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. Radio frequency (RF) communications circuitry comprising:
RF power amplifier (PA) circuitry associated with a first saturation operating constraint and adapted to:
receive and amplify a first RF input signal to provide a first RF output signal; and
receive an envelope power supply signal, which provides power for amplification; and
control circuitry adapted to:
select one of a plurality of communications modes;
determine a first desired magnitude of the first RF input signal;
determine a minimum allowable magnitude of the envelope power supply signal based on the first saturation operating constraint, the selected one of the plurality of communications modes, and the first desired magnitude; and
restrict a magnitude of the envelope power supply signal based on the minimum allowable magnitude; and
RF modulation circuitry adapted to provide the first RF input signal having approximately the first desired magnitude and having RF modulation corresponding to the selected one of the plurality of communications modes,
wherein the first saturation operating constraint is based on first calibration data obtained during saturated operation of a calibration RF PA at different envelope power supply levels.
2. The RF communications circuitry of claim 1 wherein the first desired magnitude of the first RF input signal is based on a desired magnitude of the first RF output signal, which is based on a desired RF output power from the RF PA circuitry.
3. The RF communications circuitry of claim 1 wherein the first saturation operating constraint is further based on an offset, which is based on differences between a saturated operating characteristic of the calibration RF PA and a linear operating characteristic of the calibration RF PA.
4. The RF communications circuitry of claim 3 wherein the first saturation operating constraint is further based on a modulation back-off for the selected one of the plurality of communications modes, such that the modulation back-off is based on differences between the linear operating characteristic of the calibration RF PA and a modulation specific operating characteristic of the calibration RF PA associated with the selected one of the plurality of communications modes.
5. The RF communications circuitry of claim 1 wherein the RF PA circuitry comprises a first RF PA having the first saturation operating constraint and adapted to:
receive and amplify the first RF input signal to provide the first RF output signal; and
receive the envelope power supply signal, which provides power for amplification to the first RF PA, such that the calibration RF PA is the first RF PA.
6. The RF communications circuitry of claim 1 wherein:
the RF PA circuitry comprises a first RF PA and a second RF PA;
the first RF PA has the first saturation operating constraint and is adapted to:
receive and amplify the first RF input signal to provide the first RF output signal; and
receive the envelope power supply signal, which provides power for amplification to the first RF PA;
the second RF PA has a second saturation operating constraint and is adapted to:
receive and amplify a second RF input signal to provide a second RF output signal; and
receive the envelope power supply signal, which provides power for amplification to the second RF PA;
the control circuitry is further adapted to:
select one of the first RF PA and the second RF PA;
when the first RF PA is selected, determine the first desired magnitude of the first RF input signal;
when the second RF PA is selected, determine a second desired magnitude of the second RF input signal;
when the first RF PA is selected, determine the minimum allowable magnitude of the envelope power supply signal based on the first saturation operating constraint, the selected one of the plurality of communications modes, and the first desired magnitude; and
when the second RF PA is selected, determine the minimum allowable magnitude of the envelope power supply signal based on the second saturation operating constraint, the selected one of the plurality of communications modes, and the second desired magnitude; and
the RF modulation circuitry is further adapted to:
when the first RF PA is selected, provide the first RF input signal having approximately the first desired magnitude and having RF modulation corresponding to the selected one of the plurality of communications modes; and
when the second RF PA is selected, provide the second RF input signal having approximately the second desired magnitude and having RF modulation corresponding to the selected one of the plurality of communications modes.
7. The RF communications circuitry of claim 6 wherein the second saturation operating constraint is about equal to the first saturation operating constraint.
8. The RF communications circuitry of claim 6 wherein the calibration RF PA is the first RF PA and the second saturation operating constraint is based on second calibration data obtained during saturated operation of the second RF PA at different envelope power supply levels.
9. The RF communications circuitry of claim 6 wherein the first RF PA is a highband RF PA and the second RF PA is a lowband RF PA.