Direct compensation of IQ samples for undesired frequency deviation in phase locked loops

1. A transmitter adapted for compensating of undesired frequency deviation effects in a phase locked loop (PLL) coupled with a local oscillator and used in a mobile communication device, the transmitter comprising:

estimation circuitry configured to:

input a phase error between the local oscillator and a reference frequency; and

estimate, based on the phase error, values for parameters that describe a frequency deviation experienced by the phase locked loop (PLL) during transmission of a data sample; and

correction circuitry configured to:

generate a correction term based on the estimated parameters;

combine the correction term with the data sample to generate a compensated data sample; and

provide the compensated data sample for modulation of a carrier wave generated by the local oscillator.

2. The transmitter of claim 1 , wherein the estimation circuitry is configured to estimate a gain (γ) and phase offset (Γ) of the frequency deviation caused by a pulling effect on the local oscillator during transmission of the data sample.

3. The transmitter of claim 1 , wherein the estimation circuitry is configured to estimate a gain (A) and phase offset (θ) of the frequency deviation caused by injection of spurious tones or self-generated spurious tones in one or more points in the PLL.

4. The transmitter of claim 1 , wherein the correction circuitry is configured to:

compute a frequency correction signal based at least on the parameter values such that the frequency correction signal comprises an estimate of the frequency deviation;

filter the frequency correction signal with a filter having a transfer function that models a loop response of the PLL to determine a filtered frequency correction signal;

determine a phase correction signal based at least on the filtered frequency correction signal; and

convert the phase correction signal into the correction term.

5. The transmitter of claim 4 , wherein the correction circuitry comprises a computation unit configured to compute the frequency correction signal as a function of an amplitude of the data sample, a phase of the data sample, an estimated gain determined by the estimation circuitry, and an estimated phase offset determined by the estimation circuitry.

6. The transmitter of claim 4 , wherein the correction circuitry comprises:

a filter component configured to filter the frequency correction signal, wherein the filter component is selected to model a transfer function of the PLL from an injection point to an output of the PLL; and

an accumulator component configured to accumulate the filtered frequency correction signal to create the phase correction signal.

7. The transmitter of claim 4 , wherein the data samples comprise first I and Q components representing the data, further wherein the correction circuitry is configured to convert the phase correction signal into the correction term by converting the phase correction signal into second I and Q components such that the correction term comprises the second I and Q components.

8. A method for compensating of undesired frequency deviation effects in a phase locked loop (PLL) used in a mobile communication device, the method comprising:

inputting a data sample to be communicated;

inputting a phase error between a reference frequency and a carrier wave generated by a local oscillator of a phase locked loop (PLL);

estimating values for parameters, based on the phase error, which describe a frequency deviation experienced by the PLL during transmission of the carrier wave modulated based on the data sample;

generating a correction term based on the estimated parameter values;

combining the correction term with the data sample to generate a compensated data sample; and

providing the compensated data sample for modulation of the carrier wave generated by the local oscillator.

9. The method of claim 8 , comprising:

computing a frequency correction signal based at least on the estimated parameter values, such that the frequency correction signal comprises an estimate of the frequency deviation;

filtering the frequency correction signal with a filter having a transfer function that models a loop response of the PLL to determine a filtered frequency correction signal;

determining a phase correction signal based at least on the filtered frequency correction signal; and

converting the phase correction signal into the correction term.

10. The method of claim 9 , comprising computing the frequency correction signal as a function of an amplitude of the data sample, a phase of the data sample, an estimated gain of a frequency deviation and an estimated phase offset of the frequency deviation.

11. The method of claim 9 , comprising:

filtering the frequency correction signal with a filter component selected to model a transfer function of the PLL from an injection point to an output of the PLL; and

accumulating the filtered frequency correction signal to create the phase correction signal.

12. The method of claim 9 , wherein the data samples comprise first I and Q components representing the data, further comprising converting the phase correction signal into the correction term by converting the phase correction signal into second I and Q components such that the correction term comprises the second I and Q components.

13. The method of claim 8 , comprising estimating a gain (γ) and phase offset (Γ) of the frequency deviation caused by a pulling effect on the local oscillator during transmission of the data sample.

14. The method of claim 8 , comprising estimating a gain (A) and phase offset (θ) of the frequency deviation caused by injection of spurious tones or self-generated spurious tones in one or more points in the PLL.