Calibration techniques for non-linear devices
View Patent ↗An apparatus may include a non-linear module, a control module, and a calibration module. The non-linear module produces an output signal from an input signal. The control module selects, upon an occurrence of a calibration condition, a calibration operation from two or more calibration operations. Each of the two or more calibration operations may generate one or more correction values for the non-linear module. Further, each of the calibration operations produces the input signal from a pre-input signal. This selected calibration operation is performed by the calibration module. The two or more calibration operations include a first calibration operation and a second calibration operation. The first calibration operation produces the input signal from the pre-input signal according to a predictive technique. The second calibration operation produces the input signal from the pre-input signal according to a non-predictive technique.
1. An apparatus, comprising:
a non-linear module configured to produce an output signal from an input signal;
a control module configured to select, upon an occurrence of a calibration condition, a calibration operation from two or more calibration operations;
a calibration module configured to perform the selected calibration operation, said selected calibration operation comprising
(a) predicting or extrapolating at least one non-linear characteristic of said non-linear module based on said output signal and a reference signal,
(b) based on said predicting or extrapolating, generating one or more correction values for use during subsequent pre-distortion operations to compensate for said non-linear characteristic of the non-linear module,
(c) performing said predicting or extrapolating using predicative correction operations to produce the input signal from a pre-input signal when said calibration condition comprises a power ramp-up or a power ramp-down of said pre-input signal, said predictive correction operations comprising changing values of said pre-input signal based on said predicted or extrapolated non-linear characteristic of said non-linear module, and
(d) performing said predicting or extrapolating while by-passing said predictive correction operations when said calibration condition comprises a steady state of said pre-input signal during which changes to a parameter selected from the group consisting of a power level and a frequency are less than a predetermined threshold associated with said parameter.
2. The apparatus of claim 1 , wherein the non-linear module includes a power amplifier.
3. The apparatus of claim 1 , further comprising a storage medium to store the one or more correction values.
4. The apparatus of claim 1 , further comprising a pre-distortion module to generate the input signal from the pre-input signal based on the one or more correction values.
5. The apparatus of claim 1 , wherein the calibration condition is a power level change when the pre-input signal is conveying data.
6. The apparatus of claim 1 , wherein the pre-input signal is a wideband code division multiple access (WCDMA) signal.
7. The apparatus of claim 1 , wherein the pre-input signal is a time division multiple access (TDMA) signal.
8. A method, comprising:
selecting, upon an occurrence of a calibration condition, a calibration operation from two or more calibration operations; and
performing the selected calibration operation for a non-linear module that produces an output signal from an input signal, said selected calibration operation comprising:
(a) predicting or extrapolating at least one non-linear characteristic of said non-linear module based on said output signal and a reference signal,
(b) based on said predicting or extrapolating, generating one or more correction values for use during subsequent pre-distortion operation to compensate for said non-linear characteristic of the non-linear module,
(c) performing said predicting or extrapolating using predicting correction operations to produce the input signal from a pre-input signal when said calibration condition comprises a power ramp-up or a power ramp-down of said pre-input signal, said predictive correction operations comprising changing values of said pre-input signal based on said predicted or extrapolated non-linear characteristic of said non-linear module, and
(d) performing said predicting or extrapolating while by-passing said predictive correction operations when said calibration condition comprises a steady state of said pre-input signal during which changes to a parameter selected from the group consisting of a power level and a frequency are less than a predetermined threshold associated with said parameter.
9. The method of claim 8 , wherein the selected calibration operation stores the one or more correction values in a storage medium.
10. The method of claim 8 , further comprising bypassing said predictive correction operations when the calibration condition is a power level change when the pre-input signal conveys data.
11. The method of claim 10 , wherein the power level change is in accordance with a power control protocol.
12. The method of claim 8 , wherein the calibration condition comprises a change in operating temperature.
13. An apparatus, comprising:
a transmit module configured to generate an output signal; and
an antenna to wirelessly transmit the output signal;
wherein the transmit module includes:
a non-linear module configured to produce an output signal from an input signal;
a control module configured to select, upon an occurrence of a calibration condition, a calibration operation from two or more calibration operations;
a calibration module configured to perform the selected calibration operation, said selected calibration operation comprising
(a) predicting or extrapolating at least one non-linear characteristic of said non-linear module based on said output signal and a reference signal,
(b) based on said predicting or extrapolating, generating one or more correction values for use during subsequent pre-distortion operations to compensate for said non-linear characteristic of the non-linear module,
(c) performing said predicting or extrapolating using predictive correction operations to produce the input signal from a pre-input signal exclusively when said calibration condition comprises a power ramp-up or a power ramp-down of said pre-input signal, said predictive correction operations comprising changing values of said pre-input signal based on said predicted or extrapolated non-linear characteristic of said non-linear module, and
(d) performing said predicting or extrapolating while by-passing said predictive correction operations when said calibration condition comprises a steady state of said pre-input signal during which changes to a parameter selected from the group consisting of a power level and a frequency are less than a predetermined threshold associated with said parameter.
14. The apparatus of claim 13 , further comprising a storage medium to store the one or more correction values.
15. The apparatus of claim 13 , further comprising a receive module to receive signals from the antenna.