Envelope power supply calibration of a multi-mode radio frequency power amplifier
View Patent ↗The present disclosure relates to envelope power supply calibration of a multi-mode RF power amplifier (PA) to ensure adequate headroom when operating using one of multiple communications modes. The communications modes may include multiple modulation modes, a half-duplex mode, a full-duplex mode, or any combination thereof. As such, each communications mode may have specific peak-to-average power and linearity requirements for the multi-mode RF PA. As a result, each communications mode may have corresponding envelope power supply headroom requirements. The calibration may include determining a saturation operating constraint based on calibration data obtained during saturated operation of the multi-mode RF PA. During operation of the multi-mode RF PA, the envelope power supply may be restricted to provide a minimum allowable magnitude based on an RF signal level of the multi-mode RF PA, the communications mode, and the saturation operating constraint to provide adequate headroom.
1. A method comprising:
obtaining calibration data corresponding with a saturated operating characteristic of a calibration radio frequency (RF) power amplifier (PA), such that the saturated operating characteristic relates magnitudes of an envelope power supply signal, which provides power for amplification to the calibration RF PA, to magnitudes of RF output power from the calibration RF PA during saturated operation of the calibration RF PA;
applying an offset to the saturated operating characteristic to obtain a linear operating characteristic of the calibration RF PA, such that the linear operating characteristic relates magnitudes of the envelope power supply signal to magnitudes of the RF output power during linear operation of the calibration RF PA; and
determining a modulation back-off for each of a plurality of modulation modes of the calibration RF PA, such that each modulation back-off is based on differences between the linear operating characteristic and an operating characteristic of the calibration RF PA that provides a desired output response from the calibration RF PA.
2. The method of claim 1 wherein the desired output response from the calibration RF PA provides a desired output frequency spectrum response from the calibration RF PA.
3. The method of claim 1 wherein the desired output response from the calibration RF PA provides a desired linearity response from the calibration RF PA.
4. The method of claim 1 wherein the desired output response from the calibration RF PA provides a desired error vector magnitude (EVM) response from the calibration RF PA.