Wireless transmitter using a widebrand digital-to-analog converter for processing multiple channels in a digital radio-frequency signal
A wireless transmitter processing chain includes digital radio frequency mixing circuitry to generate, in digital form, a representation of a transmit signal including multiple communication channels. From the digital representation, a wideband digital to analog converter creates the analog transmit signal that includes the communication channels. Individual mixers and filters follow, with mixing frequencies tuned to place the communication channels at the desired frequency centers.
1. A system comprising:
a wideband digital-to-analog converter (WDAC) configured to receive a digital radio-frequency (RF) signal, convert a plurality of communication channels in the digital RF signal to a plurality of analog RF channels, and output an analog RF signal comprising the plurality of analog RF channels; and
a plurality of mixers coupled to the WDAC and configured to receive the analog RF signal comprising the plurality of analog RF channels, the plurality of mixers comprising:
a first mixer configured to:
receive a first clock signal; and
place a first analog RF channel among the plurality of analog RF channels in the analog RF signal at a first center frequency using the first clock signal; and
a second mixer configured to:
receive a second clock signal; and
place a second analog RF channel among the plurality of analog RF channels in the analog RF signal at a second center frequency using the second clock signal.
2. The system of claim 1 , wherein the first center frequency and the second center frequency are different center frequencies.
3. The system of claim 1 , wherein the first center frequency and the second center frequency are at a common center frequency.
4. The system of claim 1 , wherein the WDAC is further configured to receive a digital-to-analog converter (DAC) clock signal, and the system further comprising:
circuitry configured to derive the first clock signal and the second clock signal from the DAC clock signal.
5. The system of claim 4 , wherein the circuitry is further configured to generate the first clock signal and the second clock signal by setting clock dividers.
6. The system of claim 1 , further comprising:
circuitry configured to set the first clock signal and the second clock signal statically.
7. The system of claim 1 , wherein the first clock signal and the second clock signal are fixed.
8. The system of claim 1 , wherein the first mixer of the plurality of mixers outputs a first resulting signal on a first transmit output, and the second mixer of the plurality of mixers outputs a second resulting signal on a second transmit output that is a separate transmit output from the first transmit output.
9. The system of claim 1 , wherein the plurality of communication channels are WIFI channels defined under IEEE 802.11 specifications.
10. The system of claim 1 , wherein the first center frequency and the second center frequency are between 5.001 GHz and 5.999 GHz.
11. The system of claim 1 , wherein the plurality of mixers comprise individual hardware mixers individually coupled to separate transmit outputs.
12. A system comprising:
first circuitry comprising a plurality of mixers coupled to a single wideband digital-to-analog converter (WDAC), the first circuitry configured to receive an analog radio-frequency (RF) signal comprising a plurality of communication channels from the single WDAC, wherein each mixer of the plurality of mixers is configured to receive a respective mixer clock signal and output a respective resulting signal on a separate transmit output; and
second circuitry coupled to the first circuitry and comprising a plurality of band-pass filters on respective transmit paths, wherein the plurality of band-pass filters on the respective transmit paths are implemented as identical filters.
13. The system of claim 12 , wherein a channel space of the communication channels is larger than a bandwidth of the band-pass filters.
14. The system of claim 12 , wherein the plurality of mixers move the plurality of communication channels to a common center frequency.
15. The system of claim 12 , wherein the plurality of mixers move the plurality of communication channels to different center frequencies.
16. The system of claim 12 , further comprising:
third circuitry configured to derive the respective mixer clock signal from a digital-to-analog converter (DAC) clock signal.
17. The system of claim 12 , wherein the plurality of communication channels are WIFI channels defined under IEEE 802.11 specifications, and center frequencies of the plurality of communication channels are between 5.001 GHz and 5.999 GHz.
18. A method comprising:
receiving, on a digital transmit input, digital radio-frequency (RF) signal including a plurality of communication channels spaced in frequency;
converting, using a wideband digital-to-analog converter (WDAC), the plurality of communication channels received in the digital RF data to a plurality of analog RF channels in an analog RF signal on an analog transmit output; and
mixing, using a plurality of mixers, each of the plurality of analog RF channels to a respective center frequency on different transmit outputs.
19. The method of claim 18 , wherein the respective center frequency of the each of the plurality of analog RF channels is at a common center frequency.
20. The method of claim 18 , wherein respective center frequencies of the plurality of analog RF channels are at different center frequencies.