RF amplifier with digital filter for polar transmitter
AssigneeST-Ericsson SA
InventorJohannes Petrus Antonius Frambach
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Abstract
An RF power amplifier for a polar transmitter converts an amplitude component signal into a 1-bit digital amplitude signal, which is fed to a digital finite impulse response filter. Successive taps of the filter each have an RF amplification stage arranged to amplify successively delayed versions of the 1-bit digital amplitude signal, the amplifying being according to a respective tap coefficient, and according to the RF carrier modulated by the phase component. The filter is arranged to combine the outputs of the taps to provide the amplified RF signal. The power amplifier uses a one bit stream which therefore has only two states (2 values), thus achieving linearity in principle. Device mismatch between taps does not lead to non-linearity or distortion.
Claims15
An RF power amplifier for providing an amplified RF signal based on an amplitude component signal and an RF carrier modulated by a phase component, the RF power amplifier comprising:
- a converter for converting the amplitude component signal into a 1-bit digital amplitude signal, and
- a digital finite impulse response filter fed by the 1-bit digital amplitude signal,
- wherein successive taps of the filter each includes an RF amplification stage arranged to amplify successively delayed versions of the 1-bit digital amplitude signal, the amplifying being performed according to a respective tap coefficient, and according to the RF carrier modulated by the phase component,
- wherein the filter is arranged to combine outputs of the taps to provide the amplified RF signal.
A method of amplifying an RF signal, having the steps of:
- converting an amplitude component signal into a 1-bit digital amplitude signal,
- feeding this signal to a digital finite impulse response filter so that successive taps of the filter each amplifies successively delayed versions of the 1-bit digital amplitude signal,
- wherein the amplifying is according to a respective tap coefficient, and according to the RF carrier modulated by the phase component, combining outputs of the taps to provide an amplified RF signal.
Dependencies are inferred from the claim text.