Abstract: There is described a method of generating a power supply tracking a reference signal, comprising the steps of: filtering the reference signal; generating a first voltage in dependence on the filtered reference signal; generating a second voltage in dependence on the reference signal; and combining the first and second voltages to provide a power supply voltage.

Abstract: A radio frequency amplification stage comprising: an amplifier for receiving an input signal to be amplified and a power supply voltage; and a power supply voltage stage for supplying said power supply voltage, comprising: means for providing a reference signal representing the envelope of the input signal; means for selecting one of a plurality of supply voltage levels in dependence on the reference signal; and means for generating an adjusted selected power supply voltage, comprising an ac amplifier for amplifying a difference between the reference signal and one of the selected supply voltage level or the adjusted selected supply voltage level, and a summer for summing the amplified difference with the selected supply voltage to thereby generate the adjusted supply voltage.

Abstract: There is disclosed an amplifier arrangement comprising a plurality of amplifiers each arranged to amplify one of a plurality of different input signals, the arrangement comprising an envelope tracking modulator for generating a common power supply voltage for the power amplifiers, and further comprising an envelope selector adapted to receive a plurality of signals representing the envelopes of the plurality of input signals, and adapted to generate an output envelope signal representing the one of the plurality of envelopes having the highest level at a particular time instant as the input signal for the envelope tracking modulator.

Abstract: A switched mode power supply arranged to provide a switched supply at one terminal of an inductor, another terminal of the inductor being connected to a first input of an error amplifier having a reference signal at a second input, the error amplifier generating a corrected switched supply at an output in dependence on the difference between signals at its first and second inputs, there being provided a feedback path between the output of the error amplifier and the first input of the error amplifier, and further comprising circuitry for sensing a switcher interference current in the feedback path of the error amplifier, and for adjusting the corrected switched supply output to reduce the switcher interference current in the output.

Abstract: There is provided an amplifier arrangement comprising: a main amplifier connected to receive an input signal and generate an amplified version of the input signal; an additional amplifier, having a smaller geometry than the main amplifier, connected to receive the input signal and generate an amplified version thereof; and wherein the outputs of the main amplifier and the additional amplifier are combined to provide an amplified output.

Abstract: There is described a buck-boost converter comprising: a voltage source; an inductor, wherein a first terminal of the inductor is switchably connected to the voltage source; and a plurality of capacitors switchably connected to a second terminal of the inductor, wherein a respective plurality of output voltages are formed across the plurality of capacitors, further comprising: an error determination means, for determining an error in each of the plurality of voltages, an inner control loop adapted to switchably connect one of the plurality of capacitors to the second terminal of the inductor in dependence on the determined errors; and an outer control loop adapted to control switching between buck mode and boost mode in dependence upon the determined errors.

Abstract: There is disclosed a technique for controlling at least one amplification stage, comprising: selecting a linearity objective for the amplification stage; 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 in dependence on there being more than one combination of supply input and bias input for meeting the linearity objective, selecting the combination that optimizes a further system performance objective for the amplification stage. The further system performance objective may be one or more of: an efficiency objective; an envelope signal bandwidth objective; or a robustness to production tolerance objective.

Abstract: There is disclosed an asynchronous switch mode power supply comprising: a subtractor for subtracting an output of the switch mode power supply from a reference signal; a filter for filtering the subtracted output; a quantiser for generating a plurality of quantiser outputs in dependence on the integrated subtracted output; and a power switch stage for connecting one of a plurality of supply voltages to the output of the switch mode power supply in dependence on the quantiser outputs.

Abstract: A method of controlling an envelope tracking amplification stage comprising: in a characterization mode: measuring parameters of the amplification stage to determine at least two of gain, phase and efficiency characteristics for instantaneous values of input power and supply voltage of the amplifier; and for the at least two of gain, phase and efficiency characteristics, generating a three-dimensional plot representing the characteristic with respect to input power and supply voltage applied to the amplifier, and in a use mode: using at least one of the three-dimensional plots to determine a shaping function for the shaping table in dependence on a primary system objective associated with one or more of gain, phase or efficiency; and using the determined shaping function and at least one of the three dimensional plots to determine the pre-distortion coefficients for the pre-distortion block to meet a secondary system objective associated with at least one of gain, phase or efficiency.

Abstract: There is provided an integrated circuit comprising a main push-pull amplifier (108, 110) with balanced outputs and an additional push-pull amplifier (862, 863) with balanced outputs. Each of these balanced outputs is connected to an off-chip load (822) via respective bonding wires (818, 828, 830, 880) to provide a combined amplified signal to the load. The additional amplifier serves to compensate for crossover distortions generated by the main amplifier.

Abstract: The invention relates to a method of calibrating an envelope path and an input path of an amplification stage including an envelope tracking power supply, the method comprising: generating input signals having a known relationship for each of the input and envelope paths; and varying an amplitude and a delay of the signal in one of the envelope and input paths in order to reduce the variation in the power detected in a signal at the output of the amplification stage.

Abstract: An amplification stage comprising: an input scaling block for scaling an input signal based on an input scaling factor to generate a scaled version of the input signal; a power amplifier for receiving the scaled version of the input signal and for generating an amplified version of said signal; an envelope detector for generating a signal representing the envelope of the input signal; an envelope scaling block for scaling the envelope signal based on an envelope scaling factor to generate a scaled version of the envelope signal; a non-linear mapping block for generating a voltage representative of the supply voltage based on the scaled envelope signal; a modulator for generating a power supply voltage for the amplifier based on the voltage generated by the non-linear mapping block; and a power control block for maintaining a linear relationship between the envelope scaling factor and the input scaling factor.

Abstract: There is disclosed a supply feed network for an envelope tracking power amplifier arrangement comprising a power amplifier and a voltage modulator for providing a supply voltage to the power amplifier, the supply feed network comprising: a power distribution plane arranged to connect the supply voltage from the voltage modulator to the power amplifier.

Abstract: The invention relates to a method of calibrating an envelope path and an input path of an amplification stage of an envelope tracking power supply, the method comprising matching the envelope path to at least one characteristic of at least one element of the input path.

Abstract: There is provided an output stage comprising: a phase splitter for receiving an input signal and for generating first and second drive signals of opposite phase in dependence thereon; a DC offset signal generator for generating a DC offset signal; an adder for adding the DC offset signal to the first drive signal to provide a first modified drive signal; a subtractor for subtracting the DC offset signal from the second drive signal to provide a second modified drive signal; a first drive transistor associated with a first power supply voltage, for generating a first output signal in dependence on the first modified drive signal; a second drive transistor associated with a second power supply voltage, for generating a second output signal in dependence on the second modified drive signal; and a combiner for combining the first and second output signals to generate a phase combined output signal.

Abstract: There is provided a bias arrangement for an amplifier adapted to amplify a varying input signal, the arrangement comprising a control circuit arranged to adaptively vary a bias current to the amplifier in dependence on an envelope of the varying input signal.

Abstract: There is disclosed an arrangement comprising: a driver stage connected to receive an input signal and generate a drive signal; a transformer comprising: a first winding of a first side of the transformer, across which winding a voltage signal is developed in dependence on the drive signal; and a second winding of the first side of the transformer, coupled to the first winding, which exhibits across it a voltage signal related to the voltage across the first winding, by swingback; and a first controller for comparing the voltage exhibited in the second winding to a first threshold voltage, and for selecting a first or a second supply voltage for the arrangement in dependence on the comparison.

Abstract: There is provided a filter for receiving a rectangular or stepped source voltage to be filtered and for providing an output voltage, the filter including means arranged to determine the output voltage in dependence on the frequency components of the source voltage within the filter passband, and independent of output current drawn.

Abstract: An amplification stage comprising: a combiner to generate a sum input signal by combining a voltage signal with a DC bias voltage; a subtractor to generate a difference input signal by subtracting the voltage signal from the DC bias voltage; a first transistor for generating a first part of an amplifier output signal from the sum input signal; a second transistor for generating a second part of an amplifier output signal from the difference input signal; a combiner for combining the first and second parts of the amplifier output signal; a sensing circuit arranged to sense a current flowing in each of the first and second transistors; a control circuit arranged to determine the quiescent current of the first and second transistors in dependence on the sensed currents; and an adjustment circuit arranged to adjust the DC bias voltage in order to minimize variation in the quiescent current.

Abstract: There is disclosed a method, in an amplifier stage comprising an amplifier and a modulated supply, the amplifier being arranged to amplify an input signal and the modulated supply being arranged to generate a supply voltage for the amplifier by tracking an envelope of the signal to be amplified, the method comprising: comparing the relative timing of a signal representing the current drawn by the amplifier from the modulated supply and a signal representing the voltage generated at the output of the modulated supply; and in dependence upon a difference in the relative timing, adjusting the timing of either the input signal to be amplified or the generated supply voltage to reduce the difference in the relative timing.