Switched amplifier
AssigneeAndrew Corporation
InventorPeter Kenington
Life of this patent
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Abstract
An imput signal is provided in polar format comprising an amplitude component (210) and a phase component (212). The amplitude component (210) is supplied to a pulse width modulator (219) which derives pulse width modulated (PWM) signal. The PWM signal is used to control a switch (224) which modulates the phase component (212). The modulated phase component (212) is amplified at (216). The output of amplifier (216) has a desired envelope, as dictated by the PWM signal, whose characteristics are, in turn, derived from the amplitude component (210). Either or both of the amplitude component (210) and the phase component (212) can be predistorted (226, 218).
Claims26
Apparatus for amplifying an input signal to produce an output signal, comprising means for providing the input signal in polar format comprising amplitude and phase components, amplifying means and modulating means, wherein the modulating means modulates the phase component with a pulse width modulated (PWM) signal derived from the amplitude component and the amplifying means receives the modulated phase component for amplification to produce the output signal.
Apparatus according to any preceding claim, further comprising a linearisation scheme for counteracting distortion in the apparatus.
Apparatus according to any preceding claim, wherein the input signal is provided in quadrature format, and the means for providing the input signal in polar format comprises means for converting the quadrature signal into a polar signal.
A method of amplifying an input signal to produce an output signal, comprising providing the input signal in polar form comprising an amplitude component and a phase component, modulating the phase component with a pulse width modulated (PWM) signal derived from the amplitude component and amplifying the modulated phase component to produce the output signal.
Apparatus for amplifying a signal, substantially as hereinbefore described with reference to any one of FIGS. 2 to 9.
A method of amplifying a signal, substantially as hereinbefore described with reference to any one of FIGS. 2 to 9.
Dependencies are inferred from the claim text.