Joint optimisation of supply and bias modulation

1 . A method of controlling at least one amplification stage, comprising:

a. selecting a linearity objective for the amplification stage;

b. in dependence on an input signal to said amplification stage, determining a combination of supply input and bias input for the amplification stage in order to meet said linearity objective; and

c. in dependence on there being more than one combination of supply input and bias input for meeting the linearity objective, selecting the combination that optimises a further system performance objective for the amplification stage.

2 . A method according to claim 1 , wherein the further system performance objective is one or more of: an efficiency objective; an envelope signal bandwidth objective; or a robustness to production tolerance objective.

3 . A method according to claim 1 wherein the supply input and the bias input vary in dependence on a variation in the envelope of the input signal or the power of the input signal and the step of determining a preferred combination is based on an instantaneous value of the input signal.

4 . A method according to claim 1 further comprising the steps of:

a. measuring at least one amplifier dependent characteristic in dependence on at least one amplifier independent characteristic; and

b. determining a preferred combination of bias and supply inputs to achieve the specific system performance objective based on said measurements.

5 . A method according to claim 4 further comprising the steps of:

a. creating a searchable database of said amplifier dependent and independent characteristics;

b. searching said measurement database to simultaneously determine the optimum combination of bias and supply voltage at each input power over the measurement range to achieve specific system performance objectives;

c. wherein step of applying the supply voltage and the bias voltage is based on said determined combinations.

6 . A method according to claim 4 further comprising the steps of:

a. measuring a plurality of amplifier dependent characteristics in dependence on a plurality of amplifier independent characteristics;

b. creating a model of the amplifier operating for emulation of said measured amplifier characteristics;

c. determining from said model the optimum combination of bias and supply voltage at each input power over the measurement range to achieve specific system performance objectives;

d. wherein step of applying the supply voltage and the bias voltage is based on said determined combinations.

7 . A method according to claim 6 wherein said model is in real-time or non-real-time.

8 . A method according to claim 4 wherein the plurality of amplifier independent characteristics are from the group comprising bias voltage; supply voltage; input power; input phase; temperature; device periphery; and load impedance.

9 . A method according to claim 4 wherein the plurality of amplifier dependent characteristics are from the group comprising: output power; output phase; gain; supply current; adjacent channel power; error vector magnitude; correlation coefficient.

10 . A method according to claim 6 wherein the inputs to the model are from the group comprising bias voltage; supply voltage; input power; input phase; temperature; device periphery; and load impedance.

11 . A method according to claim 6 wherein the outputs from the model are from the group comprising: output power; output phase; gain; supply current; adjacent channel power; error vector magnitude; correlation coefficient.

12 . A method according to claim 4 wherein said system performance objectives comprise highest power added efficiency; highest drain efficiency; constant gain; constant phase; lowest adjacent channel power; lowest error vector magnitude; highest correlation coefficient.

13 . A method according to claim 1 wherein the supply and bias inputs are selected in dependence upon one or more previous input signal values.

14 . An amplification stage for amplifying an input signal, the amplification stage having a supply voltage input and bias voltage input, comprising:

a. detection means for detecting the input signal to the amplifier;

b. voltage selection means for selecting a supply input and bias input set for the amplification stage in dependence on the detected input signal, wherein the selected supply and bias inputs are selected to meet a linearity objective for the amplification stage; and further wherein in dependence on there being more than one supply input and bias input set for meeting the linearity objective, selecting the set that optimises a further system performance objective for the amplification stage.

15 . The amplification stage of claim 14 wherein the further system performance objective is one or more of: an efficiency objective; an envelope signal bandwidth objective; or a robustness to production tolerance objective.

16 . An amplification stage according to claim 14 wherein the voltage selection means comprises:

a. a non-linear mapping element for receiving the detected input signal and generating the supply input; and

b. a non-linear mapping means for receiving the detected input signal and generating the bias input.

17 . An amplification stage according to claim 16 wherein each of the respective non-linear mapping means is adapted to approximate an idealised mapping for the detected input signal to meet the specific system performance objective.

18 . An amplification stage according to claim 16 wherein each of said respective non-linear mapping means is a digital linear mapping means.

19 . An amplification stage according to claim 16 wherein each of said respective non-linear mapping means is a digital linear mapping means.

20 . An amplification stage according to claim 14 wherein the non-linear mapping means are configured in accordance with measured results for the amplification stage performance.