Modulated supply stage with feedback to switched supply

Abstract

There is disclosed a voltage supply stage comprising: a selection means for selecting one of a plurality of power supply voltages in dependence on a reference signal representing a desired power supply voltage; a combining means for combining the selected power supply voltage with a correction signal to generate an adjusted power supply voltage; and an adjusting means adapted to generate the correction signal in dependence on the reference signal and the adjusted power supply voltage, wherein the selection means is arranged to select the one of the plurality of supply voltages further in dependence on a signal derived from one of the inputs to the combining means.

What is claimed is: 
     
         1 .- 48 . (canceled) 
     
     
         49 . A voltage supply stage comprising: a selection means for selecting one of a plurality of power supply voltages in dependence on a reference signal representing a desired power supply voltage; an inductor for combining the selected power supply voltage with a correction signal to generate an adjusted power supply voltage, wherein a current representing the correction signal is injected at a second terminal of the inductor, a thus adjusted current flowing in a load connected to the second terminal of the inductor to thereby develop the adjusted supply voltage across said load; and a voltage-to-current converter adapted to generate the correction signal in dependence on the reference signal, wherein the selection means is arranged to select the one of the plurality of supply voltages further in dependence on a signal derived from the output of the voltage-to-current converter. 
     
     
         50 . The voltage supply stage according to  claim 49  further comprising a feedback control stage for providing the signal derived from the output of the voltage-to-current converter. 
     
     
         51 . The voltage supply stage according to  claim 50  wherein the feedback control stage is adapted to receive as a first input the reference signal and as a second input the output of the voltage-to-current converter, and further adapted to adjust the reference signal in dependence on the output of the voltage-to-current converter to provide an adjusted reference signal for the selection means. 
     
     
         52 . The voltage supply stage according to  claim 51 , wherein the feedback control stage comprises: a proportional-integral, PI, controller for receiving the output of the adjusting means and generating a modified output, and a summer for adding the modified output of the PI controller to the reference signal, to form the output of the feedback control stage being the adjusted reference signal. 
     
     
         53 . The voltage supply stage according to  claim 49  further comprising a reference adjustment stage for adjusting the reference signal to provide a modified reference signal. 
     
     
         54 . The voltage supply stage according to  claim 53  wherein the selection means is adapted to select in dependence on the modified reference signal. 
     
     
         55 . The voltage supply stage according to  claim 53  wherein the reference adjustment stage adjusts the reference signal in dependence on a signal derived from the output of the voltage-to-current converter. 
     
     
         56 . The voltage supply stage according to  claim 55  further comprising a feedback control stage adapted to receive as a first input the modified reference signal and as a second input the output of the voltage-to-current converter, and further adapted to adjust the modified reference signal in dependence on the output of the voltage-to-current converter to provide an adjusted modified reference signal for the selection means. 
     
     
         57 . The voltage supply stage according to  claim 55  further comprising a feedback control stage adapted to receive as a first input the modified reference signal and as a second input the output of the selection means, and further adapted to adjust the modified reference signal in dependence on the output of the selection means to provide an adjusted modified reference signal for the selection means. 
     
     
         58 . The voltage supply stage according to  claim 53  wherein the reference adjustment stage comprises circuitry for adjusting the amplitude of the reference signal in dependence upon a difference between the amplitude of the reference signal and the amplitude of the output of the voltage-to-current converter. 
     
     
         59 . The voltage supply stage according to  claim 58  wherein the circuitry for adjusting the amplitude of the reference signal includes: a correlator for determining the amplitude error between the reference signal and the amplitude of the output of the voltage-to-current converter; and an amplitude adjustment block for modifying the reference signal in dependence on said error. 
     
     
         60 . The voltage supply stage according to  claim 53  wherein the reference adjustment stage comprises circuitry for controlling a current flow in the inductor to maximize current flow in the inductor and thereby minimize current flow in the voltage-to-current converter. 
     
     
         61 . The voltage supply stage according to  claim 60  wherein the circuitry for controlling the current flow includes: a correlator for determining the current flow in the inductor and for providing a control signal to modify coefficients of a differentiator in dependence thereon, the differentiator being arranged to receive the reference signal and generate a differentiated version thereof. 
     
     
         62 . The voltage supply stage according to  claim 61 , wherein the differentiator is arranged to receive as an input the amplitude adjusted reference signal generate a differentiated amplitude adjusted reference signal, the reference adjustment stage further comprising a summer for summing the amplitude adjusted reference signal with the differentiated amplitude adjusted reference signal to form the modified reference signal. 
     
     
         63 . A tracking modulated power supply stage for a mobile wireless device including the voltage supply stage according to  claim 49 . 
     
     
         64 . A method for generating a supply voltage comprising: selecting one of a plurality of power supply voltages in dependence on a reference signal representing a desired power supply voltage; combining the selected power supply voltage with a correction signal in an inductor to generate an adjusted power supply voltage, injecting a current representing the correction signal at the second terminal of the inductor; generating the correction signal as a current in dependence on the reference signal and the adjusted power supply voltage; and providing as a feedback signal the correction signal, and wherein an adjusted current flowing in a load connected to the second terminal of the inductor to thereby develop the adjusted supply voltage across said load wherein the selecting step is further arranged to select the one of the plurality of supply voltages in dependence on the feedback signal. 
     
     
         65 . The method according to  claim 64  further comprising the step of controlling the feedback signal by receiving as a first input the reference signal and as a second input the correction signal, and adjusting the reference signal in dependence on the correction signal to provide an adjusted reference signal for the selecting step. 
     
     
         66 . The voltage supply stage according to  claim 64  further comprising a reference adjustment stage for adjusting the reference signal to provide a modified reference signal wherein the reference adjustment stage adjusts the reference signal in dependence on a signal derived from the output of the voltage-to-current converter, and further comprising a feedback control stage adapted to receive as a first input the modified reference signal and as a second input the output of the voltage-to-current converter, and further adapted to adjust the modified reference signal in dependence on the output of the voltage-to-current converter to provide an adjusted modified reference signal for the selection means. 
     
     
         67 . The voltage supply stage according to  claim 64  further comprising a reference adjustment stage for adjusting the reference signal to provide a modified reference signal wherein the reference adjustment stage adjusts the reference signal in dependence on a signal derived from the output of the voltage-to-current converter, and further comprising a feedback control stage adapted to receive as a first input the modified reference signal and as a second input the output of the selection means, and further adapted to adjust the modified reference signal in dependence on the output of the selection means to provide an adjusted modified reference signal for the selection means. 
     
     
         68 . The voltage supply stage according to  claim 64  wherein the reference adjustment stage comprises circuitry for controlling a current flow in the inductor to maximize current flow in the inductor and thereby minimize current flow in the voltage-to-current converter.