Polar modulator with signed amplitude reducing phase transitions
View Patent ↗A polar modulator including a signal converter configured to provide a phase signal and an amplitude signal based on at least one received signal is disclosed. A digital-to-analog converter is coupled to the signal converter, the digital-to-analog converter configured to receive an augmented signal, wherein a polarity of the augmented signal is selected to minimize an absolute phase change for sequential signals. A signal mixer is coupled to the digital-to-analog converter to receive an analog signal generated from the augmented signal.
1. A polar modulator comprising:
a signal converter configured to provide a phase signal and an amplitude signal based on at least one received signal;
a digital-to-analog converter coupled to the signal converter, the digital-to-analog converter configured to receive an augmented signal, wherein a polarity of the augmented signal is selected to minimize an absolute phase change for sequential signals; and
a radio frequency mixer coupled to the digital-to-analog converter to receive an analog signal generated from the augmented signal.
2. The polar modulator of claim 1 , wherein the signal converter is configured to provide the augmented signal.
3. The polar modulator of claim 1 , wherein the signal converter includes a Cartesian-to-polar converter.
4. The polar modulator of claim 3 , wherein the Cartesian-to-polar converter is configured to receive a signal from an I/Q modulator.
5. The polar modulator of claim 1 , wherein the augmented signal is selected to limit the absolute phase change to a maximum of about half the phase signal.
6. The polar modulator of claim 1 , wherein the signal converter includes an I/Q modulator.
7. The polar modulator of claim 1 , wherein the amplitude signal includes the real part of a complex signal received from an I/Q modulator.
8. The polar modulator of claim 7 , wherein the amplitude signal includes the imaginary part of a complex signal received from an I/Q modulator.
9. The polar modulator of claim 1 , wherein the absolute phase change is from about 0 to about π/2.
10. The polar modulator of claim 1 , wherein the at least one of the signal converter and a decision circuit is configured to provide an output signal having the form s(n)·R(n), wherein s(n) is either −1 or 1, and wherein R(n) is an amplitude portion of a Cartesian representation of a signal received from an I/Q modulator.
11. A method comprising:
coupling data signals to a converter, the converter comprising a Cartesian-to-polar converter;
forming augmented signals to limit an absolute phase change of sequential signal using the data signals, the augmented signals based on a phase of the data signals; and
transmitting the augmented signal to a digital-to-analog converter.
12. The method of claim 11 , wherein forming includes forming augmented signals having an amplitude of ·R(n) or +R(n), where R(n) is the real part of the data signals.
13. The method of claim 11 , wherein forming includes forming to limit the absolute phase change from about −π/2 to about π/2.
14. The method of claim 11 , wherein forming includes forming augmented signals based on a phase ranging from −π to about π.