Current saving by reduced modulation code and selective gating of RF signal
AssigneeST-Ericsson SA
InventorsNorbert Van Den Bos, Roeland Heijna, Hendrik Visser
Life of this patent
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Abstract
A polar modulation power amplifier employs both thermometer coded and binary coded amplitude modulation data. The thermometer coded amplitude modulation data selectively activates one or more equally weighted power amplifier cells. The binary coded amplitude modulation data selectively activates one or more binary weighted power amplifier cells. When less than full output power is required and the MSBs of the amplitude modulation data are zero (reducing output power at the expense of quantization noise), the power dissipated by RF signal buffers for the unused power amplifier cells corresponding to the MSBs is substantially reduced by gating off the RF signal upstream of the buffers.
Claims13
A method of reducing power consumption in a wireless communication transmitter power amplifier, comprising:
- providing a phase-modulated radio frequency periodic signal to a plurality of power amplifier cells;
- receiving digital amplitude modulation data;
- thermometer coding a first plurality of the modulation data bits;
- selectively activating one or more equally weighted power amplifier cells based on the thermometer coded modulation data bits;
- binary coding a second plurality of the modulation data bits;
- selectively activating one or more binary weighted power amplifier cells based on the binary coded modulation data bits;
- receiving an output power requirement indication;
- if the output power requirement exceeds a predetermined threshold, enabling the phase-modulated radio frequency periodic signal to all of the power amplifier cells;
- and
- if the output power requirement is less than the threshold, selectively gating the phase-modulated radio frequency periodic signal upstream of one or more final buffers associated with inactive power amplifier cells, to eliminate switching current in the buffers.
A power amplifier output stage for a wireless communication transmitter, comprising:
- control circuits operative to receive digital amplitude modulation data and an output power requirement indication, and generate digital power amplifier cell enable data;
- a plurality of gating signal drivers operative to receive a phase-modulated radio frequency periodic signal, and to generate a plurality of gated phase-modulated radio frequency periodic signals, each gating signal drivers including
- a final buffer;
- and
- a logic gate upstream of the final buffer, the logic gate receiving the phase-modulated radio frequency periodic signal and one bit of the digital power amplifier cell enable data;
- an encoder operative to thermometer code a first plurality of the modulation data bits and to binary code a second plurality of the modulation data bits;
- a plurality of evenly weighted power amplifier cells each adapted to receive a corresponding one of the plurality of gated phase-modulated radio frequency periodic signal and a thermometer coded modulation data bit, and operative to selectively amplify the gated phase-modulated radio frequency periodic signal if activated by the thermometer coded modulation data bit;
- and
- a plurality of binary weighted power amplifier cells each adapted to receive a corresponding one of the plurality of gated phase-modulated radio frequency periodic signal and a binary coded modulation data bit, and operative to selectively amplify the gated phase-modulated radio frequency periodic signal if activated by the binary coded modulation data bit;
- wherein the control circuits are further operative to selectively gate the phase-modulated radio frequency periodic signal upstream of the final buffer via the digital power amplifier cell enable data if the output power requirement is less than a threshold, to eliminate switching current in the final buffer.
Dependencies are inferred from the claim text.