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US 6,438,360 B1Granted
Amplifier system with load control to produce an amplitude envelope
AssigneeMotorola, Inc.
InventorsWilliam P. Alberth, Jr., Armin Klomsdorf, Luke Winkelmann
Life of this patent
Estimating the term…
Abstract
An amplifier system to increase the efficiency of amplification systems that employ linear modulation schemes. The amplifier system has a signal amplifier for receiving a constant amplitude input signal and producing an amplified version of the input signal. A variable impedance network presents various impedances to an output of the signal amplifier responsive to a load control signal. An envelope mapping circuit coupled to the variable impedance network produces the load control signal responsive to a desired amplitude modulation (AM) envelope. The various impedances causes the desired AM envelope to be impressed upon the amplified version of the input signal.
Claims20
An amplifier system comprising:
- a signal amplifier having an input and an output, the input for receiving a substantially constant envelope input signal;
- a variable impedance network coupled to the output of the signal amplifier, the variable impedance network for presenting various impedances to the output of the signal amplifier responsive to a load control signal to impress upon the substantially constant envelope input signal a desired amplitude modulation (AM) envelope to produce an output signal having an AM envelope;
- and
- an envelope mapping circuit coupled to the variable impedance network, the envelope mapping circuit for producing the load control signal responsive to the desired AM envelope.
1 more element
A transmitter for transmitting a modulated information signal, the transmitter comprising:
- a control circuit for converting user input information into a data stream and for producing a signal representative of a desired amplitude modulation (AM) envelope;
- transmitter circuitry coupled to the control circuit for processing the data stream to form a constant envelope phase modulated (PM) signal;
- and
- an amplifier system coupled to the transmitter circuitry, the amplifier system including,
- a power amplifier coupled to receive the constant envelope PM signal,
- a variable impedance network coupled to receive a load control signal and coupled to an output of the power amplifier, the load control signal causing the variable impedance network to present various impedances to the output of the power amplifier, and
- an envelope mapping circuit coupled to the variable impedance network and the control circuit, the envelope mapping circuit to produce the load control signal responsive to the signal representative of the desired AM envelope,
- wherein the various impedances cause the desired AM envelope to be impressed upon the constant envelope PM signal at an output of the variable impedance network.
5 more elements
A method of transmitting user input information comprising:
- converting the user input information into a data stream;
- producing a substantially constant amplitude signal;
- amplifying the substantially constant amplitude signal with a power amplifier;
- and
- varying a load impedance presented to an output of the power amplifier according to a desired amplitude modulation (AM) envelope to amplitude modulate the output of the power amplifier.
2 more elements
A method of transmitting user input information comprising:
- converting the user input information into a data stream;
- phase modulating a carrier signal with the data stream to form a constant envelope phase modulated (PM) signal;
- generating a load control signal responsive to the data stream;
- amplifying the constant envelope PM signal with a power amplifier;
- and
- presenting various impedances to an output of the power amplifier responsive to the load control signal to impress upon the constant envelope PM signal amplitude modulation representative of the data stream and a chosen modulation scheme.
3 more elements
A method of transmitting user input information comprising:
- converting the user input information into an input signal;
- modulating a carrier wave signal with the input signal to form a modulated signal having an amplitude modulation (AM) envelope;
- removing at least a portion of the AM envelope to form a processed signal;
- amplifying the processed signal with a power amplifier;
- and
- varying a load impedance at an output of the power amplifier to restore the at least a portion of the AM envelope.
3 more elements
A radiotelephone comprising:
- a user interface for receiving input information and presenting transmitted data;
- a control circuit for controlling the radiotelephone, the control circuit for converting the input information into an input signal;
- a receiver coupled to the control circuit and the user interface, the receiver for receiving the transmitted data and directing the transmitted data to the user interface;
- a synthesizer for generating a radio frequency (RF) carrier signal;
- and
- a transmitter coupled to the control circuit, the user interface, and the synthesizer, the transmitter coupled to receive the input signal and the RF carrier signal, the transmitter for modulating the RF carrier signal with the input signal to form a modulated input signal having an amplitude modulation (AM) envelope, the transmitter having a load envelope elimination and restoration power amplifier (LEER PA) system including,
- an amplitude limiting element coupled to receive the modulated input signal to remove at least a portion of the AM envelope from the modulated input signal to form a limited signal,
- a power amplifier coupled to receive the limited signal to produce an amplified signal at an output of the power amplifier,
- a variable impedance network coupled to receive the amplified signal and a load control signal, the load control signal causing the variable impedance network to present various impedances to the output of the power amplifier responsive to amplitude variations of the modulated input signal having the AM envelope, and
- an envelope mapping circuit coupled to the variable impedance network and the control circuit, the envelope mapping circuit for producing the load control signal indicative of the amplitude variations of the modulated input signal having the AM envelope.
7 more elements
A transmitter for transmitting a modulated information signal, the transmitter comprising:
- a control circuit for converting user input information into an input signal and for providing an indication of a desired average transmit power;
- transmitter circuitry coupled to the control circuit for processing the input signal to form a substantially constant envelope signal;
- and
- an amplifier system coupled to the transmitter circuitry, the amplifier system including,
- a power amplifier coupled to receive the substantially constant envelope signal to produce an amplified signal at an output of the power amplifier,
- a variable impedance network coupled to receive the amplified signal and a load control signal, the load control signal causing the variable impedance network to present various impedances to the output of the power amplifier,
- an envelope mapping circuit coupled to the variable impedance network, the control circuit, and the transmitter circuitry, the envelope mapping circuit to produce the load control signal responsive to the indication of the desired average transmit power and the user input information, the envelope mapping circuit to produce a supply voltage control signal related to the indication of the desired average transmit power, and
- a voltage control circuit for receiving the supply voltage control signal, producing a supply voltage responsive to the supply voltage control signal, and applying the supply voltage to the power amplifier.
5 more elements
A transmitter for transmitting a modulated information signal, the transmitter comprising:
- a control circuit for converting user input information into an input signal and for providing an indication of a desired average transmit power;
- transmitter circuitry coupled to the control circuit for processing the input signal to form a substantially constant envelope signal;
- and
- an amplifier system coupled to the transmitter circuitry, the amplifier system including,
- a power amplifier coupled to receive the substantially constant envelope signal to produce an amplified signal at an output of the power amplifier,
- a variable impedance network coupled to receive the amplified signal and a load control signal, the load control signal causing the variable impedance network to present various impedances to the output of the power amplifier, and
- an envelope mapping circuit coupled to the variable impedance network, the control circuit, and the transmitter circuitry, the envelope mapping circuit to produce the load control signal responsive to the indication of the desired average transmit power and the user input information, the envelope mapping circuit to produce a bias control voltage proportional to the indication of the desired average transmit power,
- wherein the bias control voltage is applied to the power amplifier to cause a bias current of the power amplifier to vary in response to the indication of the desired average transmit power.
5 more elements
A transmitter for transmitting a modulated information signal, the transmitter comprising:
- a control circuit for converting user input information into a data stream;
- transmitter circuitry coupled to the control circuit for processing the data stream to produce a signal representative of a desired amplitude modulation (AM) envelope and to produce a constant envelope input signal;
- and
- an amplifier system coupled to the transmitter circuitry, the amplifier system including,
- a power amplifier coupled to receive the constant envelope input signal,
- a variable impedance network coupled to receive a load control signal and coupled to an output of the power amplifier, the load control signal causing the variable impedance network to present various impedances to the output of the power amplifier, and
- an envelope mapping circuit coupled to the variable impedance network and the control circuit, the envelope mapping circuit to produce the load control signal responsive to the signal representative of the desired AM envelope,
- wherein the various impedances cause the desired AM envelope to be impressed upon the constant envelope input signal at an output of the variable impedance network.
5 more elements
Dependencies are inferred from the claim text.