Frequency agile multiband transmitter using a radio frequency digital to analog converter
View Patent ↗Embodiments of the claimed subject matter provide a method and apparatus for generating a first radio frequency digital signal and providing the first radio frequency digital signal to a radio frequency digital-to-analog converter operating at a sampling frequency. The output of the radio frequency digital-to-analog converter includes a first carrier signal corresponding to the first radio frequency digital signal and having a first frequency below the sampling frequency and an image of the first carrier signal having a second frequency above the sampling frequency. The output of the radio frequency digital-to-analog converter is filtered to select the image of the first carrier signal for transmission.
1. A method, comprising:
generating a first radio frequency digital signal;
providing the first radio frequency digital signal to a radio frequency digital-to-analog converter operating at a sampling frequency, an output of the radio frequency digital-to-analog converter comprising a first carrier signal corresponding to the first radio frequency digital signal and having a first frequency below the sampling frequency and an image of the first carrier signal having a second frequency above the sampling frequency;
filtering the output of the radio frequency digital-to-analog converter to select the image of the first carrier signal for transmission;
generating a second radio frequency digital signal;
mixing the first radio frequency digital signal with the second radio frequency digital signal;
providing the mixed first radio frequency digital signal and second radio frequency digital signal to the radio frequency digital-to-analog converter, the output of the radio frequency digital-to-analog converter comprising the first carrier signal and a second carrier signal corresponding to the second radio frequency digital signal; and
filtering the output of the radio frequency digital-to-analog converter to select the second carrier signal and the image of the first carrier signal for transmission.
2. The method of claim 1 , wherein filtering the output of the radio frequency digital-to-analog converter comprises blocking the first carrier signal.
3. The method of claim 1 , wherein the second carrier signal comprises an image of a third carrier signal corresponding to the second radio frequency digital signal, the second carrier signal having a third frequency greater than the sampling frequency.
4. The method of claim 1 , wherein the second carrier signal has a third frequency less than half of the sampling frequency.
5. The method of claim 1 , wherein generating the first radio frequency signal comprises modulating an output of a first numerically controlled oscillator operating at the first frequency using a first base band signal.
6. The method of claim 1 , wherein generating the first radio frequency signal comprises modulating an output of a first numerically controlled oscillator operating at the first frequency using a first base band signal and generating the second radio frequency signal comprises modulating an output of a second numerically controlled oscillator operating at the second frequency using a second base band signal.
7. The method of claim 1 , further comprising providing the image of the first carrier signal to a power amplifier.
8. A transceiver, comprising:
a first numerically controlled oscillator configured to modulate a first base band signal at a first frequency to generate a first radio frequency digital signal;
a radio frequency digital-to-analog converter operating at a sampling frequency and configured to receive the first radio frequency digital signal and generate a first carrier signal corresponding to the first radio frequency digital signal and having a first frequency below the sampling frequency and an image of the first carrier signal having a second frequency above the sampling frequency; and
a filter configured to select the image of the first carrier signal for transmission;
a second numerically controlled oscillator configured to modulate a second base band signal at a third frequency to generate a second radio frequency digital signal; and
a mixer configured to mix the first radio frequency digital signal with the second radio frequency digital signal, wherein the radio frequency digital-to-analog converter is configured to receive the mixed first radio frequency digital signal and second radio frequency digital signal, an output of the radio frequency digital-to-analog converter comprises the first carrier signal and a second carrier signal corresponding to the second radio frequency digital signal, and the filter is configured to filter the output of the radio frequency digital-to-analog converter to select the second carrier signal and the image of the first carrier signal for transmission.
9. The transceiver of claim 8 , wherein the filter is configured to block the first carrier signal.
10. A transceiver, comprising:
a first numerically controlled oscillator configured to modulate a first base band signal at a first frequency to generate a first radio frequency digital signal;
a radio frequency digital-to-analog converter operating at a sampling frequency and configured to receive the first radio frequency digital signal and generate a first carrier signal corresponding to the first radio frequency digital signal and having a first frequency below the sampling frequency and an image of the first carrier signal having a second frequency above the sampling frequency; and
a filter configured to select the image of the first carrier signal for transmission;
a second numerically controlled oscillator configured to modulate a second base band signal at a third frequency to generate a second radio frequency digital signal; and
a mixer configured to mix the first radio frequency digital signal with the second radio frequency digital signal, wherein the radio frequency digital-to-analog converter is configured to receive the mixed first radio frequency digital signal and second radio frequency digital signal, an output of the radio frequency digital-to-analog converter comprises the first carrier signal, a second carrier signal corresponding to the second radio frequency digital signal, and an image of the second carrier signal having a fourth frequency greater than the sampling frequency, and the filter is configured to filter the output of the radio frequency digital-to-analog converter to select the image of the second carrier signal and the image of the first carrier signal for transmission.
11. The transceiver of claim 8 , wherein the third frequency is less than half of the sampling frequency.
12. The transceiver of claim 8 , further comprising a power amplifier coupled to the filter.
13. A transceiver, comprising:
a first numerically controlled oscillator configured to modulate a first base band signal at a first frequency to generate a first radio frequency digital signal;
a second numerically controlled oscillator configured to modulate a second base band signal at a second frequency to generate a second radio frequency digital signal;
a mixer configured to mix the first radio frequency digital signal with the second radio frequency digital signal;
a radio frequency digital-to-analog converter operating at a sampling frequency greater than the first and second frequencies and configured to receive the first and second radio frequency digital signals and generate first and second carrier signals corresponding to the first and second radio frequency digital signals, respectively, and an image of at least the first carrier signal having a third frequency above the sampling frequency; and
a filter configured to select the image of the first carrier signal and the second carrier signal for transmission.
14. The transceiver of claim 13 , further comprising a power amplifier coupled to the filter.