Abstract: There is disclosed a voltage regulator, including a switching stage, for generating an output voltage, the voltage regulator comprising a feedback path for controlling the switching stage, in which a feedback signal in the feedback path is ramp-compensated, the ramp for the ramp compensation being generated from an output of the switching stage.

Abstract: There is disclosed a method of controlling an envelope tracking amplification stage comprising an envelope modulated power supply, the method comprising: determining a shaping function to be applied to an envelope signal for controlling the envelope modulated power supply in dependence on a system linearity objective in a region of operation of the amplifier in which the output power of the amplifier is dependent upon the supply voltage; and determining a pre-distortion function to be applied to an input signal to be amplified in dependence on a further linearity objective of the system, in a region of operation of the amplifier in which the output of the amplifier is dependent upon the input power to the amplifier.

Abstract: There is disclosed an envelope tracking modulated supply arranged to generate a modulated supply voltage in dependence on a reference signal, comprising a low frequency path for tracking low frequency variations in the reference signal and including a switched mode power supply, a correction path for tracking high frequency variations in the reference signal and including a linear amplifier, a feedback path from the output of the linear amplifier to the input of the linear amplifier, and a combiner for combining the output of the switched mode power supply and the output of the linear amplifier to generate a modulated supply voltage.

Abstract: There is disclosed a voltage regulator, including a switching stage, for generating an output voltage, the voltage regulator comprising a feedback path for controlling the switching stage, in which a feedback signal in the feedback path is ramp-compensated, the ramp for the ramp compensation being generated from an output of the switching stage.

Abstract: A method of characterizing an envelope tracking amplification stage, the method comprising: generating an input test waveform which is representative of an input waveform under normal operating conditions of the amplification stage; applying a respective one of a plurality of different shaping functions, each comprising a non-linear transfer function, to the input signal envelope in each of a plurality of test periods during the period in which the input test waveform is applied as the input signal to generate the input to the envelope tracking modulated supply voltage; measuring parameters of the amplification stage during the period in which the input test waveform is applied in order to allow determination of the gain, phase and efficiency characteristics of the amplifier; and for each of the gain, phase and efficiency characteristics, generating a three dimensional plot of the characteristic with respect to input power and supply voltage applied to the amplifier.

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: There is disclosed an envelope tracking modulated supply arranged to generate a modulated supply voltage in dependence on a reference signal, comprising a low frequency path for tracking low frequency variations in the reference signal and including a switched mode power supply, a correction path for tracking high frequency variations in the reference signal and including a linear amplifier, a feedback path from the output of the linear amplifier to the input of the linear amplifier, and a combiner for combining the output of the switched mode power supply and the output of the linear amplifier to generate a modulated supply voltage.

Abstract: There is disclosed an envelope tracking power supply arranged to generate a modulated supply voltage in dependence on a reference signal, comprising a first path for tracking low frequency variations in the reference signal and a second path for tracking high frequency variations in the reference signal, the second path including a linear amplifier, wherein the output of the linear amplifier comprises a current source and a current sink connected to the high frequency output, there further being provided a DC offset current at the high frequency output.

Abstract: There is disclosed an envelope tracking modulated supply arranged to generate a modulated supply voltage in dependence on a reference signal, comprising a low frequency path for tracking low frequency variations in the reference signal and including a switched mode power supply, a correction path for tracking high frequency variations in the reference signal and including a linear amplifier, a feedback path from the output of the linear amplifier to the input of the linear amplifier, and a combiner for combining the output of the switched mode power supply and the output of the linear amplifier to generate a modulated supply voltage.

Abstract: An envelope tracking power supply arranged to generate a modulated supply voltage in dependence on a reference signal, comprising a first path for tracking low frequency variations in the reference signal and a second path for tracking high frequency variations in the reference signal, and further comprising a combiner having a low frequency combining element for the first path and a high frequency combining element for the second path, and for generating the modulated supply voltage, wherein there is further provided sensing circuitry for sensing a resonance signal in the low or high frequency combining element, and adjusting circuitry for adjusting a signal in the first path in dependence on the sensed resonance signal.

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: There is provided an amplification stage including an envelope tracking modulated supply for tracking a reference signal, comprising a low frequency path for tracking low frequency variations in the reference signal and for providing a first output voltage, and a high frequency path for tracking high frequency variations in the reference signal and for providing a second output voltage, and a combiner for combining the first and second output voltages to provide a third output voltage, the amplification stage further comprising a first amplifier arranged to receive the first output voltage as a supply voltage, and a second amplifier arranged to receive the third output voltage as a supply voltage, wherein the first and second amplifiers are enabled in different modes of operation.

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 disclosed a multi-stage amplifier comprising: a first amplifier stage; a second amplifier stage; a first voltage supply stage arranged to provide a supply voltage to the first amplifier in dependence on an average power of a signal to be amplified; and a second voltage supply stage arranged to provide a supply voltage to the second amplifier in dependence on an instantaneous power of a signal to be amplified.

Abstract: There is disclosed a voltage supply stage comprising an input supply voltage, a first (102) and second (104) switch connected in series, the first (102) and second (104) series-connected switches being connected in parallel with the input supply voltage between first and second terminals of the input supply voltage, a third (106) switch and capacitor connected in series, the series-connected third (106) switch and capacitor being connected in parallel with the first (102) switch, a fourth (108) switch connected between the connection of the third switch and the capacitor and an output, and a fifth (110) switch connected between the output and a terminal of the input supply voltage, wherein: in a first phase of operation, the first and the fourth switch are closed, and the second, third and fifth switches are open; in a second phase of operation, the second, third and fifth switches are closed, and the first and fourth switches are open; and the duty cycle of the first and second phases is controlled such that

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: 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: There is provided an amplification stage including an envelope tracking modulated supply for tracking a reference signal, comprising a low frequency path for tracking low frequency variations in the reference signal and for providing a first output voltage, and a high frequency path for tracking high frequency variations in the reference signal and for providing a second output voltage, and a combiner for combining the first and second output voltages to provide a third output voltage, the amplification stage further comprising a first amplifier arranged to receive the first output voltage as a supply voltage, and a second amplifier arranged to receive the third output voltage as a supply voltage, wherein the first and second amplifiers are enabled in different modes of operation.

Abstract: There is disclosed an envelope tracked power supply comprising a high bandwidth, low delay closed loop switch mode power supply stage comprising: a pulse width modulator for generating a width modulated pulse in dependence on an input signal and an output voltage of the switch mode power supply stage; a wideband transformer, having a winding of a first side connected to receive the modulated pulse, and a winding of a second side; and an output stage connected to the winding of the second side of the transformer, and for generating the output voltage in dependence on the modulated pulse induced in the winding of the second side.

Abstract: There is disclosed a power amplifier arrangement comprising: first and second active devices for amplifying in-phase and anti-phase parts of an input signal; a first DC supply network connected between the output of the first active device and a modulated supply voltage; a second DC supply network connected between the output of the second active device and the same modulated supply voltage and an output combiner for combining the amplified in-phase and anti-phase parts of the input signal.