Signal generation device
A signal generating device includes a digital signal processing unit, M sub DACs of which an analog bandwidth is f B , M being an integer equal to or greater than 2, a broadband analog signal generating unit configured to generate a broadband analog signal that includes a component of a frequency of (M-1)f B or more by using M analog signals output from the M sub DACs. The digital signal processing unit includes components for generating M original divided signals that correspond to signals obtained by dividing a desired output signal into M portions on a frequency axis and down-converting the portions to the baseband, components for generating M folded divided signals by folding back the M original divided signals on the frequency axis, and a 2M×M filter that takes the original divided signals and the folded divided signals as inputs and outputs M composite signals to be transmitted to the M sub DACs. The 2M×M filter can set a response function independently for each of 2M 2 combinations of input and output.
1. A signal generating device comprising:
a digital signal processing unit;
M sub DACs of which an analog bandwidth is f B , M being an integer equal to or greater than 2; and
a broadband analog signal generating unit configured to generate a broadband analog signal that includes a component of a frequency of (M-1)f B or more by using M analog signals output from the M sub DACs, wherein the digital signal processing unit includes means for generating M original divided signals that correspond to signals obtained by dividing a desired output signal into M portions on a frequency axis and down-converting the portions to the baseband, means for generating M folded divided signals by folding back the M original divided signals on the frequency axis, and a 2M×M filter that takes the M original divided signals and the M folded divided signals as inputs and outputs M composite signals to be transmitted to the M sub DACs, and the 2M×M filter is capable of setting a response function independently for each of 2M 2 combinations of input and output,
wherein the broadband analog signal generating unit is any of an analog multiplexer that outputs two input signals while switching the input signals at high speed at a constant frequency, a circuit in which the analog multiplexer is connected in the form of a multistage tree, a circuit in which at least M-1 input signals of M input signals are up-converted in frequencies by using a mixer, and then combined and output, and a circuit in which the analog multiplexer and the mixer are used in combination.
2. The signal generating device according to claim 1 , wherein, when R kp (f) represents a frequency response of the broadband analog signal generating unit, the response function G mq (f) of the 2M×M filter independently set for each of 2M 2 combinations of input and output is determined by the following expression
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where the tilde symbol ˜ represents a folding operation in which an original function is folded back with f B /2 being the center of the fold to take the complex conjugate, f B being the analog bandwidth of the sub DACs.
3. The signal generating device according to claim 2 , wherein the digital signal processing unit includes at least either a main nonlinear filter that is connected to an input side of the means for generating the original divided signals or M sub nonlinear filters that are respectively connected to M outputs of the 2M×M filter.
4. A signal generating device comprising:
a digital signal processing unit;
M sub DACs of which an analog bandwidth is f B , M being an integer equal to or greater than 2; and
a broadband analog signal generating unit configured to generate a broadband analog signal that includes a component of a frequency of (M-1)f B or more by using M analog signals output from the M sub DACs, wherein the digital signal processing unit includes means for generating M original divided signals that correspond to signals obtained by dividing a desired output signal into M portions on a frequency axis and down-converting the portions to the baseband, means for generating M folded divided signals by folding back the M original divided signals on the frequency axis, and a 2M×M filter that takes the M original divided signals and the M folded divided signals as inputs and outputs M composite signals to be transmitted to the M sub DACs, and the 2M×M filter is capable of setting a response function independently for each of 2M 2 combinations of input and output,
wherein, when Rk p (f) represents a frequency response of the broadband analog signal generating unit, the response function G mq (f) of the 2M×M filter independently set for each of 2M 2 combinations of input and output is determined by the following expression
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where the tilde symbol ˜ represents a folding operation in which an original function is folded back with f B /2 being the center of the fold to take the complex conjugate, f B being the analog bandwidth of the sub DACs.
5. The signal generating device according to claim 4 , wherein the broadband analog signal generating unit is an IQ modulator circuit that is constituted by two mixers, a combiner, and a 90-degree phase shifter.
6. The signal generating device according to claim 5 , wherein the digital signal processing unit includes at least either a main nonlinear filter that is connected to an input side of the means for generating the original divided signals or M sub nonlinear filters that are respectively connected to M outputs of the 2M×M filter.
7. The signal generating device according to claim 4 , wherein the digital signal processing unit includes at least either a main nonlinear filter that is connected to an input side of the means for generating the original divided signals or M sub nonlinear filters that are respectively connected to M outputs of the 2M×M filter.
8. A signal generating device comprising:
a digital signal processing unit;
M sub DACs of which an analog bandwidth is f B , M being an integer equal to or greater than 2; and
a broadband analog signal generating unit configured to generate a broadband analog signal that includes a component of a frequency of (M-1)f B or more by using M analog signals output from the M sub DACs, wherein the digital signal processing unit includes means for generating M original divided signals that correspond to signals obtained by dividing a desired output signal into M portions on a frequency axis and down-converting the portions to the baseband, means for generating M folded divided signals by folding back the M original divided signals on the frequency axis, and a 2M×M filter that takes the M original divided signals and the M folded divided signals as inputs and outputs M composite signals to be transmitted to the M sub DACs, and the 2M×M filter is capable of setting a response function independently for each of 2M 2 combinations of input and output,
wherein the broadband analog signal generating unit is any of an analog multiplexer that outputs two input signals while switching the input signals at high speed at a constant frequency, a circuit in which the analog multiplexer is connected in the form of a multistage tree, a circuit in which at least M-1 input signals of M input signals are up-converted in frequencies by using a mixer, and then combined and output, and a circuit in which the analog multiplexer and the mixer are used in combination,
wherein the digital signal processing unit includes at least either a main nonlinear filter that is connected to an input side of the means for generating the original divided signals or M sub nonlinear filters that are respectively connected to M outputs of the 2M×M filter.