Direct digital conversion tuner
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 rate, thus avoiding image problems presented by conventional tuners.
1. A tuner, comprising:
an amplifier arranged at a front end of the tuner and configured to be a first element of the tuner to receive and amplify a radio frequency (RF) signal;
a filter directly connected to the amplifier and configured to receive the amplified RF signal and pass a selected band of the amplified RF signal;
a converter coupled to the filter and configured to receive the selected band of the amplified RF signal; and
a digital signal processor coupled to the converter.
2. The tuner of claim 1 , wherein the digital signal processor is configured to demodulate the selected band of the amplified RF signal.
3. The tuner of claim 1 , wherein the digital signal processor is configured to perform at least one of channel filtering, equalization, decimation, and gain control.
4. The tuner of claim 1 , wherein the filter comprises a dynamically configurable band pass filter.
5. The tuner of claim 1 , wherein the amplifier comprises a low noise amplifier.
6. The tuner of claim 1 , wherein the converter comprises an analog-to-digital converter.
7. The tuner of claim 6 , wherein the analog-to-digital converter operates at frequencies greater than 1 GHz.
8. The tuner of claim 6 , wherein the analog-to-digital converter comprises one of a flash analog-to-digital converter, a pipeline analog-to-digital converter, an open loop analog-to-digital converter, between an 8 to 12 bit analog-to-digital converter, a direct sampling analog-to-digital converter, an interleaved analog-to-digital converter, or 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.
9. The tuner of claim 6 , 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.
10. The tuner according to claim 1 , wherein the converter operates at greater than twice a frequency of the selected hand of the amplified RF signal.
11. The tuner according to claim 1 , wherein the converter operates at less than twice a carrier frequency of the selected band, but at greater than twice a frequency of information modulated on the selected band.
12. The tuner of claim 1 , further comprising a noise shaping module.
13. The tuner of claim 12 , wherein the noise shaping module is coupled between the converter and the digital signal processor.
14. The tuner of claim 12 , wherein the noise shaping module is incorporated within the digital signal processor.
15. The tuner of claim 12 , wherein the noise shaping module includes one or more low bit samplers.
16. The tuner of claim 1 , wherein the amplifier and the filter are implemented on a single integrated circuit.
17. The tuner of claim 1 , wherein the amplifier comprises an autonomous gain control configured to keep an output of the amplifier at a fixed voltage level.
18. The tuner of claim 1 , wherein the amplifier is configured to amplify the RF signal such that the RF signal fills codes in the converter.
19. The tuner of claim 1 , wherein the filter includes a selectable bank of filters, each having a different pass band.