between two noise rejection bands (first noise rejection band and second noise rejection band) adjacent to each other.
  • One or more of the pole point and the zero point are provided in the band of
  • the method of calculating the noise transfer function NTF (z) is, for example, “LAWRENCE R. RABINER, NANCY Y. GRAHAM, AND HOWARD D. HELMS “Linear Programming Design of IIR Digital Filters with Arbitrary Magnitude Function”, IEEE TRANSACTIONS ON ACOUSTICS, SPEECH, AND SIGNAL PROCESSING, VOL. ASSP-22, NO. 2, APRIL 1974 PP. 117-123 ".
  • the above document describes a design method for designing a general low-pass filter having one passband as an elliptic function filter.
  • the filter design method described in the above document is applied to the noise transfer function NTF (z) of the ⁇ ⁇ ⁇ modulator 1.
  • the transfer function L (z) of the loop filter 6 is obtained from the noise transfer function NTF (z) based on the above equation (2).
  • Loop filter 6 which is a transfer function L (z), as well as having a second pass band corresponding to the first pass band and the frequency f2 of the RF signals U 2 corresponding to the frequency f1 of RF signals U 1, .DELTA..SIGMA modulation Has a filter characteristic in which at least one of pole and zero points is provided in a band between both noise stop bands corresponding to both pass bands, which is a band in the frequency characteristic according to the noise transfer function NTF (z) .
  • each term obtained by decomposing the transfer function L (z) into the sum of two terms becomes the transfer function of the first filter circuit 15 and the second filter circuit 16.
  • the transfer functions of the first filter circuit 15 and the second filter circuit 16 thus obtained are reflected in the first filter circuit 15 and the second filter circuit 16 by the control unit 19 (FIG. 2).
  • the ⁇ modulator 1 has frequency-amplitude characteristics based on the noise transfer function NTF (z) obtained by the above method.
  • the ⁇ modulator 1 of the present embodiment in the frequency characteristic by the noise transfer function NTF (z) of the ⁇ modulator 1, at least one of the pole and the zero is in the band between both adjacent noise rejection bands. Since one or more are provided, by adjusting this pole point or zero point, it is possible to suppress the amplitude in the band between both noise stop bands not to be larger than necessary. As a result, the frequency-amplitude characteristics can be set appropriately, and the negative feedback of quantization noise outside both noise stop bands can be suppressed. Thereby, the ⁇ modulator 1 can be operated stably.
  • the frequency characteristics of the ⁇ modulator 1 capable of outputting an output signal including two RF signals different in frequency include two noise stop bands and a band other than the noise stop band where the quantization noise is not suppressed. .
  • bands other than the noise stop band include bands located between the two noise stop bands.
  • the amplitude in the band between both noise stop bands tends to be relatively larger than the other bands due to the influence of both noise stop bands because both noise stop bands are adjacent.
  • the closer the two noise stopbands the higher the tendency.
  • the amplitude in the band between the two noise stop bands may be larger than necessary, and good frequency-amplitude characteristics are obtained.
  • the use frequency band is about 1 GHz. It may be adjacent at intervals.
  • carrier aggregation is performed using a ⁇ ⁇ ⁇ modulator configured to output an output signal including a plurality of signals having different frequencies in such a fifth generation mobile communication system
  • two used frequency bands are 1 GHz. Adjacent intervals may cause the amplitude in a band between both used frequency bands (both noise stop bands) to be relatively larger than other bands.
  • the ⁇ modulator 1 of the present embodiment at least one of the pole point and the zero point is provided in the band between both noise stop bands, so by adjusting the pole point or the zero point
  • the frequency-amplitude characteristic can be set appropriately.
  • the frequency-amplitude characteristic can be appropriately set, and stable operation can be performed.
  • FIG. 4 is a graph showing an example of the frequency-amplitude characteristic by the noise transfer function NTF (z) of the ⁇ modulator 1 of the present embodiment.
  • FIG. 5A is a diagram showing an example of the arrangement of poles and zeros in the noise transfer function NTF (z) of the ⁇ modulator 1 according to this embodiment.
  • FIG. 5B shows, as a comparative example, the arrangement of poles and zeros when the noise transfer function NTF (z) is obtained when the first noise rejection band and the second noise rejection band are set independently of each other.
  • FIG. 10 is a diagram showing the arrangement of poles and zeros in the noise transfer function NTF (z) shown in FIG. 7;
  • the mark shown on the upper side of the drawing showing the noise transfer function NTF (z) is a mark showing the frequency at which the pole point and the zero point are arranged, and the circle mark is where the zero point is arranged. Frequency is shown. Also, crosses indicate the frequency at which the pole point is arranged.
  • zeros are provided in the first noise rejection band and the second noise rejection band, and outside both noise rejection bands. Also poles and zeros are arranged. In particular, two poles are provided in the band A between the first noise rejection band and the second noise rejection band.
  • poles are provided only in both noise rejection bands, so that each pole is on the circumference. It is arranged concentrated on a specific part.
  • the poles and zeros are arranged on the circumference and within the circumference, and the frequency by the noise transfer function NTF (z) of the ⁇ modulator 1 ⁇
  • the amplitude characteristic shows the filter characteristic as an elliptic function filter.
  • FIG. 6 shows the frequency-amplitude characteristics of the noise transfer function NTF (z) of the ⁇ 1 modulator 1 of the present embodiment shown in FIG. 5A, and the frequency-amplitude characteristics of the noise transfer function NTF (z) shown in FIG. Are compared.
  • the solid line shows the noise transfer function NTF (z) of the ⁇ ⁇ modulator 1 of this embodiment shown in FIG. 5A
  • the broken line shows the noise transfer function NTF (z) shown in FIG. 5B.
  • the amplitude in the band A between the first noise rejection band and the second noise rejection band exceeds 5 dB. It has become.
  • the amplitude in the band A is a value close to 0 dB, and it can be understood that the amplitude is suppressed so as not to be larger than necessary.
  • the pole point is in the band A between the first noise blocking band and the second noise blocking band. Two are provided, and by appropriately adjusting this pole point, the amplitude in the band A can be suppressed so as not to be larger than necessary, and a good frequency-amplitude characteristic can be obtained.
  • the embodiments disclosed herein are illustrative and non-restrictive in every respect.
  • the above embodiment shows the ⁇ modulator 1 capable of outputting an output signal including two RF signals U 1 and U 2 having different frequencies (adjacent frequencies are adjacent), it includes a larger number of input signals having different frequencies.
  • a ⁇ modulator capable of outputting an output signal and a good frequency-amplitude characteristic can be obtained. That is, the first adder 5 can add three or more input signals, and the noise transfer function NTF (z) of the ⁇ modulator 1 corresponds to the frequency of each input signal by the loop filter 6. Even in the case where the frequency-amplitude characteristic is set to have a good frequency-amplitude characteristic, it is possible to obtain a good frequency-amplitude characteristic by providing an extreme point between the noise stop bands adjacent to each other.
  • two poles are provided in the band A (FIG. 4) between the first noise stop band and the second noise stop band.
  • one pole may be provided in the band A.
  • one or more zero points may be provided in the band A.
  • both poles and zeros may be provided in the band A.
  • the frequency characteristic of the ⁇ 1 modulator 1 is a filter characteristic as an elliptic function filter, but may be a filter characteristic as a quasi-elliptic function filter. Also in this case, at least one of the pole point and the zero point is provided in the band between the first noise rejection band and the second noise rejection band, thereby obtaining a good frequency-amplitude characteristic. it can.
  • the loop filter 6 is configured by connecting two filter circuits in parallel, but it may be configured using a larger number of filter circuits. Alternatively, the loop filter 6 may be configured by connecting a plurality of filter circuits in series.

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Abstract

La présente invention concerne un modulateur ΔΣ comprenant : un premier additionneur qui additionne un premier signal d'entrée et un deuxième signal d'entrée ayant des fréquences adjacentes l'une à l'autre ; un filtre de boucle ; un deuxième additionneur qui additionne une sortie du premier additionneur et une sortie du filtre de boucle ; un quantificateur qui génère des données quantifiées sur la base de la sortie du deuxième additionneur ; et un différentiateur qui obtient la différence entre la sortie du premier additionneur et un signal de rétroaction qui est une rétroaction d'une sortie du quantificateur, et donne la différence au filtre de boucle, le filtre de boucle ayant une première bande passante correspondant à la fréquence du premier signal d'entrée et une deuxième bande passante correspondant à la fréquence du deuxième signal d'entrée. Dans les caractéristiques de fréquence du modulateur ΔΣ, un ou plusieurs pôles et/ou un ou plusieurs points zéro sont disposés entre une première bande de prévention de bruit correspondant à la première bande passante et une deuxième bande de prévention de bruit correspondant à la deuxième bande passante.
PCT/JP2018/029746 2017-12-08 2018-08-08 Modulateur δς, émetteur, circuit intégré à semiconducteur et programme informatique WO2019111446A1 (fr)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014133061A1 (fr) * 2013-02-27 2014-09-04 住友電気工業株式会社 Modulateur ∆σ et dispositif de communication
WO2018123250A1 (fr) * 2016-12-28 2018-07-05 住友電気工業株式会社 Modulateur δς, émetteur, circuit intégré à semi-conducteur, procédé de traitement et programme d'ordinateur

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Publication number Priority date Publication date Assignee Title
WO2014133061A1 (fr) * 2013-02-27 2014-09-04 住友電気工業株式会社 Modulateur ∆σ et dispositif de communication
WO2018123250A1 (fr) * 2016-12-28 2018-07-05 住友電気工業株式会社 Modulateur δς, émetteur, circuit intégré à semi-conducteur, procédé de traitement et programme d'ordinateur

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JIQIN HE ET AL.: "Dual-band Transmitters Based on Lowpass and Bandpass Delta-Sigma Modulators, Microwave and Millimeter Wave Technology(ICMMT", 2016 IEEE INTERNATIONAL CONFERENCE ON MICROWAVE AND MILLIMETER WAVE TECHNOLOGY (ICMMT),, June 2016 (2016-06-01), pages 590 - 592, XP033013968 *
SUNGWON CHUNG ET AL.: "Inter-band carrier aggregation digital transmitter architecture with concurrent multi-band delta-sigma modulation using out-of-band noise cancellation", 2015 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM, May 2015 (2015-05-01), pages 1 - 4, XP033181386 *
TAKASHI MAEHATA ET AL.: "Concurrent Dual-band 1-bit Digital Transmitter Using Band-Pass Delta-Sigma Modulator", PROCEEDINGS OF THE 8TH EUROPEAN MICROWAVE INTEGRATED CIRCUITS CONFERENCE, October 2013 (2013-10-01), pages 552 - 555, XP032533950 *

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