Integrated transceiver with envelope tracking
A transceiver comprises an amplifying circuit for amplifying an input signal to produce an output signal. A power supply is operable for varying the level of power supplied to the amplifying circuit in response to variation of an input signal envelope directed to the power supply. A processing circuit is operable for digitally detecting the input signal envelope to provide variation of the power supply level. The processing circuit is further operable for digitally delaying the digital input signal envelope to time align the power supply level with the input signal.
1. A transceiver comprising:
an amplifying circuit for amplifying an input signal to produce an output signal;
an envelope-tracking power supply operable for varying the level of power that is supplied to the amplifying circuit in response to variation of an input signal envelope directed to the power supply, the envelope-tracking power supply having non-linearities in the transfer function of the power supply;
a digital signal processing circuit operable for digitally detecting the input signal envelope used by the envelope-tracking power supply to provide the variation of the power supply level to the amplifying circuit;
the digital signal processing circuit including an envelope predistortion circuit operable for receiving the input signal envelope and predistorting the input signal envelope to address non-linearities in the transfer function of the power supply before the input signal envelope is directed to the power supply;
the digital signal processing circuit having a main signal path coupled to the amplifying circuit, an envelope tracking path coupled to the envelope-tracking power supply and an input signal path and feedback signal path each coupled to a portion of the envelope predistortion circuit;
the digital signal processing circuit operable for introducing a digital delay into a signal in at least one of the main signal path, envelope tracking path, input signal path and feedback signal path.
2. The transceiver of claim 1 wherein the digital signal processing circuit is further operable for digitally delaying the signal in the envelope tracking path to time align the power supply level with the input signal.
3. The transceiver of claim 1 wherein the envelope predistortion circuit is adaptable, the digital signal processing circuit further including circuitry for adapting the envelope predistortion circuit based on a signal in at least one of the input signal path and the feedback signal path.
4. The transceiver of claim 1 wherein the digital signal processing circuit includes a main predistortion circuit for digitally predistorting the input signal in the main signal path, the main predistortion circuit including an input signal path and a feedback signal path, the digital signal processing circuit operable for digitally delaying a signal in at least one of the input and feedback signal paths of the main predistortion circuit.
5. The transceiver of claim 4 wherein the main predistortion circuit is adaptable, the digital signal processing circuit including circuitry for adapting the main predistortion circuit based on a signal in at least one of the input signal path and the feedback signal path.
6. A method of amplifying a signal comprising:
amplifying an input signal in a main signal path with an amplifier to produce an output signal;
digitally detecting an envelope of the input signal and varying the level of power that is supplied to the amplifier by an envelope-tracking power supply in response to variation of the input signal envelope, the envelope-tracking power supply having non-linearities in the transfer function of the power supply;
predistorting the input signal envelope in an envelope tracking path with an envelope predistortion circuit to address non-linearities in the transfer function of the power supply before the input signal envelope is directed to the power supply;
introducing a digital delay into a signal in at least one of the main signal path, the envelope tracking path, or an input signal path or feedback signal path coupled to a portion of the envelope predistortion circuit.
7. The method of claim 6 further comprising digitally delaying the signal in the envelope tracking path to time align the power supply level with the input signal.
8. The method of claim 6 further comprising adapting the envelope predistortion circuit with adapting circuitry based on a signal in at least one of the input signal path and the feedback signal path.
9. The method of claim 6 further comprising predistorting the input signal with a main predistortion circuit, the main predistortion circuit including an input signal path and a feedback signal path and digitally delaying a signal in at least one of the input and feedback signal paths of the main predistortion circuit.
10. The method of claim 9 further comprising adapting the main predistortion circuit with adapting circuitry based on a signal in at least one of the input signal path and the feedback signal path.