Digital modulator, digital modulating method, digital transceiver system, and testing apparatus

1. A digital modulator, comprising:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave; and

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave, the delay amount setting section including an exclusive OR gate that receives two inputs, one input being a value of a 1-bit portion of N-bit transmission data for setting the delay amount, and the other input being an output of the carrier wave output section or the variable delay section.

2. The digital modulator according to claim 1 , wherein

the variable delay section includes a multi-stage delay buffer circuit in which delay buffers that delay an input signal by a unit shift amount are connected in a cascade connection,

the multi-stage delay buffer circuit receives the carrier wave at a first-stage delay buffer as input,

the delay amount setting section includes a multiplexer that selects either an output from the carrier wave output section or an output from each stage of the multi-stage delay buffer circuit, based on the transmission data, and

said other input of the exclusive OR gate is the output of the multiplexer.

3. The digital modulator according to claim 2 , wherein

the multi-stage delay buffer circuit includes M−1 stages of delay buffers in the cascade connection, and

each delay buffer delays the input signal by an amount obtained by dividing a cycle of the carrier wave by M.

4. The digital modulator according to claim 2 , wherein

the multiplexer selects the output according to a value of N−1 bits obtained by removing the 1-bit portion from the N-bit transmission data.

5. The digital modulator according to claim 4 , wherein,

the multi-stage delay buffer circuit includes 2 N-1 −1 stages of delay buffers in the cascade connection, and

each delay buffer delays the input signal by an amount obtained by dividing a cycle of the carrier wave by 2 N .

6. The digital modulator according to claim 1 , further comprising an amplitude modulating section that modulates amplitude of the carrier wave delayed by the variable delay section according to the transmission data.

7. The digital modulator according to claim 6 , further comprising an encoder that encodes the transmission data with delay control data for controlling the delay amount set by the delay amount setting section and amplitude control data for controlling the amplitude modulated by the amplitude modulating section, wherein

the delay amount setting section sets the delay amount of the carrier wave based on the delay control data encoded by the encoder, and

the amplitude modulating section modulates the amplitude of the carrier wave based on the amplitude control data encoded by the encoder.

8. The digital modulator according to claim 1 , wherein

the variable delay section includes a multi-stage delay buffer circuit including a plurality of delay sections connected in a cascade connection,

each delay section includes a delay buffer that delays an input signal by any amount that is less than or equal to a cycle of the carrier wave and a bypass circuit that bypasses the delay buffer,

the multi-stage delay buffer circuit receives the carrier wave at a first-stage delay section as input, and

the delay amount setting section sets a delay amount of the carrier wave by selecting either the delay buffer or the bypass circuit in each delay section, based on the transmission data being transmitted.

9. The digital modulator according to claim 8 , wherein

the multi-stage delay buffer circuit includes L−1 stages of delay sections in the cascade connection,

the delay buffers in the delay sections at the L−1 stages delay the input signal by a period obtained by dividing the cycle of the carrier wave by 2 2 , 2 3 , . . . 2 L , respectively,

said other input of the exclusive OR gate is an output of the multi-stage delay buffer circuit, and

the delay amount setting section sets the delay amount of the carrier wave by selecting either the delay buffer or the bypass circuit in each delay section, based on a value of N−1 bits obtained by removing the 1-bit portion from the N-bit transmission data.

10. The digital modulator according to claim 1 , further comprising:

a delay lock loop that includes a phase difference output section that receives the carrier wave output by the carrier wave output section and a delayed wave having the same phase as the carrier wave via the variable delay section, and outputs a voltage according to a phase difference between the carrier wave and the delayed wave, wherein

the delay lock loop supplies the voltage output by the phase difference output section to the delay buffers in the variable delay section to reset the delay amount of the carrier wave delayed by the variable delay section.

11. A digital modulator, comprising:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave; and

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave, wherein

the variable delay section includes a multi-stage delay buffer circuit including a plurality of delay sections connected in a cascade connection,

each delay section includes a delay buffer that delays an input signal by any amount that is less than or equal to a cycle of the carrier wave and a bypass circuit that bypasses the delay buffer,

the multi-stage delay buffer circuit receives the carrier wave at a first-stage delay section as input, and

the delay amount setting section sets a delay amount of the carrier wave by selecting either the delay buffer or the bypass circuit in each delay section, based on the transmission data being transmitted.

12. The digital modulator according to claim 11 , wherein

the multi-stage delay buffer circuit includes L stages of delay sections in the cascade connection, and

the delay buffers in the delay sections at the L stages delay the input signal by a period obtained by dividing the cycle of the carrier wave by 2 1 , 2 2 , 2 3 , . . . , 2 L , respectively.

13. A digital modulator, comprising:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave;

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave; and

a delay lock loop that includes a phase difference output section that receives the carrier wave output by the carrier wave output section and a delayed wave having the same phase as the carrier wave via the variable delay section, and outputs a voltage according to a phase difference between the carrier wave and the delayed wave, wherein

the delay lock loop supplies the voltage output by the phase difference output section to the delay buffers in the variable delay section to reset the delay amount of the carrier wave delayed by the variable delay section.

14. A digital modulator, comprising:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave;

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave;

an amplitude modulating section that modulates amplitude of the carrier wave delayed by the variable delay section according to the transmission data; and

an encoder that encodes the transmission data with delay control data for controlling the delay amount set by the delay amount setting section and amplitude control data for controlling the amplitude modulated by the amplitude modulating section, wherein

the delay amount setting section sets the delay amount of the carrier wave based on the delay control data encoded by the encoder, and

the amplitude modulating section modulates the amplitude of the carrier wave based on the amplitude control data encoded by the encoder.

15. A digital modulation method, comprising the steps of:

outputting a carrier wave;

delaying the carrier wave;

setting an amount by which the carrier wave is delayed at the delaying step based on transmission data being transmitted by the carrier wave;

receiving, by an exclusive OR gate, two inputs, one input being a value of a 1-bit portion of N-bit transmission data for setting the delay amount, and the other input being the carrier wave or the delayed carrier wave.

16. A digital transceiver system, comprising:

a digital modulator that includes:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave output by the carrier wave output section;

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave, the delay amount setting section including an exclusive OR gate that receives two inputs, one input being a value of a 1-bit portion of N-bit transmission data for setting the delay amount, and the other input being an output of the carrier wave output section or the variable delay section; and

a demodulator that includes:

a reference wave output section that outputs a reference wave identical to the carrier wave;

a phase detecting section that outputs a voltage corresponding to a phase difference between the delayed carrier wave and the reference wave; and

an analog-to-digital converter that converts the voltage output by the phase detecting section into the transmission data.

17. A test apparatus, comprising a digital modulator that includes:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave; and

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave, the delay amount setting section including an exclusive OR gate that receives two inputs, one input being a value of a 1-bit portion of N-bit transmission data for setting the delay amount, and the other input being an output of the carrier wave output section or the variable delay section, wherein

the test apparatus tests a device under test by supplying the device under test with a modulated signal output by the digital modulator.

18. The test apparatus according to claim 17 , further comprising a variable phase section that modulates a timing of a test signal supplied to the device under test, wherein the variable delay section of the digital modulator uses the variable phase section.

19. A digital modulation method, comprising the steps of:

outputting a carrier wave;

delaying the carrier wave by a multi-stage delay buffer circuit including L stages of delay sections connected in a cascade connection, each of the delay sections including a delay buffer that delays an input signal and a bypass circuit that bypasses the delay buffer, the carrier wave being received at a first-stage delay section as input; and

setting an amount by which the carrier wave is delayed at the delaying step by selecting either the delay buffer or the bypass circuit in each delay section, based on transmission data being transmitted by the carrier wave, wherein

the delay buffers in the delay sections at the L stages delay the input signal by a period obtained by dividing the cycle of the carrier wave by 2 1 , 2 2 , 2 3 , . . . , 2 L , respectively.

20. A digital transceiver system, comprising:

a digital modulator that includes:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave output by the carrier wave output section;

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave; and

a demodulator that includes:

a reference wave output section that outputs a reference wave identical to the carrier wave;

a phase detecting section that outputs a voltage corresponding to a phase difference between the delayed carrier wave and the reference wave; and

an analog-to-digital converter that converts the voltage output by the phase detecting section into the transmission data, wherein

the variable delay section includes a multi-stage delay buffer circuit including L stages of delay sections connected in a cascade connection,

each delay section includes a delay buffer that delays an input signal and a bypass circuit that bypasses the delay buffer,

the multi-stage delay buffer circuit receives the carrier wave at a first-stage delay section as input,

the delay amount setting section sets a delay amount of the carrier wave by selecting either the delay buffer or the bypass circuit in each delay section, based on the transmission data being transmitted, and

the delay buffers in the delay sections at the L stages delay the input signal by a period obtained by dividing the cycle of the carrier wave by 2 1 , 2 2 , 2 3 , . . . , 2 L , respectively.

21. A test apparatus, comprising a digital modulator that includes:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave; and

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave, wherein

the variable delay section includes a multi-stage delay buffer circuit including L stages of delay sections connected in a cascade connection,

each delay section includes a delay buffer that delays an input signal and a bypass circuit that bypasses the delay buffer,

the multi-stage delay buffer circuit receives the carrier wave at a first-stage delay section as input,

the delay amount setting section sets a delay amount of the carrier wave by selecting either the delay buffer or the bypass circuit in each delay section, based on the transmission data being transmitted,

the delay buffers in the delay sections at the L stages delay the input signal by a period obtained by dividing the cycle of the carrier wave by 2 1 , 2 2 , 2 3 , . . . , 2 L , respectively, and

the test apparatus tests a device under test by supplying the device under test with a modulated signal output by the digital modulator.

22. A digital modulation method, comprising the steps of:

outputting a carrier wave;

delaying the carrier wave;

setting an amount by which the carrier wave is delayed at the delaying step based on transmission data being transmitted by the carrier wave;

modulating amplitude of the delayed carrier wave according to the transmission data; and

encoding the transmission data with delay control data for controlling the amount by which the carrier wave is delayed at the delaying step and amplitude control data for controlling the amplitude modulated at the modulating step, wherein

the delay amount of the carrier wave is set based on the encoded delay control data, and

the amplitude of the carrier wave is modulated based on the encoded amplitude control data.

23. A digital transceiver system, comprising:

a digital modulator that includes:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave output by the carrier wave output section;

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave;

an amplitude modulating section that modulates amplitude of the carrier wave delayed by the variable delay section according to the transmission data;

an encoder that encodes the transmission data with delay control data for controlling the delay amount set by the delay amount setting section and amplitude control data for controlling the amplitude modulated by the amplitude modulating section; and

a demodulator that includes:

a reference wave output section that outputs a reference wave identical to the carrier wave;

a phase detecting section that outputs a voltage corresponding to a phase difference between the delayed carrier wave and the reference wave; and

an analog-to-digital converter that converts the voltage output by the phase detecting section into the transmission data, wherein

the delay amount setting section sets the delay amount of the carrier wave based on the delay control data encoded by the encoder, and

the amplitude modulating section modulates the amplitude of the carrier wave based on the amplitude control data encoded by the encoder.

24. A test apparatus, comprising a digital modulator that includes:

a carrier wave output section that outputs a carrier wave;

a variable delay section that delays the carrier wave;

a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave;

an amplitude modulating section that modulates amplitude of the carrier wave delayed by the variable delay section according to the transmission data; and

an encoder that encodes the transmission data with delay control data for controlling the delay amount set by the delay amount setting section and amplitude control data for controlling the amplitude modulated by the amplitude modulating section, wherein

the delay amount setting section sets the delay amount of the carrier wave based on the delay control data encoded by the encoder,

the amplitude modulating section modulates the amplitude of the carrier wave based on the amplitude control data encoded by the encoder, and

the test apparatus tests a device under test by supplying the device under test with a modulated signal output by the digital modulator.