Polar modulation apparatus and method using FM modulation
View Patent ↗The present invention relates to a polar modulation apparatus and method, in which an in-phase and a quadrature-phase signal are processed in the analog domain to generate an analog signal corresponding to a derivative of a phase component of said polar-modulated signal. The analog signal is then input to a control input of a controlled oscillator ( 40 ). As an example, the processing may be based on a differentiate-and-multiply algorithm in the analog domain. Thereby, phase and envelope signals are generated in the analog domain and bandwidth enlargement due to the processing of the polar signals and corresponding aliasing can be prevented to obtain a highly accurate polar-modulated output signal.
1. A polar modulation apparatus in which a phase component of an input signal is used for tuning a controlled oscillator and an amplitude component of said input signal is used for modulating an output amplifier, said apparatus comprising:
a frequency modulator configured to receive an in-phase component and a quadrature-phase component of said input signal and configured to process said in-phase and quadrature-phase components in the analog domain to generate an analog signal corresponding to a derivative of said phase component; and
an input configured to input said analog signal to a control input of said control oscillator.
2. An apparatus according to claim 1 , wherein said frequency modulator comprises a differentiating component configured to differentiate said in-phase component and said quadrature-phase component, and a multiplying component configured to multiply the differentiated in-phase component with said quadrature-phase component and to multiply the differentiated quadrature-phase component with said in-phase component.
3. An apparatus according to claim 2 , wherein said frequency modulator comprises a subtractor configured to subtract the output signals of said multiplying component.
4. An apparatus according to claim 2 , wherein said differentiating component and said multiplying component are analog circuits.
5. An apparatus according to claim 2 , wherein said differentiating component comprises an RC network.
6. An apparatus according to claim 1 , wherein said control oscillator is included in a phase locked loop, the control oscillator configured to receive a PLL control signal generated at a phase detector of said phase locked loop.
7. An apparatus according to claim 6 , wherein the phase locked loop comprises an adder configured to add said phase controlled loop control signal to said analog signal.
8. An apparatus according to claim 6 , further comprising a supply component configured to temporarily supply said analog signal to said phase detector when said phase locked loop configuration is in an unlocked state.
9. An apparatus according to claim 1 , wherein said analog signal is applied to a controllable capacitor of said controllable oscillator.
10. An apparatus according to claim 1 , further comprising a squaring component configured to receive said in-phase component and said quadrature-phase component and to generate an envelope signal corresponding to said amplitude component.
11. An apparatus according to claim 10 , wherein said squaring component comprises a non-linear element.
12. An apparatus according to claim 1 , further comprising a coupling component configured to provide an alternate current coupling between said frequency modulator and said input.
13. An apparatus according to claim 1 , further comprising an amplitude processing component configured to multiply the amplitude of said analog signal by a squared inverse of said amplitude component.
14. An apparatus according to claim 1 , wherein said controlled oscillator and said output amplifier are integrated to form a power oscillator.
15. A method of producing a polar-modulated signal, said method comprising the steps of:
providing an in-phase signal and a quadrature-phase signal;
processing said in-phase and quadrature-phase signal in the analog domain to generate an analog signal corresponding to a derivative of a phase component of said polar-modulated signal; and
inputting said analog signal to a control input of a controlled oscillator.
16. A polar modulation apparatus in which a phase component of an input signal is used for tuning a controlled oscillator and an amplitude component of the input signal is used for modulating an output amplifier, the apparatus comprising:
a frequency modulator configured to receive an in-phase component and a quadrature-phase component of the input signal, and to generate an analog signal corresponding to a derivative of the phase component; and
an input configured to input the analog signal to a control input of the control oscillator,
wherein the analog signal is generated by processing the in-phase component and the quadrature-phase component in the analog domain.
17. An apparatus according to claim 16 , wherein the frequency modulator comprises a differentiating component configured to differentiate the in-phase component and the quadrature-phase component, and a multiplying component configured to multiply the differentiated in-phase component with the quadrature-phase component and to multiply the differentiated quadrature-phase component with the in-phase component.
18. An apparatus according to claim 17 , wherein the frequency modulator comprises a subtractor configured to subtract the output signals of the multiplying component.
19. An apparatus according to claim 17 , wherein the differentiating component and the multiplying component are analog circuits.
20. An apparatus according to claim 17 , wherein the differentiating component comprises an RC network.