Apparatus and method for efficiently amplifying wideband envelope signals

An amplifier circuit for amplifying a RF input signal, comprising:

• an RF amplifier having an input and an output, the input configured to receive the RF input signal;
• a DC-to-baseband switching converter having an input and an output;
• a first feedback loop coupled between the output of the amplifier and the input of the converter;
• and
• a resistive load coupled in parallel between the respective outputs of the amplifier and converter.

An amplifier circuit for amplifying an input signal, comprising:

• a voltage source that operates at a first bandwidth and a first power efficiency, the voltage source configured for generating a first signal having a voltage that varies with the input signal;
• a current source that operates at a second bandwidth no greater than the first bandwidth, and a second power efficiency greater than the first power efficiency, the current source configured for generating a second signal having a current that varies with a current in the first signal;
• and
• a load coupled in parallel between the voltage source and the current source, such that the load is supplied by both the first and second signals.

A system for generating an output signal having both phase modulation and amplitude modulation components, the system comprising:

• a phase-modulated signal amplifier to generate the output signal by amplifying a phase-modulated input signal, the phase-modulated signal amplifier configured for saturated mode operation such that an amplitude of the output signal varies with a supply signal powering the phase-modulated signal amplifier;
• and
• an amplitude-modulated signal amplifier to vary the supply signal responsive to an amplitude-modulated input signal, wherein the amplitude-modulated signal amplifier comprises:
• a first amplifier generating a first signal by amplifying the power residing in one or more lower and higher frequency components of the amplitude-modulated input signal;
• a second amplifier generating a second signal by amplifying the power in one or more lower frequency components of the first signal, such that current in the first signal corresponding to the lower frequency components varies inversely with current in the second signal;
• and
• an output providing the supply signal to the phase-modulated signal amplifier by combining the first and second signals.

A method of amplifying an input signal having one or more lower and higher frequency components, the method comprising:

• amplifying the input signal at a first efficiency to generate a first signal;
• amplifying lower frequency components of the first signal at a second efficiency greater than the first efficiency to generate a second signal;
• and
• varying the lower frequency components of the first signal inversely proportional to the second signal, such that power amplification of the lower frequency components of the input signal is biased toward amplification at the second efficiency.

A method of amplifying a wideband, high frequency input signal exhibiting one or more lower frequency components and one or more higher frequency components comprising:

• generating a first signal by amplifying the power residing in said one or more higher frequency components of the input signal;
• sensing a current of the first signal;
• generating a control signal responsive to the sensed current, wherein the control signal includes said one or more lower frequency components of the input signal;
• generating a second signal by amplifying the power residing in said one or more lower frequency components of the input signal responsive to the control signal;
• and
• combining the first and second signals to produce an amplified input signal.

An amplifier circuit for amplifying a wideband, high frequency input signal having one or more lower frequency components and one or more higher frequency components comprising:

• an input to receive the input signal;
• a first amplifier generating a first signal by amplifying the power residing in said one or more higher frequency components of the input signal;
• a second amplifier generating a second signal by amplifying the power residing in said one or more lower frequency components of the input signal responsive to a control signal;
• a first feedback loop coupled between an output of the first amplifier and an input of the second amplifier, wherein the first feedback loop generates the control signal in response to a current in the first signal and further wherein control signal includes said one or more lower frequency components of the input signal;
• and
• an output providing an output signal as a combination of the first and second signals.