System and methods for stimulating and training a power amplifier during non-transmission events
First Claim
1. In a transmitter in which an input transmission signal is separated into multiple component signals which are processed along respective amplification chains and then combined, a method of compensating for differences in the amplification chains, comprising the steps of:
- (a) separating the input transmission signal into multiple component signals having envelopes of varying phase and substantially constant amplitude;
(b) processing the component signals along the respective amplification chains, the step of processing comprising modifying the component signals prior to amplification based on compensation parameters to adaptively compensate for differences in analog components of the amplification chains;
(c) combining the component signals following amplification to produce an output signal;
and, when the transmitter is not transmitting an information signal;
(d) applying training signals to the amplification chains while substantially inhibiting transmissions from the transmitter; and
(e) while applying the training signals in step (d), adaptively updating the compensation parameters.
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Accused Products
Abstract
A LINC amplifier of a radio frequency transmitter provides substantially linear amplification from two nonlinear amplifiers by decomposing the original signal into two constant amplitude envelope, phase varying signals, which, when combined, constructively and destructively interfere to re-form the original signal. The output of the LINC amplifier, which is to be transmitted via an antenna, is an amplified form of the original signal. The LINC amplifier uses a digital control mechanism to control and adapt a digital compensation network that directly compensates for the imperfections of the analog RF environment, including the amplifiers. The mechanism monitors the combined amplifier output and adjusts the signal components in order to precisely compensate for any differences in the characteristics of the separate signal paths which would cause the combination not to accurately represent the original signal. The mechanism also corrects the component signals using information which can be applied to the amplifiers independent of the signal to be transmitted.
196 Citations
40 Claims
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1. In a transmitter in which an input transmission signal is separated into multiple component signals which are processed along respective amplification chains and then combined, a method of compensating for differences in the amplification chains, comprising the steps of:
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(a) separating the input transmission signal into multiple component signals having envelopes of varying phase and substantially constant amplitude; (b) processing the component signals along the respective amplification chains, the step of processing comprising modifying the component signals prior to amplification based on compensation parameters to adaptively compensate for differences in analog components of the amplification chains; (c) combining the component signals following amplification to produce an output signal; and, when the transmitter is not transmitting an information signal; (d) applying training signals to the amplification chains while substantially inhibiting transmissions from the transmitter; and (e) while applying the training signals in step (d), adaptively updating the compensation parameters. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. In radio frequency (RF) transmission system in which an input transmission signal is separated into first and second component signals, and in which the component signals are processed along respective first and second amplification chains and then combined to produce an output signal which is applied to an antenna, a method of reducing an imbalance between the amplification chains during non-transmission events so as to substantially inhibit energy emissions from the antenna, comprising:
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(a) applying a first stimulation signal to the first amplification chain during a non-transmission event; (b) concurrently with step (a), applying a second stimulation signal which is substantially in antiphase with the first stimulation signal to the second amplification chain; (c) monitoring a level of balance between the amplification chains during the application of the stimulation signals to the amplification chains; and (d) based on the step of monitoring, adaptively modifying the operation of a compensation processor of at least one of the amplification chains to reduce the imbalance; wherein the first and second stimulation signals substantially cancel when combined, so that RF emissions from the antenna are substantially inhibited during training without the need for an antenna switch. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A LINC transmitter, comprising:
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a signal component separator which separates an input transmission signal into multiple component signals of substantially constant amplitude and varying phase; a plurality of amplification chains coupled to the signal component separator such that each amplification chain processes a respective component signal, the amplification chains including compensation processors which modify the component signals, based on compensation parameters, to compensate for differences in analog components of the amplification chains; a signal combiner which combines the component signals following processing along the amplification chains; an adaptive compensation estimator which adaptively generates the compensation parameters used by the compensation processors; and a training signal generator which generates signals for training the compensation processors; wherein the signal component separator applies the training signals to the amplification chains during non-transmission events to cause the adaptive compensation estimator to adaptively update the compensation parameters. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. In radio frequency (RF) transmission system in which an input transmission signal is separated into first and second component signals, and in which the component signals are processed along respective first and second amplification chains and then combined to produce an output signal which is applied to an antenna, a method of stimulating the first and second amplification chains during non-transmission events so as to substantially inhibit energy emissions from the antenna, comprising:
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(a) applying a first stimulation signal to the first amplification chain; and (b) concurrently with step (a), applying a second stimulation signal which is substantially in antiphase with the first stimulation signal to the second amplification chain; wherein the first and second stimulation signals substantially cancel when combined, so that RF emissions from the antenna are substantially inhibited during stimulation without the need for an antenna switch, and the steps of applying the stimulation signals to the amplification chains comprise using a frequency hopping sequence to vary the frequencies of the first and second stimulation signals over a range of frequencies, so that a residual energy transmitted from the antenna is spread out over the range of frequencies.
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36. In radio frequency (RF) transmission system in which an input transmission signal is separated into first and second component signals, and in which the component signals are processed along respective first and second amplification chains and then combined to produce an output signal which is applied to an antenna, a method of stimulating the first and second amplification chains during non-transmission events so as to substantially inhibit energy emissions from the antenna, comprising:
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(a) applying a first stimulation signal to the first amplification chain; and (b) concurrently with step (a), applying a second stimulation signal which is substantially in antiphase with the first stimulation signal to the second amplification chain; wherein the first and second stimulation signals substantially cancel when combined, so that RF emissions from the antenna are substantially inhibited during stimulation without the need for an antenna switch, and the steps of applying the first and second stimulation signals to the amplification chains are performed when no input transmission signal is present.
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37. In radio frequency (RF) transmission system in which an input transmission signal is separated into first and second component signals, and in which the component signals are processed along respective first and second amplification chains and then combined to produce an output signal which is applied to an antenna, a method of stimulating the first and second amplification chains during non-transmission events so as to substantially inhibit energy emissions from the antenna, comprising:
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(a) applying a first stimulation signal to the first amplification chain; and (b) concurrently with step (a), applying a second stimulation signal which is substantially in antiphase with the first stimulation signal to the second amplification chain; wherein the first and second stimulation signals substantially cancel when combined, so that RF emissions from the antenna are substantially inhibited during stimulation without the need for an antenna switch, and the steps of applying the stimulation signals to the amplification chains are performed between consecutive time division multiple access (TDMA) transmissions while the transmission system is operating in a TDMA mode.
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38. A transmitter, comprising:
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a signal component separator circuit which separates an input transmission signal into first and second component signals; first and second amplification chains coupled to the signal component separator such that each amplification chain processes a respective one of the component signals; a signal combiner circuit which combines the first and second component signals following processing along the amplification chains; an antenna coupled to the signal combiner circuit; and a signal generator which generates first and second stimulation signals that are substantially in antiphase, and applies the first and second stimulation signals to the first and second amplification chains, respectively, when the transmitter is not transmitting an information signal; wherein the first and second stimulation signals substantially cancel when combined by the signal combiner, so that RF emissions from the antenna are substantially inhibited during application of the stimulation signals. - View Dependent Claims (39, 40)
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Specification