Digital analog dither adjustment
A method and system for data conversion includes an analog noise generator to generate a random, non-deterministic, analog noise signal. An adder adds the analog noise signal to an analog RF signal to produce a dithered analog signal. A first quantizer converts the analog noise signal to digital to produce a digital noise signal. A second quantizer converts the dithered analog signal to a digital equivalent signal. A digital dither adjustment module removes amplitude measurements of the digital noise signal from the digital equivalent signal to obtain a linearized digital representation of the analog RF signal.
1. A data conversion system, comprising:
an analog noise generator adapted to generate a random, non-deterministic, analog noise signal;
an adder adapted to add the analog noise signal to an analog RF signal to produce a dithered analog signal;
a first quantizer adapted to convert the analog noise signal to digital to produce a digital noise signal;
gain control circuity for controlling the gain of the system such that the analog noise signal contained within the dithered analog signal toggles among least significant bits of a second quantizer, the second quantizer adapted to convert the dithered analog signal to a digital equivalent signal; and
a digital dither adjustment module adapted to remove amplitude measurements of the digital noise signal from the digital equivalent signal to obtain a linearized digital representation of the analog RF signal.
2. The data conversion system of claim 1 , wherein the analog noise generator comprises a thermal noise diode.
3. The data conversion system of claim 1 , wherein the analog noise generator comprises a uniform analog noise generator.
4. The data conversion system of claim 1 , wherein the first quantizer has a lower bit resolution than the second quantizer.
5. The data conversion system of claim 1 , wherein the first quantizer has a bit resolution of four or fewer.
6. The data conversion system of claim 1 , further comprising a frequency conversion circuit that includes a local oscillator adapted to frequency convert a signal received from an antenna to obtain the analog RF signal.
7. The data conversion system of claim 1 , wherein the digital dither adjustment module is further adapted to remove the amplitude measurements of the digital noise signal from the digital equivalent signal by subtracting the amplitude measurements from the digital noise signal.
8. The data conversion system of claim 1 , further comprising logarithmic amplifying circuitry adapted to amplify the analog noise signal prior to conversion by the first quantizer.
9. The data conversion system of claim 1 , wherein the first quantizer comprises a step-wise linear quantizer or a non-uniform quantizer having larger quantization errors at its higher most significant bits.
10. A method of linearizing a quantizer, comprising:
generating with an analog noise generator a random, non-deterministic, analog noise signal;
adding the noise signal to an analog RF signal to produce a dithered analog signal;
controlling the gain of the system such that the analog noise signal contained within the dithered analog signal toggles among least significant bits of a second quantizer;
converting the analog noise signal to a digital noise signal with a first quantizer;
converting the dithered analog signal to a digital equivalent signal with the second quantizer; and
removing measured amplitudes of the digital noise signal from the digital equivalent signal to obtain a linearized digital representation of the analog RF signal.
11. The method of claim 10 , wherein the analog noise generator comprises a thermal noise diode.
12. The method of claim 10 , wherein the analog noise generator comprises a uniform analog noise generator.
13. The method of claim 10 , wherein the first quantizer has a lower bit resolution than the second quantizer.
14. The method of claim 10 , wherein the first quantizer has a bit resolution of four or fewer.
15. The method of claim 10 , further comprising a frequency conversion circuit that includes a local oscillator operational to frequency convert a signal received from an antenna to obtain the analog RF signal.
16. The method of claim 10 , wherein removing measured amplitudes includes subtracting the measured amplitudes of the digital noise signal from the digital equivalent signal.
17. The method of claim 10 , further comprising amplifying with logarithmic amplifying circuitry the analog noise signal prior to converting by the first quantizer.
18. The method of claim 10 , wherein the first quantizer comprises a step-wise linear quantizer or a non-uniform quantizer having larger quantization errors at its higher most significant bits.