Patents Assigned to Nujira Limited
  • Publication number: 20120019320
    Abstract: There is disclosed a method for determining the timing misalignment between a power supply and an output in an envelope tracking amplification stage, the method including the steps of: estimating a distortion parameter in the amplification stage; and determining a timing error in dependence on the estimated distortion parameter.
    Type: Application
    Filed: March 30, 2011
    Publication date: January 26, 2012
    Applicant: NUJIRA LIMITED
    Inventor: Shaun Cummins
  • Patent number: 8093945
    Abstract: A radio frequency amplifier system is disclosed in which the amplifier bias supply and power supply voltages are instantaneously modulated with signals derived from the envelope voltage of the input signal. Separate non-linear mapping functions are used to derive the supply and bias voltages. The two mapping functions are optimised jointly to achieve particular system performance goals, such as optimum efficiency, constant gain, constant phase, or minimum spectral spreading. An optimisation of particular interest is that which achieves best RF amplifier power added efficiency subject to achieving constant amplifier gain. In this way the need for pre-distortion linearization may be reduced or eliminated.
    Type: Grant
    Filed: March 19, 2007
    Date of Patent: January 10, 2012
    Assignee: Nujira Limited
    Inventor: Gerard Wimpenny
  • Patent number: 8093946
    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.
    Type: Grant
    Filed: September 11, 2009
    Date of Patent: January 10, 2012
    Assignee: Nujira Limited
    Inventors: Gerard Wimpenny, Julian Hildersley, Robert Henshaw, Yi Qin
  • Patent number: 8093979
    Abstract: There is disclosed a voltage summer including a transformer having a primary side and a secondary side, wherein a first voltage to be summed is connected to the primary side and a second voltage to be summed is connected to the secondary side. There is further disclosed a transformer comprising a primary winding and a secondary winding and having a turns ratio of primary winding to secondary winding of x:y, providing x turns in series in the primary winding and providing y turns in series in the secondary winding; providing an equal number of turns in the primary and secondary windings; and closely coupling each primary winding turn with a secondary winding turn.
    Type: Grant
    Filed: June 11, 2010
    Date of Patent: January 10, 2012
    Assignee: Nujira Limited
    Inventor: Martin Paul Wilson
  • Publication number: 20110234182
    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.
    Type: Application
    Filed: May 8, 2009
    Publication date: September 29, 2011
    Applicant: NUJIRA LIMITED
    Inventor: Martin Paul Wilson
  • Publication number: 20110109391
    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.
    Type: Application
    Filed: January 6, 2011
    Publication date: May 12, 2011
    Applicant: NUJIRA LIMITED
    Inventor: Martin Paul Wilson
  • Publication number: 20110095837
    Abstract: There is disclosed a method and apparatus for generating, in an envelope tracking modulator of a mobile radio transmission apparatus, a pulse width modulated, PWM, signal representing a time-varying signal, the method comprising, for each time cycle: a) generating a rising ramp from a first voltage level to a second voltage level; b) generating a falling ramp from the second voltage level to the first voltage level; c) detecting a rising slope of the time-varying signal crossing the falling ramp and responsive thereto if the PWM signal is at the first voltage level, transitioning the PWM signal to the second voltage signal; d) detecting a falling slope of the time-varying signal crossing the rising ramp, and responsive thereto if the PWM signal is at the second voltage level, transitioning the PWM signal to the first voltage signal.
    Type: Application
    Filed: April 20, 2009
    Publication date: April 28, 2011
    Applicant: NUJIRA LIMITED
    Inventor: Martin Paul Wilson
  • Publication number: 20110095846
    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.
    Type: Application
    Filed: February 27, 2009
    Publication date: April 28, 2011
    Applicant: NUJIRA LIMITED
    Inventor: Gerard Wimpenny
  • Publication number: 20110089990
    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.
    Type: Application
    Filed: February 27, 2009
    Publication date: April 21, 2011
    Applicant: NUJIRA LIMITED
    Inventor: Gerard Wimpenny
  • Publication number: 20110090007
    Abstract: There is disclosed a power supply stage, and a corresponding method, comprising: a plurality of amplifiers for amplifying an input signal, each amplifier receiving a power supply voltage; a common selection means for selecting one of a plurality of power supply voltages in dependence on a reference signal representing a desired power supply voltage; and a plurality of adjusting means, corresponding to the plurality of amplifiers, adapted to generate an adjusted selected power supply voltage for a respective amplifier tracking the reference signal in dependence on the one selected power supply voltage and the reference signal.
    Type: Application
    Filed: April 9, 2009
    Publication date: April 21, 2011
    Applicant: NUJIRA LIMITED
    Inventor: Gerard Wimpenny
  • Publication number: 20110084680
    Abstract: In accordance with the invention there is also provided a voltage combiner (200) comprising: a transformer (104) having a first (108) and second (110) winding each having a first and second tap; and an inductor (120) 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 (114), the first tap of the second winding is adapted for connection to a second voltage (102), 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 (120) is adapted to provide a bypass path for the current associated with the second voltage.
    Type: Application
    Filed: February 27, 2009
    Publication date: April 14, 2011
    Applicant: NUJIRA LIMITED
    Inventor: Gerard Wimpenny
  • Patent number: 7868698
    Abstract: A Stabilizing circuit (530) is connected to the output of a power amplifier transistor (502) in order to prevent the amplifier from being oscillating. The stabilizing circuit (530) comprises basically a resistor (536) connected in series with a capacitor (534). The stabilizing circuit may also comprise an inductor (532) connected in series to the capacitor and the resistor. The inductor may be partially or fully realised by printed conductive lines and/or bonding wires. The stabilizing circuit provides a low impedance at the transistor output across a range of operational frequencies.
    Type: Grant
    Filed: February 9, 2005
    Date of Patent: January 11, 2011
    Assignee: Nujira Limited
    Inventor: Martin Paul Wilson
  • Publication number: 20100253460
    Abstract: There is disclosed a voltage summer including a transformer having a primary side and a secondary side, wherein a first voltage to be summed is connected to the primary side and a second voltage to be summed is connected to the secondary side. There is further disclosed a transformer comprising a primary winding and a secondary winding and having a turns ratio of primary winding to secondary winding of x:y, providing x turns in series in the primary winding and providing y turns in series in the secondary winding; providing an equal number of turns in the primary and secondary windings; and closely coupling each primary winding turn with a secondary winding turn.
    Type: Application
    Filed: June 11, 2010
    Publication date: October 7, 2010
    Applicant: NUJIRA LIMITED
    Inventor: Martin Paul Wilson
  • Patent number: 7764060
    Abstract: There is disclosed a voltage summer including a transformer having a primary side and a secondary side, wherein a first voltage to be summed is connected to the primary side and a second voltage to be summed is connected to the secondary side. There is further disclosed a transformer comprising a primary winding and a secondary winding and having a turns ratio of primary winding to secondary winding of x:y, providing x turns in series in the primary winding and providing y turns in series in the secondary winding; providing an equal number of turns in the primary and secondary windings; and closely coupling each primary winding turn with a secondary winding turn.
    Type: Grant
    Filed: December 7, 2004
    Date of Patent: July 27, 2010
    Assignee: Nujira Limited
    Inventor: Martin Paul Wilson
  • Publication number: 20100073088
    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 optimises 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.
    Type: Application
    Filed: September 11, 2009
    Publication date: March 25, 2010
    Applicant: Nujira Limited
    Inventors: Gerard Wimpenny, Julian Hildersley, Robert Henshaw, Yi Qin
  • Publication number: 20090302941
    Abstract: A radio frequency amplifier system is disclosed in which the amplifier bias supply and power supply voltages are >instantaneously modulated with signals derived from the envelope voltage of the input signal. Separate non-linear mapping functions are used to derive the supply and bias voltages. The two mapping functions are optimised jointly to achieve particular system performance goals, such as optimum efficiency, constant gain, constant phase, or minimum spectral spreading. An optimisation of >particular interest is that which achieves best RF amplifier power added efficiency subject to achieving constant amplifier gain. In this way the need for pre-distortion linearization may be reduced or eliminated.
    Type: Application
    Filed: March 19, 2007
    Publication date: December 10, 2009
    Applicant: NUJIRA LIMITED
    Inventor: Gerard Wimpenny
  • Patent number: 7482869
    Abstract: A radio frequency amplification stage including 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, including a circuit for providing a reference signal representing the envelope of the input signal; a circuit for selecting one of a plurality of supply voltage levels in dependence on the reference signal; and a circuit for generating an adjusted selected power supply voltage, including 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.
    Type: Grant
    Filed: August 19, 2005
    Date of Patent: January 27, 2009
    Assignee: Nujira Limited
    Inventor: Martin Paul Wilson