Joint adaptive bias point adjustment and digital pre-distortion for power amplifier

A transmitter circuit, comprising:

• one or more transmission chain elements configured to receive an input signal and to generate an output signal;
• a figure of merit measurement element configured to receive information about the output signal from a feedback loop, extending from the one or more transmission chain elements to the figure of merit measurement element, and to determine a measured figure of merit of the output signal;
• an adaptive biasing element configured to adaptively bias the one or more transmission chain elements to iteratively adjusting a current consumption of the one or more transmission chain elements;
• and
• a pre-distortion element located upstream of the one or more transmission chain elements and configured to generate a distorted input signal to account for non-linearities introduced into the output signal during the adaptive biasing,
• wherein the measured figure of merit is evaluated against a predetermined target range that defines a range of actual merit,
• wherein if the measured figure of merit indicates that the actual merit is better than that defined by the predetermined target range, the adaptive biasing element is configured to reduce the current consumption and the actual merit in a stepwise manner,
• wherein if the measured figure of merit indicates that the actual merit is within the predetermined target range, the non-linearities introduced by the adaptive biasing are evaluated and one or more pre-distortion coefficients used by the pre-distortion element to generate the distorted input signal are updated, and
• wherein if the measured figure of merit indicates that the actual merit is worse than that defined by the predetermined target range, the adaptive biasing element is configured to increase the current consumption and the actual merit.

A method for reducing a current consumption of a transmission circuit, comprising:

• adaptively biasing one or more transmission chain elements to reduce the current consumption of the one or more transmission chain elements, wherein adaptively biasing the one or more transmission chain elements produces non-linearities in an output signal;
• evaluating the non-linearities based upon a feedback signal comprising information about the output signal;
• and
• generating a distorted input signal, input to the one or more transmission chain elements, having distortions to account for non-linearities caused by adaptively biasing the one or more transmission chain elements,
• wherein the measured figure of merit is evaluated against a predetermined target range that defines a range of actual merit,
• wherein if the measured figure of merit indicates that the actual merit is better than that defined by the predetermined target range, the one or more transmission chain elements are adaptively biased to reduce the current consumption in a stepwise manner, thereby reducing the measured figure of merit,
• wherein if the measured figure of merit indicates that the actual merit is within the predetermined target range, the non-linearities introduced by the adaptive biasing are evaluated and one or more pre-distortion coefficients used by to generate the distorted input signal are updated, and
• wherein if the measured figure of merit indicates that the actual merit is worse than that defined by the predetermined target range, the one or more transmission chain elements are adaptively biased to increase the current consumption, thereby increasing the actual merit;
• and
• wherein a value of the measured figure of merit is used to update the adaptive biasing of the one or more digital pre-distortion coefficients based upon one or more mathematical relationships, the mathematical relationships including parameters derived from one or more additional sensors configured to measure external variables including those used to assist determining the measured figure of merit.

A method for reducing a current consumption of one or more transmission chain elements, comprising:

• setting initial bias conditions of one or more transmission chain elements high enough to guarantee good linearity for an output signal and one or more initial pre-distortion coefficients so as to not distort an input signal,
• determining a measured figure of merit of the output signal;
• and
• alternatively or concurrently performing adaptive biasing and updating the pre-distortion coefficients in a stepwise iterative process based on the measured figure of merit,
• wherein the measured figure of merit is evaluated against a predetermined target range that defines a range of actual merit,
• wherein if the measured figure of merit indicates that the actual merit is better than that defined by the predetermined target range, adaptive biasing is performed to reduce the current consumption and the actual merit in a stepwise manner,
• wherein if the measured figure of merit indicates that the actual merit is within the predetermined target range, non-linearities introduced by adjusting the bias conditions are evaluated and one or more pre-distortion coefficients are updated, and
• wherein if the measured figure of merit indicates that the actual merit is worse than that defined by the predetermined target range, adaptive biasing is performed to increase the current consumption and actual merit.