Abstract: There is described an amplification stage comprising: a current mirror circuit comprising a reference transistor arranged to receive a current associated with an input signal and an output transistor providing a current source for an output signal line; a current sink to the output signal line, under the control of the input signal; circuitry arranged to maintain equality between the drain/collector voltages on the transistors of the current mirror circuit.

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 a method and apparatus for generating an output signal comprising a replica of an input signal, comprising the steps of: generating a replica signal representing the low frequency content of the input signal; generating an error signal representing an error in the replica signal; combining the replica signal with the error signal to generate an output signal; and wherein the step of generating the error signal further includes the steps of: generating a delay signal being a delayed version of the input signal; and determining a difference between the output signal and the delay signal which difference is the error signal.

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: 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 described a method of controlling signal alignment in a power amplifier, comprising: receiving an input signal to be amplified; receiving a supply voltage for the power amplifier, the supply voltage being derived in dependence on the signal to be amplified; amplifying the input signal to produce an output signal; comparing the output signal with a plurality of distorted versions of the input signal, each distorted version of the input signal being associated with a different time delay value; and adjusting the timing of either the input signal or the supply voltage by an amount in dependence on a time delay value determined to be associated with a distorted version of the input signal which most closely matches the output signal.

Abstract: There is disclosed a power supply stage, comprising: generating means for generating a power supply voltage from a high efficiency variable voltage supply in dependence on a reference signal; adjusting means for receiving the generated power supply voltage, and adapted to provide an adjusted selected power supply voltage tracking the reference signal in dependence thereon.

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.

Abstract: A method of calibrating a polar amplification stage including a main signal path and a magnitude signal path, the method comprising: generating signals (108, 142) for the main signal path and the magnitude signal path for operating an amplifier (102) between a linear mode of operation and a saturated mode of operation; detecting (114) first and second peaks in a signal at the output of the amplifier (102) representing transitions between the linear and saturated modes of operation; and adjusting (124) the timing in one of the main signal path and the amplitude signal path in dependence on a relative difference between the size of the detected first and second peaks.

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: 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: 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 described a method of controlling signal alignment in a power amplifier, comprising: receiving an input signal to be amplified; receiving a supply voltage for the power amplifier, the supply voltage being derived in dependence on the signal to be amplified; amplifying the input signal to produce an output signal; comparing the output signal with a plurality of distorted versions of the input signal, each distorted version of the input signal being associated with a different time delay value; and adjusting the timing of either the input signal or the supply voltage by an amount in dependence on a time delay value determined to be associated with a distorted version of the input signal which most closely matches the output signal.

Abstract: There is disclosed a voltage supply stage comprising: a selection means for selecting one of a plurality of power supply voltages in dependance 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.

Abstract: There is disclosed a power supply stage, comprising: generating means for generating a power supply voltage from a high efficiency variable voltage supply in dependence on a reference signal; adjusting means for receiving the generated power supply voltage, and adapted to provide an adjusted selected power supply voltage tracking the reference signal in dependence thereon.

Abstract: A power amplifier circuit comprising a transistor for receiving a signal to be amplified at an input and for outputting an amplified signal at an output; a modulated power supply connected to the transistor output; and a resistive element connected at the transistor output such that a low impedance is maintained at the transistor output across a range of operational frequencies.

Abstract: In accordance with the invention there is also provided a voltage combiner comprising: a transformer having a first and second winding each having a first and second tap; and an inductor connected between the first and second taps of the second winding, wherein: the first tap of the first winding is adapted for connection to a first voltage, the first tap of the second winding is adapted for connection to a second voltage, and the second tap of the second winding is adapted to provide an output being the first and second voltages combined, and further wherein: the inductor is adapted to provide a bypass path for the current associated with the second voltage.

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 method for generating pre-emphasis coefficients for a pre-emphasis stage of a non-linear distorting device, the method comprising the steps of: capturing, for a given time period, samples of an input signal and samples of an output signal; determining the direction of an error between the captured samples; adjusting the input signal in a direction to reduce the error to generate an estimate of the pre-distorted input signal; generating updated pre-distortion coefficients in dependence on the estimate of the pre-distorted input signal and generated pre-distortion coefficients for one or more previous time periods.