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US 6,785,521 B2Granted
System and method for current-mode amplitude modulation
AssigneeEricsson Inc.
InventorsAristotele Hadjichristos, David R. Pehlke
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Abstract
An amplifier circuit includes a power amplifier biased for saturated mode operation, and a controllable current source to provide supply current to the power amplifier. The controllable current source effects desired amplitude modulation of the output signal from the power amplifier by modulating the supply current it provides responsive to an amplitude information signal.
Claims59
A power amplifier circuit comprising:
- a power amplifier biased for saturated mode operation to generate an RF output signal by amplifying a constant-envelope RF input signal;
- and
- a current source responsive to an amplitude information signal to modulate a supply current of said power amplifier to impart desired amplitude modulation to said RF output signal.
A RF transmitter comprising:
- a baseband processor to generate a phase information signal and an amplitude information signal;
- a modulator responsive to said phase information signal to generate a phase-modulated signal with a constant envelope;
- a power amplifier circuit responsive to said phase-modulated signal to generate said RF output signal, said power amplifier circuit comprising:
- a power amplifier biased for saturated mode operation to generate said RF output signal by amplifying said phase-modulated signal;
- and
- a current source responsive to said amplitude information signal to modulate a supply current of said power amplifier to impart desired amplitude modulation to said RF output signal.
3 more elements
A method of modulating a transmit signal, the method comprising:
- amplifying a constant-envelope signal with a power amplifier operating in a saturated mode to generate a transmit signal, said power amplifier having a supply current provided by a variable current source;
- and
- varying said supply current provided by said current source to said power amplifier in response to an amplitude information signal to modulate the amplitude of said transmit signal.
A method of generating a RF transmit signal with both phase and amplitude modulation, the method comprising:
- generating baseband phase and amplitude information signals;
- modulating a RF carrier signal with said phase information signal to generate a constant-envelope phase-modulated signal;
- amplifying said constant-envelope phase-modulated signal with a power amplifier biased for saturated mode operation to generate a RF transmit signal with phase modulation corresponding to said phase information signal;
- and
- modulating a supply current of said power amplifier based on said amplitude information signal to impart amplitude modulation to said RF transmit signal corresponding to said amplitude information signal.
2 more elements
Dependencies are inferred from the claim text.