Group delay calibration method for power amplifier envelope tracking
First Claim
1. An open loop envelope tracking system comprising:
- a digital baseband circuit configured to;
generate a modulated signal based on a calibration test signal;
generate a control signal based on the calibration test signal and a fine tuning delay setting of a fine tuning delay circuit;
an envelope tracker power converter configured to generate a modulated power amplifier supply voltage based on the control signal;
a radio frequency power amplifier configured to generate a radio frequency power amplifier output signal based on the modulated signal and the modulated power amplifier supply voltage; and
a detector configured to generate an output power measurement for the radio frequency power amplifier output signal;
controller circuitry configured to;
set the fine tuning delay setting to a first fine tuning delay setting;
obtain a first measured output power from the radio frequency power amplifier output signal based on the output power measurement generated by the detector while the fine tuning delay setting is set to the first fine tuning delay setting;
set the fine tuning delay setting to a second fine tuning delay setting;
obtain a second measured output power from the radio frequency power amplifier output signal based on the output power measurement generated by the detector while the fine tuning delay setting is set to the second fine tuning delay setting; and
determine a calibrated fine tuning offset delay setting based on the first fine tuning delay setting and the second fine tuning delay setting.
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Abstract
An open loop envelope tracking system calibration technique and circuitry are proposed. A radio frequency power amplifier receives a modulated signal. An envelope tracker power converter generates a modulated power amplifier supply voltage for the radio frequency power amplifier based on a control signal derived from the modulated signal. A first output power and a second output power of the radio frequency power amplifier are measured when the control signal is respectively delayed by a first delay period and a second delay period. A sensitivity of the output power of the radio frequency power amplifier is near a maximum near the first delay period and the second delay period. The first delay period and/or the second delay period are adjusted until the first output power substantially equals the second output power. The first delay period and the second delay period are used to obtain a calibrated fine tuning delay offset.
288 Citations
42 Claims
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1. An open loop envelope tracking system comprising:
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a digital baseband circuit configured to; generate a modulated signal based on a calibration test signal; generate a control signal based on the calibration test signal and a fine tuning delay setting of a fine tuning delay circuit; an envelope tracker power converter configured to generate a modulated power amplifier supply voltage based on the control signal; a radio frequency power amplifier configured to generate a radio frequency power amplifier output signal based on the modulated signal and the modulated power amplifier supply voltage; and a detector configured to generate an output power measurement for the radio frequency power amplifier output signal; controller circuitry configured to; set the fine tuning delay setting to a first fine tuning delay setting; obtain a first measured output power from the radio frequency power amplifier output signal based on the output power measurement generated by the detector while the fine tuning delay setting is set to the first fine tuning delay setting; set the fine tuning delay setting to a second fine tuning delay setting; obtain a second measured output power from the radio frequency power amplifier output signal based on the output power measurement generated by the detector while the fine tuning delay setting is set to the second fine tuning delay setting; and determine a calibrated fine tuning offset delay setting based on the first fine tuning delay setting and the second fine tuning delay setting. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for calibrating a group delay for an open loop envelope tracking system comprising:
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generating a radio frequency power amplifier output signal having a first output power at an output of a radio frequency power amplifier based on a modulated signal as a function of a control signal delayed in time by a first delay relative to the modulated signal; generating the radio frequency power amplifier output signal having a second output power at the output of the radio frequency power amplifier as the function of the control signal delayed in time by a second delay relative to the modulated signal; determining a calibrated offset delay as a function of the second delay and the first delay; calculating a power difference between the first output power and the second output power; and determining that the first output power substantially equals the second output power based on the power difference. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A method for calibrating a group delay for the open loop envelope tracking system comprising:
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obtaining an initial value for a negative fine tuning delay and an initial value for a positive fine tuning delay; receiving a substantially symmetric modulated signal with a radio frequency power amplifier; until a determination that a negative fine tuning delay output power is substantially equal to a positive fine tuning delay output power, iteratively performing sub-steps of; generating a modulated power amplifier supply control signal related to the substantially symmetric modulated signal based on the positive fine tuning delay; generating a modulated power amplifier supply voltage related to the substantially symmetric modulated signal based on the modulated power amplifier supply control signal advanced in time by the negative fine tuning delay; measuring the negative fine tuning delay output power of the radio frequency power amplifier; generating the modulated power amplifier supply control signal related to the substantially symmetric modulated signal based on the positive fine tuning delay; generating the modulated power amplifier supply voltage related to the substantially symmetric modulated signal based on the modulated power amplifier supply control signal delayed in time by the positive fine tuning delay; measuring the positive fine tuning delay output power of the radio frequency power amplifier; determining whether the negative fine tuning delay output power is substantially equal to the positive fine tuning delay output power; and in response to a determination that the negative fine tuning delay output power is not substantially equal to the positive fine tuning delay output power, adjusting the negative fine tuning delay and the positive fine tuning delay based on the negative fine tuning delay output power and the positive fine tuning delay output power; and after the determination that the negative fine tuning delay output power is substantially equal to the positive fine tuning delay output power, determining a calibrated fine tuning delay based on the negative fine tuning delay and the positive fine tuning delay.
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42. A method for calibrating a group delay for an open loop envelope tracking system comprising:
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at a first time, generating a radio frequency power amplifier output signal having a first output power at an output of a radio frequency power amplifier based on a modulated signal as a function of a control signal delayed in time by a first delay relative to the modulated signal; at a different time, generating the radio frequency power amplifier output signal, such that the radio frequency power amplifier output signal has a second output power at the output of the radio frequency power amplifier as a function of the control signal delayed in time by a second delay relative to the modulated signal; and determining a calibrated offset delay as a function of the second delay and the first delay.
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Specification