Amplitude modulation to phase modulation cancellation method in an RF amplifier
First Claim
1. An RF amplifier comprising:
- command means developing a phase modulation command representing a desired phase modulation of an RF signal and an amplitude modulation command representing a desired amplitude modulation of the RF signal;
an oscillator developing an RF input signal phase modulated based on the phase modulation command;
a power amplifier receiving the RF input signal and amplifying the RF input signal based on the amplitude modulation command to develop an RF output signal;
a modulation control operatively associated with the oscillator, the modulation control including phase memory means for storing phase correction information correlating the amplitude modulation command to a phase modulation error and phase control means for varying the phase modulation command based on the phase modulation error to correct for unintended phase errors created by amplitude modulation of the power amplifier.
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Abstract
An RF amplifier for a transmitter develops a phase modulation command representing a desired phase modulation of an RF signal, and an amplitude modulation command representing a desired amplitude modulation of the RF signal. An oscillator develops an RF input signal phase modulated based on the phase modulation command. A power amplifier receives the RF input signal and amplifies the RF input signal based on the amplitude modulation command to develop an RF output signal. A modulation control is operatively associated with the oscillator. The modulation control includes a phase memory for storing phase correction information correlating the amplitude modulation commands to a phase modulation error and a phase control for varying the phase modulation command based on the phase modulation error to correct for unintended phase errors created by amplitude modulation of the power amplifier.
139 Citations
26 Claims
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1. An RF amplifier comprising:
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command means developing a phase modulation command representing a desired phase modulation of an RF signal and an amplitude modulation command representing a desired amplitude modulation of the RF signal;
an oscillator developing an RF input signal phase modulated based on the phase modulation command;
a power amplifier receiving the RF input signal and amplifying the RF input signal based on the amplitude modulation command to develop an RF output signal;
a modulation control operatively associated with the oscillator, the modulation control including phase memory means for storing phase correction information correlating the amplitude modulation command to a phase modulation error and phase control means for varying the phase modulation command based on the phase modulation error to correct for unintended phase errors created by amplitude modulation of the power amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. The method of developing an RF signal with both phase and amplitude modulation comprising the steps of:
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developing a phase modulation command representing a desired phase modulation of an RF signal;
developing an amplitude modulation command representing a desired amplitude modulation of the RF signal;
shifting the phase of the RF signal to provide an RF input signal phase modulated based on the phase modulation command;
amplifying the RF input signal based on the amplitude modulation to develop an RF output signal;
storing phase correction information correlating the amplitude modulation command to a phase modulation error; and
varying the phase modulation command based on the phase modulation error to correct for unintended phase errors created by amplitude modulation of the RF input signal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification