Direct digital conversion tuner and method for using same
View Patent ↗A direct sampling tuner includes a low noise amplifier and an optional dynamically configurable band pass filter coupled to the low noise amplifier. The optional filter is configured to pass a selected band of channels. The tuner further includes a relatively high accuracy, multi-bit analog-to-digital converter (“ADC”) coupled to the LNA or to the optional dynamically configurable band pass filter. The ADC operates at greater than about twice a frequency of a sampled signal. The ADC directly samples the spectrum of the selected channels at the Nyquist frequency, thus avoiding image problems presented by conventional tuners.
1. A direct sampling tuner for receiving an RF signal having multiple channels, comprising:
a low noise amplifier arranged at a front end of the tuner and configured to be a first element to receive the RF signal and then to amplify the RF signal;
a dynamically configurable band pass filter coupled to the low noise amplifier, and configured to pass a selected band of the multiple channels of the amplified RF signal; and
a multi-bit analog-to-digital converter coupled to the dynamically configurable band pass filter, wherein the analog-to-digital converter operates at greater than twice a frequency of the selected band of the multiple channels of the amplified RF signal.
2. The tuner according to claim 1 , wherein the analog-to-digital converter comprises between an 8 to 12 bit analog-to-digital converter.
3. The tuner according to claim 1 , further comprising a noise shaping module coupled to the analog-to-digital converter.
4. The tuner according to claim 3 , wherein the analog-to-digital converter comprises between an 8 to 12 bit analog-to-digital converter.
5. The tuner according to claim 3 , further comprising a digital signal processor coupled to the noise shaping module.
6. The tuner according to claim 1 , wherein the analog-to-digital converter operates at greater than 1 GHz.
7. The tuner according to claim 1 , wherein the analog-to-digital converter comprises one of a flash or pipeline analog-to-digital converter.
8. The tuner according to claim 1 , wherein the analog-to-digital converter comprises a sample and hold module and 2 n comparators, wherein n equals a number of bits in the sample and hold module.
9. The tuner according to claim 1 , wherein the analog-to-digital converter comprises a multiple-stage pipeline analog-to-digital converter wherein each stage of the multiple-stage pipeline analog-to-digital converter comprises one or more bits.
10. The tuner according to claim 1 , wherein the analog-to-digital converter comprises an open loop analog-to-digital converter.
11. The tuner according to claim 1 , wherein the low noise amplifier and the dynamically configurable band pass filter are implemented on a single integrated circuit.
12. The tuner according to claim 1 , wherein the tuner is incorporated within a cable modem.
13. The tuner according to claim 1 , wherein the tuner is incorporated within a cable set top box.
14. The tuner according to claim 1 , wherein the low noise amplifier comprises an autonomous gain control configured to keep an output of the low noise amplifier at a fixed voltage level.
15. A method for tuning an RF signal having multiple channels using a direct sampling tuner, comprising:
initially receiving the RF signal at a low noise amplifier arranged at a front end of the tuner;
amplifying the multiple channels of the RF signal using the amplifier;
filtering, using a digitally selectable bank of filters, all but a sub-set of channels from the amplified multiple channels;
converting the sub-set of channels to a multi-bit digital signal, wherein said converting is performed at a sample rate that is greater than twice a frequency of a highest frequency in the sub-set of channels; and
digitally processing the multi-bit digital signal to obtain information from the sub-set of channels.
16. The method according to claim 15 , wherein said converting comprises converting the sub-set of channels to between an 8 to 10 bit digital signal.
17. The method according to claim 15 , further comprising noise shaping the multi-bit digital signal.
18. The method according to claim 17 , wherein said converting comprises converting the sub-set of channels to between an 8 to 10 bit digital signal.
19. The method according to claim 15 , wherein said converting is performed at or above 1 GHz.
20. The method according to claim 15 , wherein said converting comprises interleaving.
21. The method according to claim 15 , wherein the digital processing comprises one or more of channel filtering, equalization, demodulation, decimation, and/or gain control.
22. A direct sampling tuner for receiving an RF signal having multiple channels, comprising:
a low noise amplifier arranged at a front end of the tuner and configured to be a first element to receive the RF signal and then to amplify the RF signal;
a filter configured to receive the amplified RF signal having the multiple channels;
a multi-bit analog-to-digital converter coupled to the filter, wherein the analog-to-digital converter operates at greater than twice a frequency of a selected band of the multiple channels of the amplified RF signal; and
a digital signal processor that is used to demodulate the selected band of the multiple channels of the amplified RF signal.
23. A method for tuning an RF signal having multiple channels using a direct sampling tuner, comprising:
initially receiving the RF signal at an amplifier arranged at a front end of the tuner;
amplifying the multiple channels of the RF signal using the amplifier;
filtering the amplified multiple channels;
converting the filtered multiple channels to a multi-bit digital signal, wherein said converting is performed at a sample rate that is greater than twice a frequency of a highest frequency in the filtered multiple channels;
noise shaping the multi-bit digital signal; and
demodulating the noise shaped multi-bit digital signal to obtain information from one or more of the multiple channels.
24. A direct sampling tuner for receiving an RF signal having multiple channels, comprising:
a low noise amplifier arranged at a front end of the tuner and configured to be a first element to receive the RF signal and then to amplify the RF signal;
a dynamically configurable band pass filter coupled to the low noise amplifier, and configured to pass a selected band of the multiple channels of the amplified RF signal; and
a multi-bit analog-to-digital converter coupled to the dynamically configurable band pass filter, wherein the analog-to-digital converter operates at less than twice a carrier frequency of the selected band of the multiple channels, but at greater than twice a frequency of an information modulated on the selected band of the multiple channels.